Ignition Coils and Ingnition Control Module

The 3.8 just died in the intersection and rolled into a parking lot and won't start. The code was multiple misfires. P0300.

Shop indicated arcing in the three coil packs and ignition control module. Is this something anyone has experienced. It's about $800 to do the job.

I know where the coils are but not ignition module. Coils shouldn't be hard to replace. Ignition Module, I don't know. Anyone done this?

Corndog...

Ign module is directly under the coils, you should be able to do this yourself, price the parts at Napa or Carquest.

Ign module is directly under the coils, you should be able to do this yourself, price the parts at Napa or Carquest.


Thanks!

I can do that after changing and charging the AC and replacing the waterpump on the damn thing.

Looks to be about 50 bucks per coil and 175 for the control unit. Ist his common? It has about 135K on it.

Corndog....

One or the other but not normally both unless a coil arced over to the module, that would do it.

One or the other but not normally both unless a coil arced over to the module, that would do it.


The shop found all three coils were fried and the control module. I am having it brought home. I will fix it for me for a good daily driver.

I will just go back with the factory parts I guess. Anyone have a good black 1999 LTZ bumper cover for sale?

Corndog....

What will cause this to fail? Age? The car has 135K on it.

Thanks!

Corndog...

I got a new OEM module from this guy for 42.00. It's for a
3.1t but maybe he has one for your ride..
http://stores.ebay.com/MAD-AUTO-PARTS_IGNITION-MODULES_W0QQcolZ4QQdirZ1QQfsubZ2QQftidZ2QQtZkm

I got a new OEM module from this guy for 42.00. It's for a
3.1t but maybe he has one for your ride..
http://stores.ebay.com/MAD-AUTO-PARTS_IGNITION-MODULES_W0QQcolZ4QQdirZ1QQfsubZ2QQftidZ2QQtZkm

Thanks!

I got the module and three coils installed. Unfortunately, that isn't the total problem. It turns over and wont fire. No codes.

I don't want to spend any more than I have on the car. Is a great car but its pretty dead right now.

Any other suggestions?



Corndog...

Thanks!

I can do that after changing and charging the AC and replacing the waterpump on the damn thing.

Looks to be about 50 bucks per coil and 175 for the control unit. Ist his common? It has about 135K on it.

Corndog....

Go to the wrecker first. Then you can swap them out and see before you spend big bucks.

The coils can easily be checked for shorts or open circuit with a voltmeter. They're just coils (transformers) after all, and should all be the same resistance on each pair of connections

Dang too late: sorry: go back and get the old coils there may be nothing nwrong with them

I had the same problem on mine (3.4L v6), and it was the timing belt stripped out.

Needed belt and pulleys (they sell a pulley kit) I think the total was about $350 with belt.

You can do it yourself, but get the overhead cams lined up right and hold them with visegrips.

At this point some real diagnosis is in order, spark at the plugs?, Injectors pulse? will it start spraying carb cleaner into the intake, try disconnecting the maf., Do you see cranking rpms on a scanner?

At this point some real diagnosis is in order, spark at the plugs?, Injectors pulse? will it start spraying carb cleaner into the intake, try disconnecting the maf., Do you see cranking rpms on a scanner?


Will try those things. Yes scanner has cranking RPMS.

Corndog...

Crank sensor?

Back to this beast.

Has spark, compression is 120. Sprayed starting fluid in it. Replaced crank sensor, all three coil packs, ignition control module. So far I have tested the circuits for crankshaft sensor and the camshaft sensor. Still not running.

I am still suspect the timing chain has slipped. Here is the weird thing. With the 3 an 5 plug out to test the spark, the thing started ran for 10 seconds and died.

Corndog. I miss a distributor. Its a lot easier to tell if the chain has slipped. I will pull the wheel off and use a breaker bar to see if I feel any slippage on the crank.

This has me puzzled. This is actually a nice car. Well maintained, new tires.

Corndog...

Check the wire from the cps to the icm for cuts frays and pinches.

Check the wire from the cps to the icm for cuts frays and pinches.

Will do! I paid to have a new oil pan gasket put on the car. Will check on that.
I really want to get this car running. Other than it won't run, I had the wrong bumper cover put on it and that has to be fixed! :-) You dont see many black LTZ's running around.



Corndog...

