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Air Hoods Air Hood substitutes The air hoods on a fuel-injected TR7 are very prone to cracking as they age. When they crack, they admit air that has not been metered by the fuel-injection electronics, thus causing the engine to run too lean. This increases the operating temperature, and in my car, lead to premature valve burning. The hoods should be replaced as soon as cracking is visible. On original cars, I would recommend replacing them as a preventative maintenance exercise. These air hoods are the curved hoses between the air plenum and the cylinders. They can be inspected merely by raising the hood. These parts have not been available from TRF or VB for longer than five years. They are available through other British parts suppliers. I paid $45 for one once and $35 another time, but I recommend the repair I am about to describe as superior and less expensive. Bill Sohl invented this fix. I reported on brands 1 and 2 below, and Sharon Oblinger contributed the data on #3. The repair is to buy 90 degree rubber elbows for 1.5" plumbing. You will cut these until they are about 45 degree of arc in length, and install them with hose clamps. Here is the rundown on some brands: #1 #2 #3 Manuf: Fernco, Inc. unknown Mission Davidson, MI 48423 unknown Whittier, CA Model: PlumbQwik 1.5" unknown #M90L-150 Qwik-ell PQL-150 Cut to: Smaller than Longer than Longer than half length half length half length Mods: Remove additional None, very unknown material from the good fit inside diameter at the middle of the elbow using a utility knife Cost: $6.99 x 2 = $13.98 $9.79 x 4 $8 x 4 Items marked #2 and #3 above are probably the same item. Joe Gorin |
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Air Pump Air pumps and stuff 28 August 1994 Regarding the mention of emissions stuff required to pass the new visual inspection, J.C. Witney lists an air pump for 78-81 TR8 3.5L models and the price is (hold on to your hats) $49.95!!!!. That is right and there are not any missing 000's. Anyone know if this piece is an OE replacement or just something that "will work". Mark Elbers |
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Auto Chokes Carburettor Chokes 6 March 1995 Both autostarters were seized full on. The metering needles were stuck in the bores. Liberal amounts of carb cleaner and gentle persuasion with a pin punch got them moving, and a good soaking freed them up the rest of the way. These have been cited as common trouble spots. What is the usual failure mode for these things? Do the manual choke kits replace these with the low-tech (but effective) autostart valve used on earlier carbs? If I put a finger over the port on the back of the autostarter, the vacuum kick piston would take under a second to travel its full length. Is this about right? There was no visible wear, but it seems to me that this would cause a steady leak of vacuum during normal operation, since the inside of the autostarter is ported to the air. The manual says not to lubricate this, but a drop of oil might help to seal it too. Both carbs were badly gunked up. And this was after liberal use of carb cleaners in the gas. I guess the way the vapour recovery lines are hooked up, only one float needle would have to have been stuck to fill up both carbs. One would overflow the float chamber, and fill the other via the vapour line. The floats moved very stiffly in their hinges due to the sludge, and one needle valve was indeed stuck full open. So this, along with the stuck-open chokes, helps to explain why I was running a bit rich. Some other observations: The two carbs aren't the same. One says '175 CD 2' and the other '175 CD'. The only visible difference is the throttle linkages. (Does the '2' mean a carb for a twin-carb setup with double-ended throttle linkage?) The TRF rebuild kits came with Grose Jets. When I got a kit for my Spit a few years ago, they didn't. Both carbs still held oil in the dashpot, so I saw no need to touch the metering needles (unlike my Spitfire, where I removed the needle and thus messed up the mixture). Can I assume that this won't be out of adjustment? I was careful to file off the screw-exit ridges from the throttle shafts before removing them, (I think David Huddleson warned me about this) I didn't have new throttle-plate screws as mandated by the manual, so I put the old ones back on with a drop of non-permanent loctite (the blue kind). Do I need to worry about eating a throttle plate and having a runaway engine some day?? Scott Miller |
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Carburettors Carb Tuning 12 May 1995 I have my manifold off the car, so I took a close look at it last night tosee which carb feeds which cylinder. Here's what I found: My manifold has ERC 0242 cast into it near the #1 cylinder. It also has ERC 5483 stamped into it underneath where the EGR inlet fitting bolts on between the two carbs. It is a two-plane manifold, where the left carb flows into the top plane, and the right carb flows into the bottom plane. The top plane (left carb) flows into cylinders 1, 4, 6, and 8. The bottom plane (right carb) flows into cylinders 2, 3, 5, 8. There is a small balancing port underneath the EGR inlet, between the two carbs. With a firing order of: 1 8 4 3 6 5 7 2, you end up with flow: from these planes: T B T B T B T B from these carbs: L R L R L R L R This data should help you to set the mixture with a Colortune. I've used a Colortune with my TR6 since it's obvious which carb goes where, but haven't used it on the TR8 since I didn't know which carb fed which cylinder. Tim Buja Rockford, IL Idle Speed 8 January 1996 The change in idle speed may be caused by a sticky bypass valve. Each Stromberg carburettor has one on the front side next to the throttle shaft. The valves open to let a little intake bypass the throttles during engine conditions such as "engine braking" when you down shift and let the engine slow you down. Also, they are sometimes called "gulp valves" due to the fact that they open and close whenever you rev the engine and let off the throttle. I think that what happens is that one or both of your bypass valves are sticking when the engine compartment heats up. The valve has a diaphragm and spring inside that seat against the carb body. Vacuum behind the diaphragm normally is not high enough to overcome the spring tension, so the bypass channel remains closed. If there is dirt there, it could keep the valve from closing all the way. If the diaphragm is broken, it could cause a vacuum leak but that is very rare. To remove the bypass valve, remove the three slot head screws. DO NOT REMOVE the COUNTERSUNK PHILLIPS head screws, as they hold the two halves of the valve together, and you dont want to lose or damage any of the parts inside! Just remove the unit and press on the brass valve face with the eraser head of a pencil to see if it has free meovement against the spring pressure. If it moves freely, try it again only this time plug the vacuum fitting when it is compressed. The diaphragm should hold it open. If it fails either of these tests, you probably need a new diaphragm. I have seen them advertised by Moss. (800-667-7872) Clean the face of the carb (where the valve face seats) with laquer thinners. There is a gasket between the bypass valve and the carb body that you will need to replace. If this is not the problem, I will be surprised. Three years ago, I had a 1980 TR7 Spyder with carbs that had this exact problem. RDG |
