'94 Impala SS stalls and won't fire

[sinSStr]

Okay, we're working on a '94 Impala SS with about 200,600 miles on it. The issue we're having started about 500 miles ago. Car comes to me (friend's car) with a very high idle. Key on, there's no check engine light, and no communication from the scanner. Bang the PCM around a bit, now the car idles fine and the check engine light is on with the key on, engine off. I should note that his factory air box, which the PCM normally sits flat under, was gone when he bought the car 4 years ago. It's been sitting at an angle against the inner fender since then. A couple weeks later, on a rainy day, the car starts stalling. Sputtering like it's running out of gas, and then just dying. Cranks like hell but won't start. Let it cool off for 15 mins, starts, and runs for about 30 mins, then it dies again. When it's dead, we find out there's no spark. Pull the opti, find coolant in there, replace it with a Borg-Warner one. Water pump had been replaced about a month prior to this with a Bosch new replacement. He leaves, and calls me 30 mins later saying it did the same thing. Gets it to start, brings it back to our shop, it dies while idling and loses all communication with the scanner again. Get a new used PCM for a '94-'95 Impala, reflash it, install it, and secure it. Now it's fine for a day and about 100 miles. Same thing. Sputters and dies, and won't fire. At this point it won't even turn over. We tow it back, put a new battery in it (had a dead cell), and it fired up and ran. Just for kicks and his/everyone's satisfaction we install a new Borg-Warner ignition control module. He takes it home, drives it another 100 miles, and today it dies again. This time a little different. As he was turning a corner, and accelerating normally, it was as if the key were just turned off. No sputter, no loss of power, just flat out died. Let it sit for 10 mins, it started back up, he drove it back, and I brought him to work in my car. I let the car run in the shop for 2 hours, took it out for a 10 mile drive, did a couple WOT runs, medium runs, slow runs, and yet it never died. WTF is going on?! Every ignition component minus a coil has been replaced, yet it still dies and has no spark. With the exception of today, every time it's died has been under normal acceration from a stop, and the engine has been warm. Day one of the stalling was rainy, every other day has been dry. Engine is stock (replaced last year) except a cold air intake and the home plate delete. Any help with this would be greatly appreciated. I'm at a loss right now. This car is killing me.

Cliffs: Car stalls when warm and won't fire (cranks though) and it's not fuel related. Opti, control module, and PCM have all been replaced.

[Fixxer99TA]

Try swapping in a coil you know is good just for kicks.

Sounds like you solved some of your problem, but not all of it. So the initial issue was really a few issues acting as one.

If its not a coil, and you have replaced every other possible part, I would start looking for frayed/grounded wires.

["97z]

Vehicle Application:1994 Chevrolet Corvette 5.7L1996 Chevrolet Impala SS 5.7LCustomer Concern:The engine stalls and will not restart at times. When it will not start, there is no spark.
Tests/Procedures:1. Check for a 5 volt reference going to the distributor on the Red/Black and the Purple/White wire with the distributor disconnected.

2. If reference voltage is not present, check the wires for a open or short back to the Powertrain Control Module (PCM).

3. If there is a 5 volt reference, then hook everything back up and check for a 0-5 volt square wave on each wire one at a time with the engine cranking.
Potential Causesefective Distributor
Defective Powertrain Control Module (PCM)
Open Wiring
Shorted Wiring

Diagnostic Codes:None
Author:Christopher Pittman Average Reported Mileage:84000 Confirmed Fix Summary Confirmed Fix2 - Distributor

[sinSStr]

So potentially a defective opti, eh?

[StangeatinZ28]

So potentially a defective opti, eh?

that's where i'd start

[sinSStr]

Update: So, the car has been with our master tech for the last 2 days (he's been taking it home) trying to get it to die again since the day after the ICM was replaced (this is when it last died). He couldn't sleep last night so around midnight he took it out and it died immediately upon getting on the freeway. He had both a spark tester and fuel pressure gauge with him, and it turns out he had no fuel pressure. Primed, and primed, and primed, and primed, and finally got enough pressure to start. Turns out the thing had two problems. Not sure which of the 3 things (PCM, ICM, or Opti) caused the no spark issue, but we fixed it, and it has spark now and just needs a fuel pump. Car is Christine man, I'm tellin' ya. Ever since he hit 200k a couple weeks ago it's been nothing but problems.

[Fixxer99TA]

Ouch, good to hear you got it sorted out though. I hate the multiple problem issues

[sinSStr]

Yeah I just feel bad for him and I don't want him to think that we're hacks. We did everything in order of what we found and was all justifiable. Had it been one of my normal customers that I can't talk to like a friend, they'd prolly had blew their lid at me by now.