Here are some numbers I took besides a few continuity checks. I have been using the GM manual to go through step by step.

Power to ICM 11.5v (ICM is new) I think PCM provides power to ICM?

Battery 12.02v (New)

Crankshaft position sensor (Its new) 11.13v Spec showed 6-9v. Maybe I have too much?

I think most of the wiring to make it run is from the crankshaft above to the intake and accross. I was thinking they may have pinch wires when the were replacing the oil pan gasket which they did on a lift and did not remove the engine.

Corndog...

Check the wire from the cps to the icm for cuts frays and pinches.


I didnt see any wiring issues in this area. I did check fuel pressure. Its 44 lbs. I also disconnect MAF sensor tried some starting fluid but nothing. Something odd though. The fuel line going into the back fuel rail is leaking. I don't know how that would cause it not to start. I will remove it and inspect once I figure out how to disconnect it. Probably the O ring.

Still a dead LTZ!

Corndog...

I didnt see any wiring issues in this area. I did check fuel pressure. Its 44 lbs. I also disconnect MAF sensor tried some starting fluid but nothing. Something odd though. The fuel line going into the back fuel rail is leaking. I don't know how that would cause it not to start. I will remove it and inspect once I figure out how to disconnect it. Probably the O ring.

Still a dead LTZ!

Corndog...

Manual reads 48-55 lbs. Surely a 44 lbs reading and also starter fluid wouldn't keep the car from running. It still has a back fire through the intake plenum

Corndog...

I think you need to check valve timing, imo.

Disconnect puter from icm, find out if it starts & runs. This test is for engine basics. If it runs w/o puter connected, you probably have a fried puter circuit.

i would take maf off and and get the cleaner for it. and don't use carb cleaner. they got the cleaner at autozone or advanced or any parts store.

Hey Corndog, My lumina does not like to idle while in drive sitting at a light.
The tach jumps around and it feels like it wants to stall.
It has been doing this every 6 months or so for about 2 years...
Once you are moving along there is not skip
The past 2 weeks the check engine light came on and went off 10 minutes later. The code is a multiple misfire...
This morning while sitting at a light, it was doing it, and I noticed the lights on the dashboard were dimming so I am pretty sure its electrical.
What do you think?
Thanks
Nick

Hey Corndog, My lumina does not like to idle while in drive sitting at a light.
The tach jumps around and it feels like it wants to stall.
It has been doing this every 6 months or so for about 2 years...
Once you are moving along there is not skip
The past 2 weeks the check engine light came on and went off 10 minutes later. The code is a multiple misfire...
This morning while sitting at a light, it was doing it, and I noticed the lights on the dashboard were dimming so I am pretty sure its electrical.
What do you think?
Thanks
Nick

When Mine died I had the multipel misfire. I took it to the shop and they said all three coils and the Ignition control module were fried.

Mine lost power and would barely run. It came to a stop with a big exlosion. TO me. It was timing. I told the shop what happened.

I bought all new GM parts and replaced myself.

The bad thing is I still have a dead LTZ and no clue as to how to fix the thing. This weekend I am planning to take the timing chain cover off because I really think the timing chain is fried.

I have done all the diagnostics and suggestions fro the board I know how to do. I am going with my gut and plan to see the chain and gear all screwed up. If not, I am a t a loss. It will be one of the first things I have never been able to fix. Nice car. Original owner, new Goodyear tires, all leather, black, loaded. all new brakes. its really a pisser!

Corndog....

I have had some time to mess with the car. It does have spark at every cylinder. It seemed to be out of time however. I pulled the cover off and of course the timing chain was fine. Marks line up, good tensioner, now worn teeth. Will clean it up and slap a gasket and seal back on it.

I am pretty satisfied the ignition is working sound. I hated wasting money on the cooil packs, ignition module and crank sensor. I should have just let the shop repair it ans when that didnt work, they would have had to eat it not me.

I will have to focus on the fuel system. I did try spraying carb cleaner and starting fluid in but no start. Just backfire. Fuel pressure is 44 lbs. That may be a little low.

It's a puzzler. I am glad its not a car I need right now. Back to the manual.

Hope everyone had a great Christmas.


Corndog...