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Coolant Temp EFI Coolant Temperature Sensor 9 March 1995 John Horton (the one with the FI TR8 which bucks under constant throttle) called me up tonight with good news. His coolant temp sensor was OPEN (read: bad). He substituted an appropriate resistor and the car ran. He also disconnected the throttle pot and said the car is MUCH smoother than before. No bucking at all. He has ordered a new coolant temp sensor and will see about cleaning up the throttle pot (or replacing it) later. Neato! Jim |
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ECU Surging Problem Solved 21 February 1995 Believe it or not it has taken me this long to track down my surging problem. As per your advice I carefully removed the ECU and resoldered all the connections on the outside of the ECU board opposite the power transistors. Unfortunately it didn't solve my problem. Just to be sure my problem was in fact electronic and not mechanical I blocked the cold start injector to see if it was leaking, tested the extra air valve as per the repair manual, and removed the fuel pressure regulator hose to test for leaks. Everything checked out and my problem persisted. The only items not checked were the O2 sensors. One had been replaced about a year ago but the other was original. I substituted in a new sensor for the other relatively new one to be sure I hadn't previously installed a defective unit. No change. I then replaced the old unit with a new one and still no improvement. Boy was I getting frustrated! The happy ending comes in my doing what I should have done in the first place, really listening to the engine idle for a long period of time. When I did I noticed that the surging would mysteriously and unpredictably stop and then resume a few seconds later. The periods of normal idle were few and far between but clearly indicated a bad connection somewhere. I resumed my search by cleaning all connections and contacts starting at the O2 sensors and working my way back to the ECU. Still no change. The problem was obviously still in the ECU. I removed it a second time and resoldered all connections on the backs of both circuit boards. STILL no improvement. Finally, I took the ECU apart a third time (I'm getting good at this) and noticed that inside the unit, opposite the soldered side of the board, there are a number of parts (mostly resistors) that are soldered to posts that are in turn themselves soldered to the board. I resoldered these components to the posts and resoldered all the wires that connect the two boards together. Once again back in the car and unbelievable, it worked! I believe the bad solder connections were the ones inside the board where components connect to the posts. The moral of the story is that for those who may have this problem, firstly listen to your engine idle for 15 minutes or so to see if it is constant or intermittent. Secondly, if you are going to resolder connections in the ECU be sure to get BOTH sides of BOTH boards or you may miss the problem. L.R.Gridley Optimizing FI Tuning/Reducing Emissions 6 June 1995 Here are the interesting results of some experimentation from last weekend, with comments from Jim TenCate. You can quite possibly improve the performance and the emissions from FI wedges by adjusting the two interactive adjustments of the fuel-air mixture. Now that the wedges about 15 years old, the adjustments have probably drifted. Benefits/Theory/Implementation: Benefits Improved tuning will reduce the emissions from the car when it is cold and at idle. In clean FI cars, this is a major portion of the total pollution created by the car. Improved tuning should also improve performance in the "transient" condition, in other words, as your engine speed changes. I have not personally found this to be a noticable improvement, though. [Jim's comments below probably refute this benefit, and add another.] Lastly, good tuning can reduce the idle wandering problem that causes us concern about the condition of our cars. Benefits/Theory/Implementation: Theory The FI system on TR7s and TR8s are Bosch L-Jetronic systems with O2 feedback. This means that the amount of fuel to be injected is computed by analog electronics based on many sensors (air temperature, block (water) temperature, throttle switch, and most importantly airflow) and the computation result is modified by feedback from the oxygen sensor (also called the O2 sensor or lambda sensor) to keep the mixture at an ideal level. When the lambda sensor is cold, such as when the car is cold or when the car has been idling for a few minutes, the lambda sensor does not function, and so the electronics works "open loop"; there is no feedback of how accurately the air-fuel mixture has been set. When the feedback is present, it is not ultra-fast, so that the open-loop performance is also important when going through the gears. By adjusting the two adjustments on the airflow meter, you adjust the open-loop performance of the fuel injection system to optimize the mixture without the feedback from the oxygen sensor. The airflow meter measures the airflow by measuring the angle of a flap in the air stream; as the combustion rate increases, more air travels past this flap and pushes it against the spring that tries to close it down. The flap is connected to a potentiometer (this is a variable resistor, like a volume control) that is precisely designed for the car and has a logarithmic relationship between airflow and voltage output. This logarithmic relationship allows the same good percentage sensitivity for low volumes of air as for high volumes of air. Unfortunately, the precision of this system depends on the spring return force, which may change with age. The airflow meter also has a bypass path around the measuring flap with a screw adjustment for the air resistance of this path. The screw, which is easily accessible, is called the "idle air/fuel mix adjustment" or similar. The bypass has a larger percentage