1995 Z28 convertible no mods 80,000 fun miles

The problem first occurred 2 months ago as I approached an intersection at 10mph. The red light turned green and I touched
the accelerator. The motor stopped running at that moment. All electronics appeared OK. I coasted to the shoulder and trying
restarting it. The starter motor cranked normally but the motor didn't appear to make any attempt to fire. After a few tries,
the motor started and acted as though nothing had happened. I drove the car for 2 hours and then shut off the engine for 5
minutes. It wouldn't restart. Several tries and 5 minutes later it started OK and again I drove it for a few hours without shutting off the engine and without problems. This happend several more times over the next few days.

It once happened in front of a garage. We pushed the car into the shop and the mechanic said he found:
. power reaching the coil
. power not reaching plug#1
. the coil wire was corroded.
He cleaned the coil wire connector and the problem appeared to be fixed.

The next day the problem re-appeared so the mechanic replaced the coil.

2 weeks later the problem reappeared. It happened 6 times over the distance of 2 miles at speeds between 0 and 30 mph.

Sometimes it happened when I was casually accelerating and other times when I was at constant speed. The duration of time
between failure and when the motor would restart varied from immediate to 5 minutes. (Crank it for 5 seconds wait for 30
seconds... )

The problem occurred the following morning while driving to the dealer. It stalled and then started within a few attempts. It performed OK at the dealership and they couldn't find anything wrong. No engine codes were getting set.

It ran OK for 2 weeks without incident.

It refused to start for 3 days this week. Several attempts were made on each day to start the car. The car was towed to a garage. Of course once there it started OK. And once again, the mechanic can't find anything wrong.

Other Symptoms:
Sometimes during these episodes after the motor has quit, if I leave the ignition in the ON position the gauages
(spedo/tach/volts etc) all move wildly for 1 second and then are normal.

No engine codes are getting triggered.

Engine sputters shiffing into 2nd when I put my my foot to the floor. It sputters and will not shift unless I ease off on the
throttle. The sputtering is slightly improved since the new coil was installed but is still bad.


1995 Z28 convertible no mods 80000 miles

 

Change all your plug wires including the coil wire.

I would recommend Taylor or MSD wires.

 

It seems like you may have a bad opti.

 

Why would bad wires give me an all or nothing situation. The motor refuses to start at all but once it does, it runs fine.

How can I determine if it's the Opti? Other than buying a new one and replacing it? Other than replacing everything else first?

 

I agree, I would start by replacing the wires. Mine was doing something similar, and the coil wire itself was bad, cleaning the connection only slightly helped.

Anyone ... can you just buy the coil wire?

 

I bought just a coil wire from the dealership.... for $18! (Hey, I need it THAT day, Saturday too). OK I got ripped. Answer: Yes, you can.

I think this is your Ignition Control Module. My car did the same thing, but with an aftermarket ignition box. The ICM was the problem. It sits right next to the coil on the same bracket. If the ICM doesn't fix your problem, replace your optispark.

JR

 

May be the ignition control module that is mounted with the coil. If there is a crack in it or a marginal circuit trace inside, heat can cause it to act up. Same kind of thing can happen with the opti also.

 

agreed. same exact thing happened. Replace the ICM and coil.

 

Open your hood at night and look for blue sparks on the wires or at the plugs.

 

I would suspect 2 things , ign module and or fuel pump, check your fuel pressure and take it for a drive with the fp gauge taped to the wind sheild see how the pressure does. they have testors for the ign modules at most dealerships.

 

ECT the thing on the coil gave me the same problem, and ECM also did the samthing. Are you sure you have no codes did you scan? Is there ever a time it might not be the OPTI ? Fuel pump/filter...

 

It's been scanned a couple of times - by the dealer and also this week by the current mechanic - and nothing found.

The mechanic checked the fuel line today and said the pressure was good between the pump and engine - indicating no partial blockages.

 

yea i was going to say i doubt it was a fuel pump b/c it shouldnt die once its starts...when my fuel pump was going...the car would take to times to start and they when it turned over, it would run fine...it was the starting part that was the PITA...

thank god that was fixed

good luck!

 

Im a dealership tech. (pont). I think you have a spark problem, but dont think its the ICM. it sounds more like the harness that runs to it. or poss. to the PCM. to check for this, w/the eng. running, grab the harness near the conn.s for the ICM and PCM and wiggle them. slightly tug on them in all directions. if thats the problem, you should find it this way. its also poss. that the coil wire is arcing. if you have the orig. plug wires on there still, then its time to replace the set anways. its called, "preventive maintenance". that means you replace certain things cause its not worth it to wait till those things go completely bad. like the plugs, wires, serp. belt, fuel filter, and coolant, and so on. anyways, check the eng. grounds and power wires at the fuse box and near the batt. under hood.


does you car act up mostly when cold, hot, or when? always while on the gas, or has it happened at idle too? Id check all wires for looseness, then look at the conn.s for corosion. also check the crank position sens conn. and harness.

good luck.

chris

 

What did you end up finding out? My car is doing the same thing but shutting off at exactly 180* every time. I believe it is my ect sensor and am going to replace it and see what happens. Since the ect controls spark voltage I think the sensor is bad and not getting enough voltage for a good spark when the engine heats and not enough voltage for when the engine trys to start again.