Hey Corndog, don't feel bad. I can't figure out why my truck won't start when its cold out. Mechanic said it was the fuel pump so he changed it for $850 and it still won't start. The biggest problem is I need the truck for work. As for your car, that is a puzzler. At least you didn't pay a mechanic to put on all the wrong parts. A backfire kind of seems like an ignition timing problem. You could leave the timing cover off in case valve timing is the problem til you figure it out. I'm pretty sure the car can be started for a second with the timing chain exposed. I worked for a mechanic when I was a kid and when he installed a chain he always check if it would start before buttoning it up.

Hey Corndog, don't feel bad. I can't figure out why my truck won't start when its cold out. Mechanic said it was the fuel pump so he changed it for $850 and it still won't start. The biggest problem is I need the truck for work. As for your car, that is a puzzler. At least you didn't pay a mechanic to put on all the wrong parts. A backfire kind of seems like an ignition timing problem. You could leave the timing cover off in case valve timing is the problem til you figure it out. I'm pretty sure the car can be started for a second with the timing chain exposed. I worked for a mechanic when I was a kid and when he installed a chain he always check if it would start before buttoning it up.

This one has me stumped! I mean the timing marks on the chain are balls on. I did drain the oil because you have to pul the filter off to remove the cover.

I had less than 300 miles on Mobile 1 oil change when the car quit. I found the oil to look a little muddy like it had orange Dexron in it. It didn't look right.

I am wondering if now the intake seals have leaked or a head gasket.

I asked the wife to recant the story. She ran about 65 to 70 miles an hour. No problems. On way home accelerated fine to 65-70 again. As she was driving the car started to slow down and she had not decelerated.

To maintain speed she had to keep it flat on the floor to keep car moving. She started turning off all of the accessories. When she turned into the parking a lot a big plume of black smoke came out of the exhausts and the car shut off. It hasn't started since except when I had two plugs out it fired and ran for ten seconds or so and stopped.

It sure sounds like ignition to me but like I said, three new coils, Ignition module and crankshaft sensor.

Can the camshaft sensor be checked while removed from the car?

I know these cars are famous for intake seal leaks. Is this what folks here report? Coolant in the oil and the car won't run?

Corndog...

Try disconnecting puter from ign. control & starting on just engine basics, (hopefully no diff.). If it starts, problem is in puter. May have fried a circuit. Have come across this prob. @ the shop many times with GM & Toyota vehicles.

Try disconnecting puter from ign. control & starting on just engine basics, (hopefully no diff.). If it starts, problem is in puter. May have fried a circuit. Have come across this prob. @ the shop many times with GM & Toyota vehicles.


Thanks Bear

I actually removed cable from ICM. No luck. I will pull it this weekend and try once more.

Corndog...

Are the plugs new? Wet plugs will shunt all spark energy to ground through the insulator and there will be no joy until they are dried (replaced).

If the plugs are flooded put some oil in the cylinders crank over then install dry spark plugs. Sometimes you will loose compression as the gas removes the oil. If this doesn't work check compression a worn valve spring will cause a backfire. Also Ohm plug wires look for appx. a 1/2 scale reading.
Put the engine at TDC and check if the rotor is at No.1 cylinder.

If the plugs are flooded put some oil in the cylinders crank over then install dry spark plugs. Sometimes you will loose compression as the gas removes the oil. If this doesn't work check compression a worn valve spring will cause a backfire. Also Ohm plug wires look for appx. a 1/2 scale reading.
Put the engine at TDC and check if the rotor is at No.1 cylinder.

Rhandwor and Blue Bowtie,

Thanks! The plugs were junk. I never suspected it but when the ignition module and coils went out I guess the fuel system just flooded those plugs. They were junk.

Its been a while since I have had time to mess with the LTZ. After thinking I had timing problems and pulling the cover. I spent yesterday putting it back together. I have a leak on one of those plastic fittings. I replaced but one is leaking.

As far as the car, it is running. I do have a code on the number 6 cylinder. I did mess up a couple of spark plug wires getting them off. I also hear a very loud ticking around the alternator. I dropped the ting hard. I hope thats what it is. I will pull off the belt and see if it goes away. On start up, the white smoke poured out of this thing. Going to address the plug wires and see about number 6.

I shut it down after the ticking. I didn't want to mess anything else up.

Anyway, it's good to hear it run again.

Thanks for everyone's help.

Corndog...