[Shotimes] More on my issue
Arjun Khosla
shojun@mtrs.org
Thu, 03 Jul 2003 20:54:39 -0700
Four or five months ago I dealt with an issue where my tach dropped to
two thirds of what it should have displayed, and my engine was only
running on 4 cylinders (IIRC, cyls 3 and 4 weren't firing according to
the cylinder balance test).
The error code suggested the coil pack was shot, so I stuck a multimeter
on the connector going into the coil pack while the car was running, and
there was signal on all the wires. Intermittently the engine would go
back to 6 cyls for a couple of minutes, once in a while. Swapped the
coil pack, and the problem continued. Still intermittent-- at one pint,
it came back to 6 cyls for almost a week! Since I had power on the
leads going into the connector on the coil pack, I assumed the connector
was the problem. Couldn't get the connector, so I took a Dremel, zipped
mine apart, cleaned up all the connections, and epoxied the connector
back together. Ran the engine, and I was still on 4 cyls-- that was a
disappointment-- too much work, zero gained. Somebody on shoforum.com
suggested ensuring that I had a good ground on the coil pack, but that
didn't help me either.
The next thing in the line of suspects was the DIS module. Bought a
used one on eBay for $20. Swapped it into the car, and right away I was
back on all 6! ...For half an hour. Then I had 5 minutes as a 4-cyl
car. Then a few minutes as a 6-cyl. Then it was back to 4 and stayed
that way for a couple days of driving.
So I gave up and took my car to my mechanic. He spent half an hour with
me, the car was no longer listing any codes, he was confident that it
was the coil pack. He had to go attend to one of his employees for a
minute, and I noticed that the car was occasionally jumping into 6-cyl
mode. I lightly knocked on the DIS with my fist, and suddenly the car
was on 6 cylinders again! The mechanic shorted one of the spark plug
wires, and it was back down to 4 cyls. He whacked the DIS with a
screwdriver handle, and it was on 6 again. He said he was 99% sure it
was the DIS-- apparently he's never seen a case where a coil pack
operated intermittently, but he has seen it for a DIS, and apparently
he's seen a lot of Ford DIS modules go bad.
I ordered a DIS from a local parts supplier (CAD$165, for an aftermarket
KEM-branded module), returned the used DIS module to the eBay seller
(who was very nice about things and refunded my money), and popped in
the new DIS module. 6 cylinders is what my car's been running on for
the past three months now!
Ah, what a moneypit my SHO is! It's getting a "supercat" installed in
place of my resonator tube as we speak so that I can get it smogged--
it's a helluva lot cheaper than a proper y-pipe, and I'm planning on
selling my SHO anyhow... Today I was negotiating with a local Honda
dealership that has a used 93 ATX for sale-- they want a fair bit of
money for it, so I figured it was probably in good shape, so I took a
test drive with one of their salespeople, turns out it's not in such
good shape (needs suspension work, a 60K, and has some electrical
problems). I left it at that last week, and then this week I popped
back and made a very low offer on the car (accounting for all the work
that I think must/should/could be done). Apparently they're taking my
offer into consideration-- it's half of what they paid for the car, but
apparently they didn't inspect or test drive the car before they bought
it, since they bought it off of one of their parent company's employees...
Regards,
-Arjun
89 SHO
james@dhlake.com wrote:
> I checked it this morning and I get Vbatt on each coil line
>with both engine off and running, just for a test I checked AC
>voltage while the engine was running, I got a steady voltage on
>2 of the connections of around 2.2 and the third wouldn't steady down
>is that a sign of bad drivers? Is the solution Replace DIS module?
>I feel that I am almost to a running SHO again.
>
>On Tue, Jul 01, 2003 at 09:00:31PM -0500, Steve Weinrich wrote:
>
>
>>Yes, a coil fault can cause a tach that reads 1/3 low.
>>
>>The TACH signal (IDM) is a summation of hte three coil drive signals. If
>>there is a fault such that the circuit for one of the coils was open or if
>>the output driver in the DIS was defective, you would get this symptom.
>>
>>You can check for an open coil/connection by unplugging the DIS connector
>>that feeds the coil anf look for Vbatt (Ignition ON) at each of the three
>>wires. This will detect a gross open.
>>
>>Steve
>>----- Original Message -----
>>From: <james@dhlake.com>
>>To: <shotimes@autox.team.net>
>>Sent: Tuesday, July 01, 2003 12:46 PM
>>Subject: [Shotimes] More on my issue
>>
>>
>>
>>
>>>I think my problem has been ignition related all along.
>>>I forgot a symptom to add.
>>>
>>>symptoms:
>>>217 code in persistant
>>>tach reads approx 1/3 low
>>>cylinders 2 and 6 come up in dropout test
>>>
>>>All my O2 sensor issues seem to be caused by the ignition
>>>dropout.
>>>
>>>Is there anyway to test the DIS module?
>>>
>>>Now that the problem is back I will re-check the coil
>>>primary side, but could a coil issue cause the tach to drop?
>>>
>>>Another possible interesting fact, one spark plug blew out
>>>of the engine and I limped home on 4 cyl about 1 month before the
>>>problem started. The Ceramic blew out of the metal part, it was odd.
>>>
>>>James
>>>_______________________________________________
>>>Shotimes mailing list
>>>Shotimes@autox.team.net
>>>http://www.team.net/mailman/listinfo/shotimes
>>>
>>>
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>>
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