Idle insanity

[fernleybjk]

I have an intermittent idle problem. The problem occurs when the engine turns over. It either idles perfectly or gives a rough idle but only on initial start-up.

I have it in a repair shop now, NAPA repair center. They have had it for a week and a half and have done nothing to fix the problem. I went in with a rough idle and a cylinder 7 misfire code; they told me that all I needed was a tune-up so I OKed that. Later on they told me that the misfire was caused by something else. They stated that the misfire was caused because two wires leading to the coil shorted together. They proceeded to cut away the coil pack harness and splice the leads. The problem still remained. They told me then that the problem was further down the harness and that they repaired that damage. They stated problem fixed and I can pick up the car. I start a cold engine and immediately the idle problem is back.

I pick up the car yesterday. I start it up and the idle is very smooth. I make 3 stops and the third time I start it, the idle problem is back.

I return the car and tell them that the problem is not in the harness but something to do with the initial start-up sequence. I told them that is why you call and tell me that the problem is repaired but when I pick it up and start it, the problem returns. Once it's running smoothly, the car does not develop the problem.

They tell me that it is caused by vibration. I told them that if it is vibration then all you have to do is move the harness until you create or fix the problem and that would prove the harness. The tech told me that he did that and couldn't find any place that it affects the idle. Then they tried to tell me that it is a heat related problem. I told them if that were true then explain why the car immediately went into the idle fault when I started it up after the car sat for two days.

I tried to suggest all of the things that could cause that from the posts on this site but they tell me that if it were any sensor it wouldn't cause a misfire on cylinder 7 alone but would affect an entire coil pack.

I did read something funny on one of the posts. It stated that you should diagnose the problem and repair based from a solid analysis. It stated not to guess and throw things at the problem or at least make sure the things thrown are in the right direction.

Oh, it is a 98 Mark VIII, Pearlescent.

 

[whiplash15]

Gosh, its sad to read another "repair shop woes" thread. At at least it isnt a FLM dealer thread. Just a couple of guesses on my part here. You have a fairly well maintained 98 MarkVII with 60K + miles, driven mostly in town. This problem has been occassionally, but is growing more frequent. When It does malfunction, the miss continues even up off of idle. Am I on the right track here?
Please do the folloowing, you dont have to be very mechanical. On the drivers side of the engine, remove the coil cover. If I remember, its four nuts. On the third coil back, grab the connector and disconnect it. Using your finger tips, wiggle the third coil a bit as you pull it up and take out. the long rubber tube is an insulator. Five'l get ya ten, the insulator is minutely cracked and on occasion it fires to ground instead of the plug. There is likely no rhyme or reason to the malfunction, it just happens. Now, those insulators are available separately, and you need to call around to find one. They cost less than $5. While you are at the parts store, get a small tube of "Dialectric grease".
Go back to your car, put a generous amout of dialectric grease on each end of the metal spring and reassemble the coil. and reinstall it. Just stop there and start the car.
If the miss isnt fixed, most parts stores will read the codes free. If there is a new code go to that plug and do the same thing to that one that you just did to #7. This is a very common problem and will really bite anyone who has to depend on a mechanic to have it fixed.
I dont mean to be condescending, but I dont know the abilities you possess.

 

[budpytko]

I have an intermittent idle problem. The problem occurs when the engine turns over. It either idles perfectly or gives a rough idle but only on initial start-up.

I

I tried to suggest all of the things that could cause that from the posts on this site but they tell me that if it were any sensor it wouldn't cause a misfire on cylinder 7 alone but would affect an "entire coil pack".



Oh, it is a 98 Mark VIII, Pearlescent.

Duh!!!! Cylinder 7 (as well as all the others) have THEIR OWN COIL !! Hence the term coil on plug!

 

[anoble1_MarkVIII]

I would check the IAC

I would check the IAC

The IAC (idle air control) valve might also be the culprit. Sometimes carbon gets stuck in the valve rendering it problematic and a rough idle. I had three instances of this happening to my '97 before replacing the entire valve. The car has run smooth since then.

 

[steve]

The IAC (idle air control) valve might also be the culprit. Sometimes carbon gets stuck in the valve rendering it problematic and a rough idle. I had three instances of this happening to my '97 before replacing the entire valve. The car has run smooth since then.

I mentioned that in he last thread he had. Not sure if they checked it out.

 

[whiplash15]

After rereading your first post all of the way through, here is some additional food for thought. If in fact they did move the coil to a different position, thay may well have moved the problem also, and unless you read the codes right then you would never know it. It would still miss intermittantly, just like it did before! Also, to prevent further confusion, the mechanis is NOT taking the "valve cover" off, he is taking the "coil cover" off. There is a whale of a lot of difference.
Please if you yourself cannot perform the steps outlined in my previous post in this thread, take it to SOMEONE ELSE and have them do the specific steps that I outlined. It would probably be best to read the codes before you start because now you dont have any idea there the leaking insulator is. Reading the codes will tell you which cylinder is missing. Thats the one you want to fix.

What a fiasco!

 

[whiplash15]

As an after thought, if whomever else you take it to can follow directions, have them repair any bare wires in the loom and LEAVE THE REST OF IT ALONE!! You may be able to tell that I'm totally frustrated by the lack of competence you are having to deal with. I guess there is no excuse for STUPID!

By the way, the IAC is also a possible cause as stated in some previous posts, and if what I outlined doesnt fix the malfunction we can change that next. But lets do the simple and cheap thing first.

I dont know any way I can reassure you that what I am telling you is correct but I can sure tell you that one plug misfiring, sure makes a Mark VIII run like poop.

 

[steve]

If the OP lets us know where he is located maybe someone here can look at it for him or we can get him to a good person.

...
Please if you yourself cannot perform the steps outlined in my previous post in this thread, take it to SOMEONE ELSE and have them do the specific steps that I outlined. ...

 

[fernleybjk]

location - Fernley, Nevada

location - Fernley, Nevada

I am located in Fernley, Nevada, 30 miles east of Reno. I can replace the insulator and put dialectric grease on the ends of the spring myself. I will do that tomorrow morning.

I told them everything that people have suggested but they are so convinced that it is in the harness, they are not listening. They say that if those sensors mentioned like the camshaft sensor or the IAC are bad, they will affect more than a single cylinder misfire.

I truly appreciate all of your help more than I can possibly say. I would be at the total mercy of any repair shop without your valuable help.

thank you, thank you, thank you!

I have my own code reader now and am so POed that I will do whatever I can on my own. The sales manager told me yesterday that they are doing everything they can to assist me but it sat in the parking lot all day without being looked at. He also mentioned that another code has appeared. I feel like I need to get it out of their damned hands while I still have a car left. Should I clear the codes before replacing the insulator?

Yes, the car is always maintained and garaged. I love this car; it is the best car I've ever owned or want to own.

 

[steve]

As long as you documented the codes then you can clear them and try your fix. Then see what if any codes come back.