effect at idle than it does with larger air currents of course, so it should be adjusted at idle. Because the electronics is designed to function open loop when the oxygen sensor is cold, and because when it is cold it acts as though it is disconnected, you can disconnect the sensor to evaluate the open loop performance. And you can read the sensor output to tell whether the operation is too lean or too rich. 0.45 V is the output of the sensor at the ideal mixture. It changes very rapidly with mixture from about 0.1V to about 1 V. Benefits/Theory/Implementation: Implementation I developed this technique on a TR7; TR8s will be similar in concept but not in details. There are two adjustments: the tension of the spring on the airflow flap and the idle mixture bypass path adjustment. To gain access to the spring, remove the black plastic cover on the airflow meter. On the TR7, you cannot do this without removing the airflow meter/air filter assembly from the car, then removing the air filter assembly from the airflow meter, then putting the meter back in the car. You can measure the fuel/air ratio with a voltmeter connected to the oxygen sensor output. Disconnect the oxygen sensor from the control electronics at the connector about five inches up the cable from the oxygen sensor. Connect the oxygen sensor output to the positive terminal of an analog voltmeter (these give you a better feel for rapidly varying signals like we'll see here) and connect the voltmeter negative terminal to ground. The voltmeter needs to be a not-poor model. Analog voltmeters are rated in terms of how much current they require to deflect the meter. Most good voltmeters are 20,000 ohms per volt, and will work well enough on the 10 V range. I don't think 5000 ohm/V or lower rated voltmeters will work acceptably. The positive terminal will need to connect to a female quick disconnect 0.250 inch terminal, and you will need to be able to keep it connected "hands free." The negative terminal should be connected to ground, for example the battery minus terminal. I made a cable to connect the voltmeter, so that I could read it from a position next to the airflow meter. Increase the idle speed adjustment to about 2000 rpm, and let the car heat up for a few minutes to get the O2 sensor hot. Then adjust the spring tension by rotating the toothed collar around the spring. You should probably have marked the original position of the spring with a dot of paint before starting. I found that I had to adjust my 15 year old spring to be tighter by 5 teeth at this stage. You need to adjust the spring tension so that the meter reads above 0.45 V about as often as it reads below 0.45 V. You cannot get this reading to be perfect, but a one-tooth change in position is pretty dramatic on the meter. Reduce the idle to 800 rpm +/-100 rpm and adjust the idle mix adjustment for the same meter reading. The exhaust gasses are not always hot enough if you idle for a few minutes, so try to make this adjustment rapidly. I found that I had to turn my idle adjust clockwise by 1.2 turns. Then repeat the measure/adjust cycle at 2000 rpm, then again at idle. I found that I had to readjust the spring tension back to four teeth above original after readjusting the idle screw, and the next adjustment of the idle screw resulted in a small change there, too. Put the car back together, including reconnecting the O2 sensor, and go try it out. It should work great. I used to have a little hesitation/choking when I backed out of a parking place, and it's gone now. And I know I am polluting less on those short trips. Comments from Jim TenCate (1) On the TR8, I also found timing to be affected somewhat by this tweaking. As I adjusted idle speed, I sometimes found the timing advanced a bit. Moral: before adjusting, set the timing and keep an eye on it while tuning. (2) Instead of adjusting open loop at 2000 rpm, you might suggest they pick the rpm they'll be smogged at (2500 in some States?) [I couldn't adjust the idle much higher on my car with the idle adjust screw, but with an assistant or other technique, this is a good idea. -JG] (3) Probably a typo but our cars are L-jetronics (L for "luft," German for air); early Bosch injection on VWs were K. (4) Have you watched your meter with the O2 circuitry connected and driving the car around? It's quite interesting. At idle, the mix alternates from rich to lean about once a second or a little faster; at speed, it's about 5 or 6 times a second. It's also a good idea to drive around for a while OPEN loop with the meter connected and see how the car performs in lots of conditions (cool mornings, or hot afternoons). You'll be surprised. [Jim noted in an earlier communication that he bought a cheap air/fuel meter from JC Whitney that was convenient for this purpose. I couldn't find one in the current catalog.] (5) Another advantage to making your two adjustments is that the O2 feedback control circuitry will be working more in the mix *midrange* On my car, the feedback was always JUST managing to keep the mix OK (it only has a limited range it can control). Consequently, on average, I was running lean because I was lean open loop. (6) the O2 sensors are very much like transistors and are not linear, mostly rich or mostly lean and spend VERY little time in between. The feedback controller in the ECU works on this principle (my wife says it's a "bang bang" controller). All the ECU wants to know from the O2 sensor is one thing: too rich or too lean? By always alternating (rapidly) back and forth between the two, on AVERAGE the mix is right. The trick is to set your car up so that the operating conditions are equally rich and equally lean without the sensors so the ECU can work right WITH them connected... Joe Gorin Jim TenCate Optimizing FI Tuning/Reducing Emissions 6 June 1995 I have one suggestion to add to your list of items to adjust for optimal mixture. The TR8, in contrast to the TR7, has an adjustable throttle potentiometer instead of a throttle switch. This reads the angle of the throttle plate in a manner similar to the way the air flow meter reads the position of the measuring flap. This sensor has three screws that can be loosened and the sensor rotated several degrees to change the input to the ECU for a given throttle opening. Turning the sensor clockwise will tell the ECU that the throttle is more open and it should supply more fuel, enriching the mixture. These settings will affect the overall mixture and should be included in any general "tweaking" procedure. Fred Smith Brisbane, CA Rough Idling 5 May 1995 The car runs very well throughout its rpm range, accelerates smoothly, etc., but does not always return to idle. The idle is set to about 800 rpm but many times will come back down to 