Mike,

Thanks for the idea, I'll look into it. (again) I replaced the IAT sensor early on, (The misfire seemed more pronounced when the ambient air temp was lower)I checked the wiring at the same time and I thought it was all good. Thought the same thing about the TPS,[sm=headbang.gif] until I rechecked it more closely and found a small dead spot in it.
I still have a slight misfire, but as of yet have not had a return of the SES light, and or code(s). I sometimes think it's temp related,(air, not engine) so something in the IAT system would make sense, but sometimes air temp seems to have little or no effect. Still, it's something to revisit.
I'm rechecking for a vacuum leak, as that is something else that would make sense, (given the vacuum gauge fluctuation.) I'm also going to hook up the old leakdown tester as soon as I find it,...( bet it's hiding out with my OTHER fuel pressure gauge![sm=partyparty.gif]) to check for a sticking valve.

Again thanks for the idea.

Gator

 

Wayne,
Are you still fighting the misfire issue you had awhile back?
A nickels worth of free advise,.... The sensor is a hall effect type, it either works or it doesn't. But just for gigglesyou might try cleaning and/or removing the vent screens inside the disributor first.It won't cost you any $$$ and you only have to remove the cap and rotor to access them (there are 2) There is a TSB in effect for it (# 03-06-04-041A) so it's something worth trying .It's like a 5 minute deal. Give it a shot.
Gator
----------------
SorrY for delay,just seen your reponse today!
YUP still fighting my *chitty-chitty-bang-bang* * now that it'sgetting colder,the problem is really showing it's ugly head.Just 2days ago, while coming out of a intersectionthe dam thing gave itself gas and spun me right into the oncoming lane!! good thing nobody was there. i so WISH this issue was a past one,and yes off to the stealership for the umpteenthfrigg'n time. My guess is the computer is fried..

 

Hello-
This is kind of an old thread but just curious to know because I am having almost the exact same problem with my 1998.

Gator: I was just wondering if just adding dielectric grease to the back side of ICM is what most noticably reduced hesitation. What do you think the logic to this is? Is the grease isolating the module?
Did you replace the module again when you added the grease, or was that the fix?
I must say it sounds like a bizarre fix , but you can't argue with results.

Thanks
Kelly

 

The grease does not insulate, but allows for better heat transfer given the gap filling nature of grease. There are more appropriate thermal transfer pastes that can be used, but dielectric grease should suffice.

Without first hearing from Gator, I cannot say for sure whether he replaced it or not, only my take on the situation. If the module was heating up due to poor heat transfer to the bracket/heat sink, this could cause things to not operate properly when hot, but work perfectly fine when cool. I do not believe that he replaced the ICM once he changed the grease, but I could be wrong.

 

Thanks
Sounds like poor placement of a sensitive piece of electronics.
May not be my problem but it sure is interesting.

 

I wouldn't consider it poor placement... The old ones were in the base of the distributor and used the distributor housing as their heat sink... They had many more problems than the newer designs do. But I agree with Gator, the new one should have come with a small tube of thermal paste.

 

Kyle,
Blazeofglory Changed the TPS and the MAP sensors.Tomorrow I will go through all my grounds again, so far all the wiring and electrical componants have checked out fine or have been replaced. Everything I have done up to this point has helped but not cured the problem, ha has also Checked / cleaned and reinstalled all the grounds.guess i'll throw some more money at it tomorrow ( cap, rotor, and plugs) even though I don't think it will make any difference. Plug wires checked out fine (multimeter) and no signs of arcing to ground by sight or sound (checked last night) As for the distributor I inspected it while it was out during the MFI spider upgrade and it appeared to be fine, nothing worn, cracked, broken etc.standard production tolerences (excessive shaft end play, corrected with a moroso shim and a new roll pin) I haven't checked the ignition pick up yethe alsoSpent the morning replacing vaccum lines as some were starting to deteteriorate.Replaced the pick-up in the distributor. he has not checked the timing (with a timing light) becausehe was under the assumption that the computer was responsible for timing and that it was not adjustible.the distributor housing doesn't rotate when the bolt is loosened. That being said I haven't looked to see if there is even a timing tab on the front cover. I'm sure that there is a probe holder for a magnetic pick up type timing light, but all I have is a snap-on inductive style. If there is a timing tab I could check,(if just to rule out any timing issues) I don't believe that it is a timing issue as the miss is during light/ part throttle cruise only.( usuallybetween approx 18-2400? rpm/ 50-65mph)Under idle/ acceleration etc. it doesn't seem to be a factor. In my understanding if it was a timing or valve train event, like a weak spring for example it would start at low rpm and get progressively worse no matter what kind of load was present. I'm still leaning toward an electrical system issue or vaccum leak. Doesn't mean thathe won't check to rule them out


I Hope this is what you were looking for Kyle...

Quinnman105

 

How bad is the stumble? Like barely noticable or pronounced?

 

Its barely noticeable, and is usually only foundif I search for it.(hold in first or second gear at about 3000 rpm) Did most of the typical tune up stuff. Cap, rotor, plugs, wires, PCV, Fuel filter,replaced acouple of rotted vac. lines, cleaned EGR and MAF & fuel pressure test checks out.
Everything I have done has seems to help. I think the MAF sensor cleaning was the most noticeable.
Did it last nite.

MAF sensor was very dirty. Is it possible that the computer will take some time before it will "relearn"
how to run after all these changes. Lets say due to dirty MAF sensor engine is running rich or lean and causing a misfire. After MAF is cleaned, I assume the ECM is still trying to correct for the problem.
Could this take a little while to "relearn" or does this happen very quickly.

 

At this point, I suppose it would be best for quinn and boarder to create separate threads to keep track of the diagnosis on each vehicle... Please post a new thread with your symptoms, what you have tried and/or noticed. That'll help keep down the confusion on my part atleast! LOL