[Shotimes] Smog Woes

[Alan Fanning]

I've been too busy at work to make much progress on the car, but I did get a
new intake manifold gasket installed this week. I had mangled the previous
one after removing the manifold after my first smog test - now at least I
know it's not contributing to my woes.

Original test results with 80mm maf and lpm were as follows:

            Item    max/ave/meas
 15mph       HC     114/31/38
             CO     0.73/0.10/.01
             NO     785/237/1064

 25mph       HC     88/20/34
             CO     .61/.09/.01
             NO     724/199/723

So I have some HC I could "trade" for NO with some lpm programming, I
suppose. Not a very precise way of doing that, though, unless it can be done
in real time.

My subsequent test attempt was done on a rainy day with the OEM maf setup
(no lpm) and the spout plug pulled. That resulted in an aborted test, after
several attempts, due to difficulties maintaining a constant rpm. I think
Leigh's comment below regarding the AC system may be correct though - it was
raining and the defroster may have been on. The AC system on this car does
have issues that affect the rpm's when it kicks in.

The EGR passages are very clean. The back sides of the valves have a little
crud on them, but from my untrained eye it doesn't seem like a lot.

The intake tract is pretty oily, but I believe this is a typical result of
the PCV system, right?

Where do I get GM top cleaner and is this used in the gas tank or applied
directly thru the intake?

Thanks much,

    Alan


> Turn the A/C off, restart the car, and see if that helps. My compressor on
> my 89 was seizing intermentantly, and it thru off the idle control computer
> bigtime for over a year til I found it.
> To check for vacuum leaks: disconnect hose at engine, need hand held vacuum
> pump/guage, should hold.
> I've seen leaks in hoses, connections, fittings, vacuum tank in fender, and
> the vacuum pull hose for the cruise control down by the clutch pedal where
> it rubbed thru the hose by the steering gear (my 94 with dead cruise).
> Manifold vacuum leaks can be checked with a spray of some type at the gaket
> area with engine running.
> With all the mods you have you may need to check that your O2 sensors are
> good, and the mixture is right. Did you get CO readings during you smog
> check?
> Good luck
> Lee
> 
> 
> ----- Original Message -----
> From: "Alan Fanning" <Awfanning@earthlink.net>
> To: "SHOtimes" <shotimes@autox.team.net>
> Sent: Thursday, February 26, 2004 12:53 AM
> Subject: [Shotimes] Smog Woes
> 
> 
>> Between the weather (rain), work (12 hr days), and the SHO I'm about to go
>> 'round the bend. I figured I was a shoe-in to pass smog today with cool
> damp
>> weather and the SPOUT plug pulled. No such luck - besides running like a
>> pig, as you had warned, the engine wouldn't hold a steady rpm setting
> while
>> on the dyno and the test was ultimately aborted after several attempts.
> Last
>> time around (a couple weekends back) it seemed to hold rpm but wouldn't
> pass
>> on NOx.
>> 
>> I removed the intake last weekend to clean the EGR passages (didn't seem
> to
>> be clogged) and buggered up the gaskets in reinstalling the manifold. No
>> spares, so I just put it back together. No doubt this didn't help matters,
>> but one of the things that has puzzled me on this car from the get-go is
>> that, with the trans in neutral or clutch pedal in, I can't get it to hold
> a
>> constant elevated rpm below about 2000 rpm. It either scoots up or down
> from
>> the point I'm trying to hold. Seems like a connected symptom. Vac leak
>> maybe?  I've previously checked/replaced all the hoses and the intake
>> gaskets.
>> 
>> I've got about 5k on new plugs, plug wires, O2 sensors, IAC valve, and
> just
>> about everything else that is replaceable. I was running a 55mm MAF which
> I
>> believe to be good, and no LPM. Spec's include Stage 1 cams, SHOShop 3.2l
>> w/10.5:1 compression, stock manifold, new/rebuilt OEM-spec injectors.
> Engine
>> seems a little rough at idle, but I have no way of telling whether it's
> the
>> cams or something else.
>> 
>> Any help appreciated. I'm about to run out of time (and patience) here.
> It's
>> a pretty car but...
>> 
>>     Alan
>>     '91 SHO
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