STEVEN13

Hello,

My 1992 has a miss on the right side bank (as I can hear it popping out the right side tail pipe). Seems to be worse when it gets hot. Some days it runs fine.

I connected a timing light (via spark plug wires) to each cylinder on this bank and I can clearly see on 2 of the cylinders, that they are missing. It leads me to believe that it could be the cap and/or rotor. The opti in the car is from 2004 and is OEM from GM and is not vented (had a Delteq with a vented unit prior to this-Its a long story).

Before I remove the opti to check the cap/rotor I was wondering if anyone has completed a test like this with the timing light and would like to hear your results.

Once I get this fixed I will also post my results.

Thanks in advance!!

Steve

antfarmer2

Any codes? Are the o2's original are the spark plug wires seated good and the icm have heat sink grease on it? How many miles on it?

STEVEN13

Thanks for your response.

No codes, all plug wires are seated good, and the ICM ? The 02 sensors were changed when I installed LT Headers (2008?)

Really looking to see if anyone has used a timing light to prove if the cap/rotor were the issue. If the spark is not consistent on this bank coming out of the distributor-I don't think the other items are the problem.

Regards,
Steve

STEVEN13

TTT

Has anyone tried a timing light to prove if the cap/rotor were the issue.


Steve

antfarmer2

It changes when hot did you use the proper grease when you changed the icm.

STEVEN13

Just wanted to update this thread.

I Re-Checked the spark coming out of the Opti via the timing light and the miss is on both banks (I am sure it always was). When cold most times will run perfect.

When it gets to running temp I swapped out the coil (have a working one). No change. I also have a brand new AC Delco ICM. I changed that when hot and also no change.

Next check will be the spark plug wires-they are 10 year old Tayors.

Regards,
Steve

antfarmer2

When you play with the coil do you use thermal grease on the ICM? And plug wires are always a good idea

STEVEN13

I checked them both separate.

When I checked it with the other coil I just connected it without mounting it. The same with the ICM.

Thanks

cardo0

My bet is the wires are bad. But with 10 year old plug wires arent u due for new wires? Unless the cars been in the garage all the time. A GM Dephi or AC Delco should last nearly 100K mi or more - unless youve got water in it. Well maybe not that good for the early Opti dist but all my opti's that quite would stop all together or stop until cooled off the start again until hot.

Only a few tests u can do to test a plug wire. U can check resistance for an open. They are hi-voltage wires and it would be hard to find an short unless using high voltage test equipment (not available in auto parts stores). Aircraft tool suppliers have something but very expensive and not worth it for $100 or less plug wires. Some owners will wait until dark and spray some water mist over the plug wire then start the engine looking for spark from the wires. Myself i havent done that as u have to be careful u dont shock yourself or get water into the electrical wiring - worst case the opti.

Thanks for sharing, it helps us all.

1993C4LT1

Did you ever figure it out? I'm having the same issue. But I hear it on the driver side

kimmer

I also have the same issue. I used a light on the plug wires to try to chase it down and the one definite thing I found out is its not consistent enough. One time it will show a miss and another it wont.

STEVEN13

I checked it again with the timing light and it seems to be consistent (same cylinders). This time I did it at night-Start engine runs fine cold. Get to operating temp and starts to miss. When I turn off the lights I can see it arcing by the cap and coil. When I rev it up (especially at 1st with most load) it sparked in other areas also.

I have read in the FSM that some glowing (Corona) is normal. But in this case it looks like arcing.

I ordered wires and will update when I install them.

antfarmer2

Do one wire at a time so you get it right the looms can get tricky. On my 94 I loosened my power steering pump and moved it forward to get the wires by. Don't forget the antiziese on the plugs. Have fun with the back pass side and don't cross it.

1993C4LT1

Pretty sure the new wires will help you. I'll have to re-check for arcing in my car.

STEVEN13

I changed the wires and although it runs much better-Its still not fixed. I will swap out the spark plugs this weekend and report my results.

I am guessing that it is the cap/rotor or the opti.

antfarmer2

Did you make sure the wires clicked twice.

1993C4LT1

Keep us updated

STEVEN13

UPDATE:

Installed new plugs and have driven it twice about 35 miles total and no miss or pop! Runs strong to redline.

To recap-I thought a miss/pop on right side bank. Used a timing light on all cylinders and found some were missing on both banks. Noticed some of the wires were arcing and changed them all. Ran better but still was missing. Change the spark plugs and so far runs perfect. If it starts to miss again I will update this thread.

1993C4LT1

Sweet! Let's hope it stays running good

STEVEN13

Thanks! Me Too.