my 1996 88 wont start intermittly

[MrGazoo]

Hi Hope you Guys can help. I Have a 1996 Olds 88 3.8L I start the car drive about 20 minutes to the store shut off the car when i come out 5 minutes later the car cranks but will not fire up. no this happens intermittly i can drive it for 2-3 weeks with no problems then BOOM no good. i let the car sit for 2-3 hours and it starts back up. this is what has been replaced Fuel pump,fuel lines, filter, ECM, Alternator, Powerpacks (all coils) new battery, battery cables. Now when this happens i remove any one spark plug wire do the old fashioned screwdriver in the wire and hold it 1/4 inch away from ground and have my friend crank it and no spark. Now heres the Kick in the pants the old man on the block walked over to me when it happened with a Booster pack and said to jump start it. I said it is not the problem the motor cranks over strong as soon as we hook the booster pack it fires up so now i carry one with me and every time the car cranks and will not fire up i hook up the booster pack and Vroom. What the Heck am i nutz it don't make sence Like i said i replaed the battery, cables, alt. I am lost Please help.

[Mickey#1]

Very very strange, I can see why you're

It sounds like a battery/connection problem.
Did the problem start before or after you replaced the battery?
Did you replace all the battery cables?
Does the car have a voltage gauge?

[MrGazoo]

Hi the problem happened long before i replaced the battery that's why i replaced the battery and cables it's like something is getting a jolt when i hook up the booster pack. another way i get the car started when it happens is when i remove either battery terminal for a minute and hook it back up it starts. remember the car cranks over strong just no spark unless i let it sit about 2 hours or jump it or remove the batt terminal

[Mickey#1]

Did you replace all the battery cables?
Does the car have a voltage gauge?

[MrGazoo]

Yes and Yes

[Mickey#1]

How low does the voltage gauge drop while cranking?
Does the car have a remote starter or any other aftermarket items?

[MrGazoo]

OK i hooked up a digital multi meter to get a accurate reading when the key is on engine off 12.5volts, cranking 11.3volts, and running 13.8volts

[acidcrashdburnd]

goto junk yard get a used PCM from the same year car as your.
Replace.
or just check your wires going to the computer
could be something stupid
had that problem with a 93 GP

[maxwedge]

Originally Posted by MrGazoo

Hi Hope you Guys can help. I Have a 1996 Olds 88 3.8L I start the car drive about 20 minutes to the store shut off the car when i come out 5 minutes later the car cranks but will not fire up. no this happens intermittly i can drive it for 2-3 weeks with no problems then BOOM no good. i let the car sit for 2-3 hours and it starts back up. this is what has been replaced Fuel pump,fuel lines, filter, ECM, Alternator, Powerpacks (all coils) new battery, battery cables. Now when this happens i remove any one spark plug wire do the old fashioned screwdriver in the wire and hold it 1/4 inch away from ground and have my friend crank it and no spark. Now heres the Kick in the pants the old man on the block walked over to me when it happened with a Booster pack and said to jump start it. I said it is not the problem the motor cranks over strong as soon as we hook the booster pack it fires up so now i carry one with me and every time the car cranks and will not fire up i hook up the booster pack and Vroom. What the Heck am i nutz it don't make sence Like i said i replaed the battery, cables, alt. I am lost Please help.

A scanner connected when this happens will display whether the pcm sees cranking rpms when the no start occurs, if no rpms suspect the crank sensor or wiring from the cps to the ign module or ign module.

[Mickey#1]

Acid - He already tried a different PCM.

MrGazoo - Sorry for all the questions but they're important.
Any aftermarket items like an alarm or remote starter?

When I first started reading your post I thought it was going to be the ICM or crank sensor but the starting with the booster pack sent me in another direction. The best clue you gave us was it not sparking.

For spark you need:
12 volts at the pink/black wire going to the ICM.
Good ground at the ICM
A good ICM & coil packs
A good crank sensor
Good wiring between the crank sensor & ICM
Good plugs & wires

The most likely suspects are the crank sensor, ICM & ICM ground. Since you already changed the crank sensor (Don't trust a new part 100%) let's check the ICM ground. Remove the coils, ICM & ICM mounting plate. Note the ground wire underneath the ICM bracket. Clean everything with fine sandpaper or wire brush. Apply some dielectric grease where the ground wire makes contact & anywhere else you think will help prevent corrosion between the ground wire & ICM mounting plate.

It sounds like you never changed the ICM. If you didn't find any significant corrosion on the ICM mounting plate then I would suggest trying a different ICM. You should be able to get one at a junkyard for around $30.