1100-1200 rpm after running and maybe will then settle down to 800 rpm after some idling time. This mostly happens when the car is warmed up. Any ideas? My car did that too, especially in Austin when driven in hot weather. My Taurus does it too to some extent. Unless your decel. valve is bad (not likely), it's just the fuel injection keeping the idle high to keep emissions/mixture tolerable. I wouldn't worry about it unless it takes a LONG time for the idle to drop. Is everything else stock? Besides checking the decel. valve, you might disconnect your O2 sensors and take the car to your local smog shop and have them check the mix (tailpipe sniffer) without the O2 sensor feedback. Or you can try checking the mix yourself with an air-fuel mixture meter connected to one of your disconnected O2 sensors (ask us about doing this first). You can adjust the idle mix to nearly ideal by tweaking the clamp down point for the torsional spring inside the air flow box. Remember, that spring is now nearly 15 years old and you can't expect it to have the same spring constant as it did when new. Mine needed some correction and I believe the hot high idle problem went away (and now I sometimes get a really LOW idle so I haven't got it quite right yet). Happy tweaking! Jim TenCate, Santa Fe, NM High Idle Speed 9 May 1995 Try checking your vacuum advance/retard capsule on the distributor. If this unit does not work, the spark advance will be controlled solely by the centrifugal advance. I have a Mallory Dual Point distributor (but not for much longer) with mechanical advance but no vacuum advance or retard. It won't let the idle drop below 2000 rpm unless I drag the rpm down below 1000 with the clutch. Then, it drops to 850 rpm. I'm planning on replacing the distributor with a stock unit because the engine braking is pretty much non-existant without any vacuum advance/retard control. Tim Buja Rockford, IL High Idle Speed 9 May 1995 This theory makes a lot of sense to me. Also, the plate for the vacuum advance which is under the module, gets really stiff over time. The amp module should be removed and the advance plate dismantled and regreased to allow it to move more freely. Also, the centrifugal weights could be sticking and causing too much advance (which caused the engine to run faster) after the engine slows down. Fred Smith Brisbane CA Optimizing F.I. 7 June 1995 Summit Racing Equipment, 216-630-0200, lists a Cyberdine "Analog Air/Fuel ratio" gauge in their catalog, PN CYB-7009 for $29.69. This gauge can be connected to the exhaust sensor in parallel with the computer lead and will give a readout of what is happening to the mixture. The ability of this sensor to measure anything but Rich/Lean relative to the ideal 14.7/1 ratio is disputed but drag racers are using this same sensor to set open loop mixtures on expensive engines with good results. There is a posting on this under the title "O2 Sensors" at the GM F Body Home Page. I have just set up carb jetting on a new carb using a sensor from the junkyard (free) and the above gauge. These sensors are generic and the calibration is the same so they are interchangable, the single lead ones are unheated and those with 3 leads are heated making them less sensitive to their location in the pipe. The sensor I got uses a welded in bung, 18mm or opened up 3/8" pipe nipple, but there are some which have a flange with 2 screw holes which may be easier to install. The sensor is located in the reducer after the header, about 15" from the nearest port. It seems to work well and it correlated well with plug readings so I'm inclined to think it ties to reality. One thing to remember, it is reading the exhaust gas, not the mixture incoming, so if there are ignition problems, air leaks, etc they will affect the mixture being read. Careful. The lean burn sensors ARE different and a little more linear than the classic single lead variety you can find most anywhere. Joe Murawski, Attleboro MA FI Air Flow Meter Numbers 18 May 1995 Bosch Number Vehicle Fitted To Pins 0 280 150 186 TR8 X919 Lucas experimental 7 0 280 202 008 TR8 (Range Rover 6/70 to 6/86 ?) 7 202 016 TR7 FI early '80 7 0 280 202 022 Unknown - 7 202 023 TR7 FI '81 7 0 280 202 033 Vauxhall Astra/Cavalier 1800 4 0 280 202 036 Range Rover? 7 0 280 202 046 Rover SD1 Vitesse 7 Brian |
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Filters Charcoal Emission Filters 28 June 1994 When we got our car the bottom one (on the two-filter system) was completely full of gasoline, as the little screen that keeps the charcoal from coming out was clogged. This kept the car from idling and made for generally lumpy running. We carefully pried the bottoms off the canisters, cleaned them out and replaced the charcoal with aquarium stuff, epoxied them back together and now it runs fine (well, much better). If you unplug the hose to the filters and something changes, this could be the problem. Jody |
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Fuel Pump Pump Interlock 17 August 1994 Assuming this is a fuel injected car, there are several "interlocks"which are in the electric fuel pump circuit. One is on the air flow meter so if the engine isn't running or otherwise drawing enough air through the meter chamber to move the air vane off dead stop, that interlock is bypassed by the starting circuit so when the key is turned to the start position (to make the starter motor operate) the fuel pump gets connected to the battery as long as the key is in that position. To get around that for your purposes, you could disconnect the 12 V to the starter solenoid OR simply run a temporary 12 V lead direct to the fuel pump (with a switch in it) and only operate the fuel pump to run the alcohol through it. One note of caution, there is some concern that ethanol shouldn't be used in TR8's, so the same concern may be the case for using alcohol. Bill Sohl Pump Interlock - Dying inthe Heat. 7 July 1994 My car would die in the heat and then re-start after sitting awhile. I too, for awhile, thought it was a case of vapour lock but it wasn't the problem. It turned out to be the oil pressure switch. In carb cars it is tied into the electrical circuit sending power to the fuel pump. In theory, if the oil pressure falls below acceptable limits, the power is shut off to the fuel system to prevent damage to the engine. Its at least another area to investigate!! Good luck. Big Al Johnson |
