: Northstar missing at idle

Dave F.
08-09-04, 07:47 PM
Please help, I have a 1997 Deville and just recently replace engine because my old northstar had blown head gasket and was overheating. I was advised by my local cadillac dealer to find a good used northstar and install, which I did. I found a engine with 80000 miles on it. After replacing engine, it started right up and sounds good. But my problem is that when you come to a stop when idling the check engine light comes on and it starts missing and when you accelerate it clears up. When checked with scanner it always showes that cyl. 2,4,6,8 are misfiring. Checked plugs, wires, all check out good. What could be causing this problem that is isolated only to the front cyl. Please help, this problem is about to cause me to pull my hair out...
When your on highway engine seems to run good, does not turn on check engine light, only at idle.


08-09-04, 08:16 PM
Are you sure your spark plugs and wires are good? I had the same problem, and changed my plugs and wires, and problem was solved. You are showing a misfire on one complete bank of cylinders. Did you change wires and plugs when you changed your engine? That was the time to do it. I hope you didn't use the same components from the old engine.

The fact that you have smooth operation at any speed other than idle should point you to check all of your igntion components. Make sure your wires are plugged in at the coil, and it is possible that the wire connectors inside near the plugs could be firing straight to ground and causing the misfire. The check engine light is on because of the misfire. Injectors are another source of trouble.

If all of that is okay. maybe your engine is really bad.

Keep in touch! Hope you have success with your car.

08-09-04, 08:18 PM
duplicate post

08-09-04, 08:20 PM
Sorry for the duplicate posts everyone. If I knew how to delete them, I would.

08-09-04, 11:31 PM
I'd bet plug wires. They can cross talk, fire to ground.

08-10-04, 08:57 AM
I would double check the plugs and wires again also. When I first got my Eldy, I was checking the plugs that were already in there. They didn't seem too bad, but I could tell they were in there for a while. So, I put the plugs back in the engine and figured I would drive up to the parts store to get some new ones. All of sudden, as soon as I started the car, I was misfiring. Got some new plugs, installed them, and then it was all straight.

There are some parts that I always replace and maintenance that I do when I get a used car; plugs, wires, air filter, oil change, fuel filter, pcv valve. Also distrib cap and coil on older vehichles. It is good peace of mind (is that how that phrase is written?) to know that you installed new parts on your vehichle. Then when you do have a problem, you aren't wondering how old a part is and its reliability. I bargain the estimated cost of maintenance into the price I will pay for the car.