kgkern01

iTrader: (10)

So I have an issue with my car I'm trying to track down, and it seems to be getting a little worse. The car will die about 10-15 minutes after cold start. I've spaced out the ICM, tried a new one, tried 2 different coils, fuel pressure is fine when cranking, it just wont start back up unless it sits for a long time, and when it does start back up it dies pretty quickly afterwards again. I tried data logging it the last time it did it, I didn't see any codes thrown or saved either. I'm tired of throwing parts at it, any suggestions?

Thanks!

hrcslam

When this happens check for 1-4VAC at pin B of the ICM connector while cranking. If nothing, opti or wiring to/from opti or wiring to ICM.

myltwon

iTrader: (1)

Fuel pressure does not drop off when it dies?

kgkern01

iTrader: (10)

Nope, fuel pressure stays around 40-43 with key on and when cranking.

smitty2919

If fuel pressure is staying OK, then I suspect it can only be spark that is cutting out.

So I would start looking into testing the PCM to ICM, ICM to Opti etc etc.

SS RRR

iTrader: (2)

Could be a long shot, but if you are still running O2's, unplug them and see what happens.

kgkern01

iTrader: (10)

How could the O2's cause it to just shut off?

smitty2919

When they warm up, car goes into closed loop.

myltwon

iTrader: (1)

Ignition switch could be another suspect.

any time a car doesn't want to run after being warm it's usually one of two things: failing electric component or related to closed loop.

kgkern01

iTrader: (10)

It happens well after the switch to closed loop.

kgkern01

iTrader: (10)

I've replaced the ignition switch as well last year. When the ignition switch goes out so does the dash and everything else. My issue is that it cranks and everything it just won't fire. I just need to know how to properly diagnose the ignition system/components to find the root cause.

atlantadan

http://shbox.com/1/4th_gen_tech2.html#opti_test
Edit: You said you logged it. Try logging it again from cold to when it dies. That may tell you what gave out and when

smitty2919

I would agree to log from cold start and let it die. Then go back in and see what happened.

May see the spark cut out then then the car dies.

kgkern01

iTrader: (10)

Just in case it turns out to be the opti, where is a good place to get a GM opti that is reasonably priced now that they are all remanufactured? Rockauto?

kgkern01

iTrader: (10)

I'll check the log from when it died last time a little closer, maybe I missed something.

kgkern01

iTrader: (10)

I just went ahead and bought a new opti wiring harness and AC Delco opti to rule out the connector (which didn't look great on the opti end) or the Autozone opti as the culprit. Whenever spring weather decides to come back I'll see if that resolves the issue. At that point I'll have new (reman) Delco opti/harness, new ICM, new coil, new wires.

Nastyc4

iTrader: (13)

This is becoming a very common and emerging issue amongst LT1s. My brother has a 94 z28 that does the exact same thing for years. It's not driven much so never really looked into it but I've checked fuel pressure (fine), replaced map icm and coil and no luck. Will order the harness for the opti as you did as well.

plz post up if you solve the issue ! We will be tackling the issue as it warms up

kgkern01

iTrader: (10)

Well I put an AC Delco opti on it, and it came with the new harness attached. Drove it yesterday, and it seemed to run great, didn't die at all, so it must've either been the Autozone opti, or the opti harness.

Nastyc4, if you haven't ordered a harness yet, I'll sell you the one I just bought, as I wasn't aware the AC Delco one came with a new harness. PM me if interested.

SS#502

Hey guys! I haven't been on here in a long time and came across your issue a couple years ago. Long story short, changed every sensor, opti, wires, couple different sets of plugs O2's all that ****. Anyhow, ended up being the PCM! I mean everything got changed to new, car would warm up and just miss then stall out. If I went to wide open as it stall if would miss and pop and and then go to normal after a couple of seconds. I ordered a new PCM and sent it to Soloman for a tune with all the simple mods done to it. Been running great every since...

myk

iTrader: (4)

People are still tuning for LT1's?