Okay, so here's the deal. I just bought a 1994 Firebird trans am. 5.7 lt1 The car has 123xxx Supposedly the engine has 10,xxx but I'm not sure. I got it two weeks ago. And has been great!!!! Until recently I was driving and it cut out. I pulled over And About 2 minutes later it fired up fine and drove regularly with no problem. Later That evening. I happened again. Once again, waited About 2 minutes and fired right back up. This time 10 minutes later it died again And I had to wait About 15 minutes. And it kept happening until I made it home. I replaced the coil. And it ran perfect for About 45 minutes. I drove it enough til I was confident it was fixed til.That night the weather was About 65. But I drove it long enough for the car to get hot I drove it to school this morning no problems After school. No problems. I drove it for about 10 minutes. It died.. after it died. It fired right back up. Idled for about 30 seconds And died. Happened 3 times.. I checked to see if it was getting any spark. And nothing. No spark. I read something About an icm, so I replaced that. The car drove the whole day, I drove everywhere that day, ran fine. Then that night on my way home, it shut off, onvce again no fire…..
The car will idle for 2 days without dying. Lol.
So basically it happens when driving.
Checked most connectors I could find.
All seem good.
Grounds seem good also. (actually couldn’t really find many at all)
I added 2 grounds, One from battery to frame and 1 block to frame.
Theres the whole story, it happens when driving. Its happened from a stop then when I go to take off it happenes.. like I said, sometimes it will go the whole day driving good but others itll drive 10 minutes.

please help!
like i said, new coil and ICM
the opti also looks brand new but but i dont know f it actually is.

 

Well obviously you have spark or it wouldn't run at all. You said it idles fine but cuts out while driving. Seems like it could be intermittent spark failure or something in the Fuel delivery system. Maybe your pump beginning to fail. This is a stumper.

 

I'm sorry, I should have said, it loses spark when it cuts off.
While its dead I ran a spark test And a fuel pressure test. It has good fuel pressure. But no spark.
Like I said, I've replaced the icm and the coil.

 

First off, I just want to say. I know your pain...very well. I had the EXACT same issue, i chased it with all sorts of parts, Fuel pump, FPR, ICM, Coil, plugs wires, finally i decided to change my opti and on my way to taking it off i found the opti harness plug was completely destroyed. Corrosion, a corner was chipped off of the cavity, it was bad. After that i ordered a new one, buttoned it all up, and I was on my merry way. Never had an issue since

 

my harness looks good. I checked it out. No currosion. No broken parts.
But I still think it could possibly be that.
I'm going to check it for continuity tomorrow night. (When I get home)
I was also told it could He the pcm/ecm. So tomorrow night I'm also going to change That (a friend is letting me use one for testing to see if my problem lies there)

 

Im having the same problem in my 93!!! I just replaced the fuel pump and tried to get it running, after many attempts it finally started, for about two mins.. when it shuts off it has no stumble just like you turn the key... same parts are good on my car as well

 

It turned out, My Opti was bad.

 

Ya that's what I am fearing...

 

Yeah. I think everyone does.
The labor isn't really difficult. Just some time consuming.
And no one wants to pay the price of an opti! I know I didn't.
My opti had 10k on it. But it was an eBay opti. And they are a waist of money. I went with one from advanced auto parts.
But I was told MSD can totally rebuild yours for like $130

 

How did you go about getting it out? Do you know of a good write up anywhere?

 

Having a 4th Gen. You should become very formilure With "shbox.com" it tells you just about all Of the how to's And etc. Check it out.
But, honestly I want at it without the site.
I removed the electric fans. For a little more play room.. also the harmonic balancer, I heard u can do the job with it still on. But its way easier when its removed. you have to remove the water pump. After you remove it. Its easy from there. You take off the opti And end of story. You don't have to worry About the timing. The opti has a little notch that does into the crank that you can't mess up. It Just slides in. When you put on the new opti make sure you align the notches (one slides in the other) And then once you put the water pump back on. Etc. Make sure when your done you bleed the cooling system. If you don't. You'll run hot. You must use the bleeder screws.
Any more questions feel free to ask. I'm 17 yrs old and I did it all in an afternoon. Lol