Helllllppppp!!!!!!
Thread Starter
6th Gear
Joined: Oct 2020
Posts: 6
Likes: 1
From: Aransas Pass
Helllllppppp!!!!!!
Driving home Friday evening 80 mph on the cruise and she just quit, like you turned the key off. Cranks like crazy and won’t fire. Trying to rule everything thing else out before I pull the trigger on a new opti. Today I replaced the ICM and the fuel pump. Still no fire. 96 LT1 147k. Any ideas or should I just move on to the opti.
Melting Slicks
Joined: Jul 2005
Posts: 2,649
Likes: 863
So - IMHO - 1. Check for spark at the coil output while cranking. If you do have spark at the coil output - check to see if you have spark at a couple of (the easier to get at) Spark Plugs.
2. Do you hear the fuel pump run for a second or so when you first turn the ignition on ??? If so- check for fuel pump pressure at the schrader valve on the fuel manifold. (You should see something like 43 - 45 psi while cranking)
3. Any Check Engine lights ??? (There are two "outputs" from the Opti to the PCM - a High res output and low res output. If either one is missing - the Check Engine light will come on. If both fail at the same time - no check engine light and the car won't run.
3. If you have no spark at the coil output - it's possible you have a Bad Coil - or the Replacement Ignition Control Module is bad (while not common - it's happened). You can see if you are getting any kind of a tach signal when cranking - or you can see if there is some kind of voltage change at the neg side of the coil as you crank.
2. Do you hear the fuel pump run for a second or so when you first turn the ignition on ??? If so- check for fuel pump pressure at the schrader valve on the fuel manifold. (You should see something like 43 - 45 psi while cranking)
3. Any Check Engine lights ??? (There are two "outputs" from the Opti to the PCM - a High res output and low res output. If either one is missing - the Check Engine light will come on. If both fail at the same time - no check engine light and the car won't run.
3. If you have no spark at the coil output - it's possible you have a Bad Coil - or the Replacement Ignition Control Module is bad (while not common - it's happened). You can see if you are getting any kind of a tach signal when cranking - or you can see if there is some kind of voltage change at the neg side of the coil as you crank.
Le Mans Master
Joined: Nov 2006
Posts: 5,032
Likes: 204
From: Greenwood Indiana
2021 C4 of the Year - Modified Finalist
C4 of Year Finalist (appearance mods) 2019
Check these things first, but I feel it's the opti. Get an AC Delco for the replacement. I got mine a $ummit R@cing.
Drifting
Joined: Apr 2020
Posts: 1,925
Likes: 610
From: Orange, CA
Anyway, to OP...
1. As others said, check for codes first. https://tech.corvettecentral.com/201...trouble-codes/
2. Check with a noid light to see if the injectors are firing. Injectors not firing means it's likely opti-related (since the PCM won't command the injectors to fire unless the proper timing signal is received).
3. Your car is OBDII, so an OBDII reader may be able to help you as well.
Best of luck.
Drifting
Joined: Apr 2020
Posts: 1,925
Likes: 610
From: Orange, CA
Anyway, time to move on to step 2. Checking the injectors with a noid light. Injectors firing or not will be a pretty sure-fire way of seeing if your PCM is receiving the timing signal it needs to run.
