Miss = Bad Coil???

[Wess]

I've noticed this twice now in the last two weeks:

I start the car in the morning and let it idle in park. While idling, I feel a discrete shudder and notice an audible, low level "thud" type noise that accompanies the shudder. Again, very discrete. I shut the car off, turn it on again and everything is fine, no shudder, no noise. I hooked up my handy XC2 to see if there were any codes and pulled nothing.

So I have some questions:

-Is this one of coil-on-plugs going bad?
-If so, will it throw a code?
-Will I see a code only when there is a complete failure of a coil?
-How can I test my coils, or get them tested? (assuming this can be done w/out disassembly of the intake)
-Where is the best place for new coils?
-I've noticed this only recently, since I went with Doug's program and the XC2, do you think there is a correlation?
-Am I barking up the wrong tree?

Thanks in advance!

 

[lndshark]

Could be a coil going bad, dont know why it would clear up on restart though. If you let it run, will it smooth itself out eventually?

Ive read that it will only throw a code when it gets really bad. One guy said he had to rod the heck out of his car for several minutes before he could get his car to throw a code.

THe way to test the front coils is to disconnect the wiring harness one at at time. If there is no change in the way the engine runs, the coil is bad. Makes sense if you disconnect a good coil, the engine will definately let you know.

Muarrys online seems to be the general consensus on where to get coils. Seems Ive heard around 70 bucks. DONT, do what I did, which was walk into a local NAPA, have them get me one, and pay 140 bucks. I was desperate.

As far as the Xcal 2 link, who knows. Havent heard of anyone with similar problems as of yet. Might want to shoot Doug and email.

Good luck,

take care

brian

 

[Wess]

Could be a coil going bad, dont know why it would clear up on restart though. If you let it run, will it smooth itself out eventually?

Good question. I haven't let it run long enough to see if it clears up. I don't know why it clears after a restart either. That's what has me scratching my head.

 

[DavidT]

I have a similar symptom, only on cold starts. I too am using Doug's programming. XCal...
Somebody else had a thread mentioning this, and come to find out, Doug told him that this was normal.
Once the car warms up, it should not have a miss/studder anymore...

 

[ornery1]

yes since dougs program mine does this too

 

[spragers]

Ditto. I started my car the other day, then realized I left something in the house. When I came back I could hear (especially with my louder exhaust) a kind of "thump" or "thud" sound while the car was idling. You could tell the RPM's were bouncing a bit. After I got out driving and gave it some gas it seemed fine. I've also noticed that, since getting the XCal tuing from Doug, the car has run better the longer it runs.

Glad to know this is "normal"

 

[Fourcats]

Ignition prob...

We had a "miss" in the '89...The dealer had a $1500+ est {for bad injectors}. With help from Mike {shopartsnw} that is no longer a problem. In addition to having the problem solved{new plug wires }, we found a great, knowledgeable SHO person {with a wife who races}.
THANK YOU MIKE!

I just spoke to the S/M at the dealer and he is refunding the total amount for the "diagnosis"...So it worked out OK. The bad part is if I had not been there the G/F would have paid the $$$$... :cry: