[SOLVED]Ignition Module?

Kaonix · June 01, 2009, 12:39:33 PM

Hi all, need a lil help. I tried searching but couldn't really find anything.

1990 TGP w about 130k

Driving home from work last nite and the car starts vibrating a bit under acceleration. I get off the highway and the car seems to be misfiring. Steadily. Doesn't stall. Doesn't try to stall. Rock solid idle over 500 just a constant misfire. I go out and check the coil packs to make sure they are firing, all are firing fine. Get a check guages lite occasionally but nothing regularly. No CEL at all. I pull the wires off each coilpack individually, looking for the one that doesn't change the way the engine runs and couldn't really pinpoint any change in the idle when pulling each wire. I smell raw fuel on occasion since this has happened. Good X-Pipe, no apparent vacuum leaks, and the car has been running/boosting fine. I have come to the conclusion perhaps ignition module/ECM? Where is the ignition module on this car? ECM is behind the trip computer? Any other ideas welcome. I'm usually a pretty good mechanic but as of right now I have NO tools and this includes a spark plug wrench. Nor do I have the cash to pay a mechanic. I need to diagnose this problem instead of throwing parts at it. If anyone can point me in the right direction I'd appreciate it. Anyone with a garage and some tools in the area (PHX, AZ) would be uber appreciated!

TGP Nick · June 01, 2009, 08:00:47 PM

The ICM is right behind your coils, if you pull it off, you can bring it to an auto parts store and have it tested.

The ECM is behind the black plastic shroud on the passenger side front fender.

Have you checked your fuel pressure?

I think I'm the only member on here that is in Phoenix, AZ as well :laugh:

Kaonix · June 03, 2009, 08:50:09 PM

Ok. Problem solved. After much aggravation, sweat (I live in phoenix) and burnt and shocked hands I've solved this problem. First plug wire on front of engine closest to turbo was grounding out on the metal tube that runs right in front of the wires. I spent NO money on un-needed parts! Very happy this turned out to be an easy problem to solve. Now. As for replacements. Any suggestions? or just get a universal set from Pep-Boys?

I do have one other question. When I'm driving the car with the air on, air blows cold out of front vents. When I start getting into boost the front vents close and A/C starts blowing out of floor. What causes this? Possible solutions?

TGP Nick · June 03, 2009, 09:16:53 PM

For sparkplug wires, I would recommend a set of AC Delcos. They aren't that expensive, and work well. That goes for all ignition components on these cars, stick with AC Delco parts. The sparkplugs are R42LTS.

That is actually normal. Your vents work off of vacuum, and when you hit boost there is no vacuum, so the vents are temporarily redirected until the vacuum returns.

flybynite · June 04, 2009, 05:25:51 AM

Quote from: TGP Nick on June 03, 2009, 09:16:53 PM
There is actually a 3 way tee with a 1 way check valve and it's located under the cruise control module. It is likely that it's malfunctioning or it not there. Your vents work off of vacuum, and when you hit boost that check valve keeps boost from affecting your vents...

Fixed.. :icon_biggrin:

TGP Nick · June 04, 2009, 12:55:27 PM

My car does the same thing with a new check valve in that location.. :dunno:

flybynite · June 05, 2009, 05:26:50 AM

I just had the same problem after the 5 speed swap. I found that I had the vac lines at that tee hooked up wrong. None of my TGPs stop blowing out of the vents under boost. Not sure whats up with you car though. I would check to see if you have it installed correctly or see if you have the correct part...

TGP Nick · June 05, 2009, 11:14:05 AM

Are you using HELP! #47150 in that location?

mfewtrail · June 05, 2009, 09:42:01 PM

You might not have your check valve routed right or the valve itself could be bad(even if it's nearly new).

EDIT: Or you have a vacuum leak. The vacuum ball in the front fender is what stores vacuum for hvac/etc. use during low/no vacuum situations.

Kaonix · June 06, 2009, 05:52:10 PM

wow, thx a ton guys. I'll need to look for this check valve and probably replace. I have a few issues with a couple of hoses on the car, there is one that comes out near the CC module that was cut by previous owner for some reason I think that might be part of the issue. Is there a diagram anywhere of the entire vacuum system for this car? I would search but question came as I was writing :P LOL, nevermind. soon as I hit submit saw the sticky with diagram. :icon_idea:

flybynite · June 08, 2009, 05:18:42 AM

Quote from: TGP Nick on June 05, 2009, 11:14:05 AM
Are you using HELP! #47150 in that location?

I am not sure, I have never had to buy one. I will look today and see if I have a spare.

jerry455 · June 08, 2009, 12:03:40 PM

I think that is what I used a couple of years a go when I repaired my vac. lines.