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Fuel Types Oxygenated Fuels, Etc. 2 September 1994 I think I'm beginning to understand my TR7 and its Service Manual. Now, the operators manual says quite specifically not to use Oxygenated Fuels in the TR7. Perhaps you all have discussed this before I joined less than a year ago, but in case there is new information here, I'll tell what I learned. First of all, the service department at the place where Triumphs were sold, the place that sells Jaguars and Rovers now, acted like I was crazy when I asked how I was supposed to follow the recommendation of the manual and still drive in the winter when only oxygenated fuels, such as gasohol, are available. I took this as a sign that I shouldn't be too concerned. I did get a copy of a note written in Spokane, WA by (this is from memory but I can dig up the original to check if asked) a Porsche repair person about the same issue. His conclusion was that Bosch recommended against oxygenated fuels in their mechanical fuel injection design because of the increased corrosion of the mechanical parts with the more corrosive gasohol. Bosch then continued with that recommendation when they went to electronic fuel injection, even though they needn't have. It found its way into the Porsche and Triumph manuals from there, but we really needn't pay any attention. Joe Gorin Emissions, oxygenated fuels 30 August 1994 The warning in the TR8 Owner's Manual that prohibits the use of oxygenated fuel, apparently due to the heat generated in the catalytic converter. I expect that this is due to the fact that many oxygenated fuels are prepared using alcohol. Alcohol will attack rubber and aluminum if it's allowed to sit for a while. I suppose that if one doesn't drive his or her LBC over the winter months, it would be wise to either drain the tank and carbs or avoid adding fuel after the oxygenated fuels are required. Jim Babcock Emissions, oxygenated fuels 30 August 1994 We have been forced to use oxygenated fuel for the last 2 winters now, from Nov 30 to March 1 most of the IM240 areas have had this. This will be the last year for oxygenated fuel as we will now be required to have only re-formulated gas as of Dec 1 1994. To be honest I have not yet been briefed on the contents of re-formulated fuel, but I can guess it will burn lean like oxy fuel. It most likely will have oxy content. As you know oxygen causes the mixture to be in fact leaner. I don't understand how the chemists keep the oxy molecules suspended in the gas but they do! As I don't drive the TR8 much in winter I guess I have not developed any problem from using oxy fuel. I think if you go back to that time you will remember the concern was that a lot of oxy fuel was not manufactured correctly, causing engines to burn up etc. Also I believe another concern was the effect oxy has on rubber parts. We used a chemical called MTBE, which, in fact, is an ether. It costs more, so some of the smaller companies used alcohol to produce oxy fuel. Tim, beyond that you would have to talk to a chemist, and I'm sure several are reading this note, to get a better understanding of chemical compounds in modern gasoline. |
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Gauge Gas Tank Floats 15 August 1994 Tim Buja and Jim TenCate have been discussing gas tank gauges: The fuel gauge reading low sounds like a common problem (which I've got on my car too). Likely the float has finally started to absorb some gasoline. The float on my fuel-injected TR7 (and the fuel-injected sender is somewhat different from the non-fuel-injected sender, in that it uses one float for both the fuel-light switch and the fuel-gauge meter) failed in a way that looks like it should be common. The float is a plastic cylinder near the shape of a sewing thread bobbin. A side view: The float is attached to its mounting arm at the notch on either end. The mounting arm is much like a piece of coathanger wire. That wire has an end formed into a loop which is captured by the notch. The loop is not quite a full circle. The wire can have a sharp edge at its end, thus there can be a sharp edge, at high tension, pushing into the notch on the plastic float. This edge, on my car, eventually wore a pin-hole in the plastic. The plastic eventually filled with gasoline. The float became a sink. My attempts to repair, rather than replace, the float were unsuccessful. I tried epoxy (it dissolved in the gasoline) and opening the hole and patching with "gas tank and radiator epoxy." The latter lasted for two years. Perhaps someone can come up with a better repair technique. I replaced my float with one from a junkyard, and smoothed the edge of the wire arm as well. The junkyard float did not show any evidence of starting to get a pinhole. Joe Gorin Santa Rosa, CA Repairing Pin Holes If I were repairing a pin-hole, I would try melting the plastic with a soldering iron, and pushing the molten plastic over the hole. Of course you risk making the hole even bigger. Peter TR7/8 Fuel Senders 31 May 1995 The resistance readings of the fuel sender in the empty and full positions are: Empty = 320 ohm Full = 15 ohm The switch for the light has a resistance of just a few ohms when empty, a few hundred on the threshold of turning on the light, and is open when full (multiple megohms). Joe Gorin |
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Injectors Injector Life I read that Jim TenCate replaced most of his TR8's injectors one or two at a time. I would be glad to replace mine if they have a wearout mechanism and should be subject to preventive maintenance, but I don't see why they should. At 30 kmiles, about 6 years ago, my TR7 was running a little rough. My mechanic put some injector cleaner in the fuel tank, and I followed up with more treatments every few thousand miles, and everything seems to be good. I recall reading that in the mid-eighties clogged injectors were the subject of conflict between the auto manufacturers and the fuel suppliers, but that modern formulations of gasoline are not prone to clogging injectors. I haven't treated my car to cleaner for three years, and am experiencing no problems. So, my questions, especially for Jim, are: * What are the symptoms of a bad injector? * Are injectors still going bad, or were they just dirty? * Do you recommend replacing them at any particular age? Joe Gorin Fuel Injector Lifespan 14 February 1995 "Bad" injectors usually mean crappy idle. Maybe flooding hard starting. If the resistance measures fine then they have clogged filters or goo on the tip. There are a variety of tests that can be done quite simply: 1. Drip test. Pressurize the system and gaze at your lovely injector. 2. Spray pattern. Fire the injector with a magic box and examine the spray pattern for symmetry, small droplets of spray. 