Need Help with ignition troubleshooting
Thread Starter
Instructor
Joined: Dec 2005
Posts: 108
Likes: 0
From: Gainesville Florida
Need Help with ignition troubleshooting
My 92 c4 will crank but not start. The original diagnosis was a faulty optispark which has since been replaced. The coil has also been replaced.
The troubleshooting procedures in the manual say my coil driver could be bad. Would anyone know if this is a likely scenario for a C4 with 96k miles?
The troubleshooting procedures in the manual say my coil driver could be bad. Would anyone know if this is a likely scenario for a C4 with 96k miles?
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
damn... lets get back to basics before you throw anymore parts into this mess.
1) how many miles?
2) What is the maintenance history like?
3) Any diagnostic codes?
Next... some insight.
1) VERY rarely will a failing opti keep an LT1 from starting. I doubt the opti was the cause upfront - it was the most profitable one, tho.
2) Check for air, fuel and spark. If there is a lacking of one of those three, you will have a problem. A very common problem is a chaffed and grounding coil wire. Check that. You make no mention of any diagnostics having been performed on the fuel delivery system.
3) make sure all connections under the hood are secure and clean. A bad connector at the coil driver will cause all sorts of problems. Ask JetJocky93...
Fill in a few of these blanks and I am sure we can help you.
BTW, save yourself a lot of money and grief and get a copy of the Helm Factory Service Manual, www.helminc.com.
1) how many miles?
2) What is the maintenance history like?
3) Any diagnostic codes?
Next... some insight.
1) VERY rarely will a failing opti keep an LT1 from starting. I doubt the opti was the cause upfront - it was the most profitable one, tho.
2) Check for air, fuel and spark. If there is a lacking of one of those three, you will have a problem. A very common problem is a chaffed and grounding coil wire. Check that. You make no mention of any diagnostics having been performed on the fuel delivery system.
3) make sure all connections under the hood are secure and clean. A bad connector at the coil driver will cause all sorts of problems. Ask JetJocky93...
Fill in a few of these blanks and I am sure we can help you.
BTW, save yourself a lot of money and grief and get a copy of the Helm Factory Service Manual, www.helminc.com.
Thread Starter
Instructor
Joined: Dec 2005
Posts: 108
Likes: 0
From: Gainesville Florida
Thanks for your replies, here is the history.
1. The car has 96K miles.
2. I am the original owner, and besides the water pump, this is the first real problem I have had with the car.
3. The diagnostic code is H42 -- which appears to correlate with the no start condition.
4. I had the car towed to the dealer who said the water pump was leaking and that it took out the optispark. They wanted $2k to repair and I said no way. After pulling the water pump, it appeared to be fine. After replacing the optispark with a fresh unit from AC delco (cost $500) the car still will not start.
5. The troubleshooting procedures for error H42 specify using a voltmeter to probe the coil driver harness terminals. The results of the test indicate that the coil driver is receiving voltage from the ECM, which means that the coil driver *could* be the problem.
6. I assume that the distributor is receiving spark from the coil, but honestly I am not sure of a safe way to check the output from the coil to the distributor?
7. In the back of my mind, I wonder if it is a fuel problem, such as water in the gas, but the error code of H42 indicates an ignition problem.
1. The car has 96K miles.
2. I am the original owner, and besides the water pump, this is the first real problem I have had with the car.
3. The diagnostic code is H42 -- which appears to correlate with the no start condition.
4. I had the car towed to the dealer who said the water pump was leaking and that it took out the optispark. They wanted $2k to repair and I said no way. After pulling the water pump, it appeared to be fine. After replacing the optispark with a fresh unit from AC delco (cost $500) the car still will not start.
5. The troubleshooting procedures for error H42 specify using a voltmeter to probe the coil driver harness terminals. The results of the test indicate that the coil driver is receiving voltage from the ECM, which means that the coil driver *could* be the problem.
6. I assume that the distributor is receiving spark from the coil, but honestly I am not sure of a safe way to check the output from the coil to the distributor?
7. In the back of my mind, I wonder if it is a fuel problem, such as water in the gas, but the error code of H42 indicates an ignition problem.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
You can check any one of the wires with an iductive timing light to check for spark.The computer usually does not lie so exhaust the trouble shooting of the ignition before going elsewhere.If it is the ICM make sure you use the heatsink paste when you replace it.
Now has the car ever run since the opti change?If not it is possible to install an early year opti off a couple of teeth and it will not start.It might pop in the intake a couple of times but that is it.Don't ask how I know....
Now has the car ever run since the opti change?If not it is possible to install an early year opti off a couple of teeth and it will not start.It might pop in the intake a couple of times but that is it.Don't ask how I know....
Last edited by Redeasysport; Dec 6, 2005 at 06:26 PM.
Thread Starter
Instructor
Joined: Dec 2005
Posts: 108
Likes: 0
From: Gainesville Florida
I have actually done the opti twice, thinking the remanufactured was not reliable. I am almost certain that the opti is aligned correctly, because of the connecting spindle is notched, and I was carefull to slide it in correctly.
The car did start after the first opti change, but only after turning the engine over repeatedly. It ran perfecly for 5 minutes and then died about 1/2 a mile from my house.
The car did start after the first opti change, but only after turning the engine over repeatedly. It ran perfecly for 5 minutes and then died about 1/2 a mile from my house.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
What about the second one did it ever start?You should have pulled the cap on the first one to check it.You can throw money at it and replace the ICM or you can get the Helm manual and troubleshoot the code the right way.The obvious is check and clean all the wiring and connectors closely.Have you checked your fuel pressure?You know air,fuel ,spark make sure you have them.Check your plug wires for spark with a screwdriver.If none then the coil wire with a timing light.If none either coil or ICM is bad.
My policy is to never use reman or non OEM parts on any thing that is not easy to change.My list includes O2's,Opti,Altenator,Waterpump in that catagory.Some people have had trouble with Reman optis in the past.
My policy is to never use reman or non OEM parts on any thing that is not easy to change.My list includes O2's,Opti,Altenator,Waterpump in that catagory.Some people have had trouble with Reman optis in the past.
Last edited by Redeasysport; Dec 6, 2005 at 09:53 PM.
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Thread Starter
Instructor
Joined: Dec 2005
Posts: 108
Likes: 0
From: Gainesville Florida
Problem is solved. Bad Coil driver. Thanks everyone for their posts especially readysport. As one final note, the actual cost of the repair should have been $75. The actual cost was close to $800 because the chevrolet dealer misdiagnosed it and I was stupid enough to believe them (imagine that).
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Fool me once shame on you fool me twice shame on me.Glad you got her running.I have yet to find any better info on these cars than right here.And we all read the horror stories like yours about the rip off artist out there.Get your Helm manual and run it by this site before taking it to a shop is the best advice available.So they replaced your opti due to a bad driver I would at least go there and give them a piece of my mind and ask how they could misdiagnose your car so badly and ask what they want to do to make you happy.
Thread Starter
Instructor
Joined: Dec 2005
Posts: 108
Likes: 0
From: Gainesville Florida
Actually I replaced my own opti. They wanted to close to $2000 to change the water pump and opti -- which I thought was pure robbery. So I had the car towed back to my house and did the work myself. But as you can see, the opti was never the problem -- it was the coil driver. I don't think they even did a diagnosis. I think they were just taking a wild *** guess and then charged me $90 for their "services".
