'94 lt1, stumbling on the e-way

[zeeman]

Yep, more problems. I ran out to St. Clair from Clinton twp today, on I - 94. a mile or so before Fred Moore Hwy exit my car kinda stumbled.... Like it was shut off for a second, then shortly after it did it again, this time I saw the gages come back up when it restarted. So it was off briefly. when I lifted my foot to take the exit it shut down. It took a few tries to get it to start back up, but when it did it started just like it always does, it hitched and bucked a little but got me where I was going.
On the way home I could hear it miss a little cruising down the e way, and it stumbled a few times, shut down 3 or 4 times, I only had to restart it once while driving it, and it started right back up.
I am getting spark knock at w.o.t. and it bucks here and there while driving it around town.

I dont really know the full history on this car as I have only had it a short time. So any ideas on where to start diagnostics would be helpful.

[nascarnate326]

look at the weep hole on the bottom of the water pump.

[zeeman]

okm.no leak. My guess is you are leaning towards a bad opti spark?

[nascarnate326]

exactly where I was going.

Electrical stuff usually doesnt just go out like that while driving. I can also say, the optispark is always blamed if any issues come up, many times its NOT the opti.

[zeeman]

thats why In would like to diagnose before I start throwing parts at it. As I understand it, an optispark is a few hundred bux. I would rather not have to do that and find out afterwards my car is still stalling on the e way.
So I am thinking, Ignition module. Opti spark. Fuel pump? Its not throwing any codes, no check eng. light. so I am rather stumped. where is the valve to check the fuel pressure?

[chrizar]

First thing I'd do is check plugs and wires, then test the ICM and coil, lastly the opti. But it can't hurt to check all the plugs along the way to make sure nothing is loose or burnt up etc. When my car acted up like that it WAS the opti after putting a new coil and icm on it. Even better if you can scan for any DTC's, may tell you something right away.

Edit- nvm on the DTC's saw your post after mine. and if I'm not mistaken the valve is on the back drivers side of the intake to check FP. never had to check mine, only pull the motor out a few times ha!

[Dummybait]

As others have said, check that ICM connection.

[JoeliusZ28]

if things are randomly cutting out the first thing i would do is check your battery connections including the power block and ground straps. If gauges are powering down this doesnt sound like an opti issue to me. voltage, temp, etc should maintain even if the engine is dying.

[zeeman]

I think the gages I noticed zeroing out were the oil pressure and the tach, all the idiot lights come on just like key on engine off when it dies like this. I can be cruising down the e-way with the cruise control set and its like someone reaches in and turns the ignition off. "Oh! were coasting? wtf?!"

after my new starter no start drama a few weeks ago, believe me all the cables are present, clean, and tight.
You may be on to something with the I.C.M. suggestion, It has occurred to me that every incident has begun just after reaching operating temperature. Matter of fact it seems to run better cold. less spark knock at w.o.t anyways. I 'll try to get the icm tested tomorrow.

[JoeliusZ28]

Sounds like youre on the right track

[Lucky SOB]

If that doesn't fix it, have the alternator tested. They can cause some funky issues

[Formula94]

I would have to say power distribution as well. I worked at an automotive electrical repair shop back in the 90's and a lot of GM models had bad ground connections. Seen it on f bodies, n bodies, Grand Prix bodies, s trucks and m vans. Usually tell tale sign of a ground problem was when the gauges would drop out or just act erratically. In most cases it was a corroded bolt and connection. Also have seen the ground bolt or screws just come loose. Check that ground connection on top of the passenger shock tower. Make sure it's clean and tight. Then follow the main ground down to the block. Make sure that is ok as well.

[zeeman]

Well, I had then I.C.M. tested today and that checks out ok. He did it 9 times.
It died in the driveway while idling today. It shakes at idle and up to about 2000 rpms. Not a lot, enough to be noticeable, I guess its a miss, it doesn't seem to be, but it is shaking a little. Its weird, it runs ok otherwise, no backfiring or anything . It just randomly dies. I want to just throw an opti at it just to get it over with. But damn the good ones are expensive!
If I do the opti I might as well do plugs and wires to.

[zeeman]

I borrowed my sil's Snap On computer, it does obd I. But I just found out I need an adapter. Damnit. I tried to take it for a ride, stalled out about a block from the house. Didn't want to re start, started, stalled again, finally restarted. It got beat on a bit after that. Backfiring, spark knocking, stalling.......effing car.....

[zeeman]

So, I jacked it up and crawled under it with a light. theres oil dripping out of the vent holes in the bottom of the opti. So I guess I get to tear it down. POOP!