3. Flow. Again fire the thing for some number of pulses, collect the gas and compare to the others. If it passes these tests it's fine. 1 is dead simple to do. 3 is easy with a magic box and measuring cup. 2 is a bit dangerous and really should be done in a special setup. I'm in the process of building a magic box for testing for later 15 ohm type injectors. The TR8 injectors are the early type with the ballast resistors (yuck!!!). There are places that will flow and balance your injectors for you for a price. Some times a lot cheaper than new ones. Replace the little o-rings when you put them back in. Rod Barman Fuel Injector Lifespan 15 February 1995 They don't seem to fail mechanically. They DO start to leak at the plastic/metal seams after about 15 years and 75k miles on them though) You've only got four of them and if you're going to replace them, do them all at once and you shouldn't have to worry for another 15 years or 75k miles, whichever comes first : All mine are now "new" and haven't had a bit of trouble with them so far. I've NOT had any trouble with clogging, dirty injectors and I'm not doing anything special either. Fred Smith occasionally dumps in a can of something into the gas to keep his clean. The other way to clean them takes a little work. The problem with dumping something in the gas tank is that it also tends to clean up crud in there and pass it along to the injectors. The way I'd like to do it was outlined in the now defunct Performance Engineering magazine. You essentially replace the tank/pump/line to fuel rail with an external setup and then pump the cleaner through only the rail/injectors. Too much bother for my tastes (unless I start getting serious about this autocross stuff). Jim TenCate Fuel Injector Lifespan 15 February 1995 Another system I've heard of for testing fuel injectors is taken from the manual for my old Rabbit Diesel, How to Keep your Rabbit/Scirocco/Jetta Alive (by memory). The VW Diesel, BTW, has mechanical fuel injection. The procedure is simply to loosen the pipe to each injector while the engine is running and compare the drop in running quality (just like pulling spark plug leads). I was able to sucessfully identify a bad injector this way. Of course, just like the spark plug method, this it dangerous, because you must protect yourself from the possibility of fuel spraying on yourself. However, I suppose that with electrically controlled injectors you could simply remove the electrical connector (assuming it wouldn't destroy the ECU). Vaughan Scott Fuel Injector Lifespan 15 February 1995 If your injectors do start to leak at the plastic/metal seam, you do not have to replace them. I've had really good luck just fastening a fuel hose clamp right above the seam where the hose attaches to the injector. It fixes the leak but does not affect the fuel delivery to the engine at all. A 20 cent clamp looks really attractive after pricing new injectors. Barry Fuel Injector Lifespan 16 February 1995 To check for bad injectors I simply used the spark plug method itself. Watch the drop in revs when you disconnect a spark plug. Supposing that all plugs ignite properly (which is easy to check) then a drop in revs means that the injector is o.k. This way I found a faulty injector that sprayed continuously. BTW I had to replace the injectors also because of leaks in the body. I have tried various sealing compounds, but without success. Gerjan van de Walle Fuel Injector Lifespan 16 February 1995 Another point of failure, which is probably heat related, is the hose on the injector itself. Two of mine are becoming porous over their entire length. This is not evident unless the injector is pressurized, when it takes on the appearance of one of those leaky drip watering system hoses - little globules of gasoline (like sweat) will form. I've priced replacements locally (one of the few things I can find around here) new units are $43 with core exchange, and reconditioned units for about $22. I had never heard of reconditioned units, but this is from a very large and reputable parts house in the southeast US. Randy Ponik Fuel Injector Lifespan 16 February 1995 You can replace just the hose. Remove the injector and, with an exacto knife, carefully cut the hose away from under the metal crimp ring. When the hose is removed the ring will fall off. This will reveal a male end with a "christmas tree" fitting. Then you can put on an appropriate length of FUEL INJECTION (not ordinary low pressure line) high pressure hose and secure it with a clamp like the one to the fuel rail. Fred Smith Fuel Injector Lifespan The TR8 Repair Operations Manual states that the lamda (oxygen) sensor should be replaced at the D and E service intervals ie. 30k, 80k, 110k, 140k and 50k miles |
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Modifications CR & EFI 4 July 1994 I'm under the impression that the Bosch L-Jetronic EFI system tends to lean out over 3500 RPM, therefore any modifications that would require more fuel on the top end would cause problems for the ECU, and auxiliary fueling may be required should the fuel requirements be changed to drastically. I'm also under the impression that if all else remains equal, an increase in Compression Ratio (C.R.) for any engine will require the fuel system to be leaned out. Reason being that the increased cylinder pressure prior to ignition pushes the Oxygen and Fuel molecules closer together, (argument sounded shaky to me too the first time I heard it) thus requiring less air to fuel ratio. This I believe goes for Carbs as well as EFI. So It seems to me that the one really effective modification we can make to a Rover EFI V8 (with 8:1 ish CR), is to increase the CR, within the locally available fuel quality limits. Mark Elbers |
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Nitrous Oxide Boost 26 April 1995 The four-barrel Holley and initial NOS equipment came from Summit Motorsports in Ohio; I don't recall the address, but I'm sure someone in the group has it. Used a 390-cfm carb; don't want to use a larger one. And it mounts "backwards," not that it matters. The NOS set-up from Summit needed some parts not available from them, but I got them from NOS itself. This was several years ago, and I don't recall the details. The set-up I wound up with has a little module that sits on top of the carb and blows down into it (I think the set from Summit had a plate that went under the carb and caused clearance problems; I seem to recall now that NOS took it back for credit and sent the new parts). Summit also supplied a neat-looking triangular-shaped foam air cleaner from Edelbrock. Some say the round ones are more efficient; p'raps so, but they don't look as good (hey--that can be important...). The Offenhauser manifold came from Eight Parts in Arizona. I also put in a cruise-control system from JC Whitney. Don't laugh--it looks good, it was easy to install, and IT WORKS. A bit more about the nitros stuff: The set comes with several nozzles. Don't be greedy--use the smallest, and save your engine. Get thermal fuses from Radio Shack to cut off the system in the event of a fire. And keep several around, in case of backfires (they mount in the air cleaner). The bottle sits in the trunk, though not perfectly longitudinally (a bit of an angle); I drilled a hole in the trunk floor and ran the nitros line out that hole and down the driveshaft tunnel. It's a shielded line, and that was no problem. Doug Hitzig, Cocoa Beach, Florida |
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Plenum Chamber Some serious TR7V8 modifications ...... 2 March 1995 The downside is that the plenum chamber (overrun valve) fouls the bonnet release mechanism and so the heater air scoop cannot be fitted. Actually the US SD1 plenums are orientated the same as the UK models, with the throttle on the left. However the plenum is designed so that it can be used either way. It's the same part as on the TR8, which has the throttle on the right side. The holes are drilled so that the throttle linkage and the potentiometer can be fitted to either side. The only differences besides the throttle linkages between the TR8 and the Rover systems are the configuration and layout of the various hoses. By the way, I believe the US spec plenum has a smaller throttle bore, so using it instead of the Vitesse unit could impair engine breathing and reduce performance. Actually, I've been toying with the idea of putting a Vitesse plenum and intake manifold on my TR8 to get some extra power. I called several breakers yards in the UK but they wanted a lot for a Vitesse system. Do you know of any that are for sale for a reasonable price? Or would your friend be willing to trade a Vitesse system for a US system? Just curious. Fred Smith TR8 Plenum Chambers 3 March 1995 Currently, there is a lot of talking about V8-engine related stuff. I don't feel I am an expert, but I have seen and read a lot as I am rebuilding my engine now. Plenum chambers: The higher performance that you can reach with a Vitesse chamber is not in the bore of the throttle, but in the shaping of the "trumpets" that go to the inlet manifold. These have superior flow properties. The TR8 manifold is just a flat, square, and very restrictive junk of aluminium. I talked with someone at Roverparts UK and he says that you can gain at least 20bhp by using the Vitesse plenum. The main problem in my opinion is that the Vitesse chamber is a couple of centimeters higher and wouldn't fit under the bonnet. Frank Benschop, Amsterdam More Power for FI Engine - 5 April 1995 The Vitesse is not compatible with catalytic converters. The ECU does not have the circuitry to take readings from the oxygen sensor and the EGR valve. It was designed for the UK where it is only now that catalytic converters are mandatory. I came across the man from Lucas who designed the fuel injection system for the TR8 at one of the UK TR Drivers club annual meetings. He spotted the purple markings on my air metering unit and wondered where I had obtained it as they were Lucas factory markings. He has bought a TR8 fi US car for " old times sake" as he worked on developing the system. In order to increase the power output from the engine more air is needed in the plenum chamber. The one in the TR8 is essentially flat - about a 3" profile. The Vitesse plenum is similar to the ones on a Range Rover or Land Rover with fuel injection. It is about 6-7" in profile (having a domed top) and mates to a different inlet manifold. This has circular ports rather than the rectangular ones on the TR8 (and US / Australian Rover Sedan V8). The 3.5 V8 fuel injection was first tested in the TR8 Rover Sedan format. For increased power the Vitesse began a new evolutionary route. There have been 3.9, 4.2 and now 4.5 litre engines all using a similar plenum (ECU, air metering unit, potentiometer and other parts are now different) to the Vitesse. I asked Albert Tingey (the Lucas man) how to increase the power output. More air was his answer - hence the Vitesse plenum. Increasing the compression ratio would not do much. I am not hampered by the emission control equipment and have different (less restrictive) exhaust manifolds. I also have a **' 82 NAS '** ECU (although I don't know what difference that makes). The early fi cars were claimed to have a 137 bhp output and for later fi TR8s the figure rose to 148. I do not know what the 82 year might have been (nor could Albert remember). I have seen two Vitesse engines in converted TR7s. In one it did fit (just) but the whole engine must have been lowered as there is not enough clearance under the hood (bonnet) with the raised dome of the Vitesse style plenum chamber. In order to fit the engine in the other car it had been mounted well back and so the air scoop could not be fitted. As a result it became rather warm in the car (especially as it was a coupe) and also suffered from engine fumes. The other problem is that all the ancillaries are 180 degrees opposed. Although not insurmountable it would mean refitting the air filter box on the (US) drivers side, the potentiometer and other parts would also need to be turned (extending the wiring loom etc). In reply Fred wrote: Thanks for the reply to my query about the Vitesse injection system. Mr. Tingey's recommendation, "more air" confirms my hunch that a Vitesse system would be a good improvement on a TR8. The O2 sensor problem could be solved by using the TR8 ECU and a US spec Rover 3500 wiring harness. The TR8 ECU ought to be able to detect the additional air brought in by the Vitesse induction system and supply the required amount of fuel. The only real problem may be the EGR system. Fortunately, this does not interface with the ECU as it is controlled by manifold pressure. A topping would have to be drilled in the Vitesse throttle body and a pipe run to the EGR valve. I looked at my car and there seems to be several inches clearance between the hood (bonnet) and the top of the plenum. I read an article about someone who put a "double plenum" system on a US spec TR8 and it said that it "just fit with a little filing of the end bolts". Perhaps some subframe spacers will take care of this. Having the ancilliaries 180 degrees out will be a problem and that means that the air conditioning system will have to be removed to make room for the air flow meter and air cleaner, but I rarely use it anyway. The # on mine is Lucas 4 CU Fuel Control Unit 83617A. This is the same one on all fi TR8's and US spec Rover 3500s. I know they changed the reported hp output, but there are no differences between the components on the 80 and 81 cars. I am also wondering if your air flow meter is the same as mine. Mine has part # Lucas 2AM air flow meter 73173A. Also, on the heads, are they Vitesse heads? I understand that these are modified from the standard TR8/Rover heads in that they have waisted valve stems to provide better air flow. If so, then you have something good there. I have 3 ECUs - the one that has large purple letters 82 NAS has no other markings or number The space where the number should be has been blanked out. I have a new TR8 ECU - 83617A. The Vitesse ECU is part number 83986A. The 3 air flow meter part numbers are (purple markings) 73173A, Vitesse 73243A and the third is blank (again!). However there are also Bosch numbers for these and a friend's TR8 has number 0 280 202 008 (he has a new air flow meter with Lucas number 73173B, same Bosch number). The Bosch Vitesse one is 0 280 202 046 whilst mine with purple on it is 0 280 150 186 despite being Lucas 73173A. The third one is marked 0 280 202 022 which someone has suggested is a TR7 air flow meter. The size of the Vitesse air flow meter is the same as the TR8. The TR8 uses 2 different heads - carb and fuel injected. The part numbers of the fuel injected ones are identical to the ones on the Vitesse. I am also pretty sure that the valves are the same although as the Rover was still being made in 1987 they may have modified them again for later models. Certainly the Vitesse used a different distributor system - the 35DLM8. I am pretty sure that the Vitesse ECU is set up differently to a TR8/Rover 3500 one. Using the TR8 so the oxygen sensors work may well have a side effect. There is a company in the UK that has remade the twin plenum chambers, but they are expensive! Albert Tingey also told me that they were not as reliable - basically it was for racing. There are 2 books written by David Hardcastle (published by Haynes) all about tuning the Rover 3500. I have one of them (in store in UK) where an MG V8 owner had taken off his carbs and used a TR8 fuel injection system with 10.5:1 pistons and produced a large power output. This conflicts with what Albert says - but since he worked on the system I prefer his thoughts. Air is the key! Brian Ridley-Jones |
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Potentiometer Potentiometer throttle: 3 March 1995 They are very simple to adjust. At home I have a Rover training guide on the Vitesse. The only adjustment you have to do is to position the potentiometer such that it has a certain resistance at zero throttle (engine off). I believe that certain resistance is 900 ohm, but I can look it up. The total resistance is 4700 ohm or twice that value, I forgot. Only part of this range is used, so full throttle will give only one half or one third of the total resistance. Frank Benschop |
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Tank Tank Replacement Getting the tank back in is a job. Two people would help, but I was able to wiggle it just into place by myself, with patience. I put a rubber pipe cap on the LH shock absorber stud to protect the tank from scrapes before putting the tank in. I decided to put these caps on both shock studs when done to protect them from corrosion (although I have problems with rust since leaving Chicago.) It comes in white, black, almond, brown, etc. It is very thick and very flexible. I bought a four foot strip, 2.5" wide for about $4.00. I cut off the curved portion which meets the floor. It has adhesive attached to it already so I cut it to length and stuck it to the tank straps. I will get to see how well it holds up over the years. Does anyone know if vinyl is appropriate for this use? Put the rubber filler neck on, and the vapour hose, before installing. It should point straight up if the tank is sitting flat on the ground. After the tank is in place, you can feed the metal filler pipe into the rubber neck, although this is tough. Do this before you strap in the tank as you want some freedom in movement. Once you get it in, bolt the filler neck to the body to help locate the tank. Try to minimize scratching the tank, but face it, you will scratch the tank re-installing it. I just touched it up with spray paint after it was in position, but before I installed the straps. Write down what wire is connected to what, then don't lose the piece of paper you wrote it on! I can't figure out which wire is which! When you are connecting the radius rods, you will be faced with the standard suspension problem that the hole in the rod does not line up with the hole in the body. Since this is just about the last step in the process, the shocks are already connected. You will find that jacking the axle at the differential rotates the axle such that the input shaft of the differential goes up, then the radius rods move rearward. Letting the axle drop to the full extension of the shocks rotates the axle such that the input shaft goes down, and the radius rod moves forward. Playing with that last quarter inch of axle travel, you will find a position where the radius rods holed line up with the body. Again, two people would be handy here, but with several iterations, I was able to find a position where the bolt slid into position without violence! I disconnected my drive shaft, but I don't remember why. I think I was worried about over flexing the CV joint. Is that a real problem? I completely disconnected the parking brake cable to get it out of the way. The ROM make no mention of this, but it looked like there wasn't a chance of getting the tank out with the cable in the way. I hope my experience helps the job go more smoothly for others. This was not nearly as horrible a job as I expected. If I had thought to use an impact wrench on the tank straps, it would have been almost an easy job. If you are willing to disconnect the brake hose, it should be a piece of cake! By the way, use an air impact wrench! Also, I use a sealed fluorescent light when working under my car. You do not want to be under your car with electric motors, breakable light bulbs and gasoline vapours! Gas Tank Removal I have yet to re-install my tank, but I did undo the last tank strap bolt this weekend. After fighting with those stud-nut arrangments for several hours, it finally dawned on me to use an impact wrench. So this weekend I climbed under my car and in 15 seconds the last nut was out! So, BIG TIP: use an impact wrench to remove youy fuel tank stap nuts. You will do a lot less damage to the car, tank and straps that way! I have been scratching my head trying to figure out what to replace the strap pads with. I suppose I could scrounge up an old piece of timer inner tube. Another idea I had was to use carpet tape. It is about the right width, fairly thick and soft, and it is "aggressively" tacky. Only problem is it is white rather than black, but the fuel tank is pretty much out of sight on our cars. Peter |
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