Hit and a miss? missing, shuddering problem

[shantel_3]

Hi guys, i am having a missing/ shuddering problem with my car. I havent been able to build a boost leak tester yet, and i was wondering if you guys could look at the symptoms and tell me if it sounds like a leak problem (i dont think it is a leak). This all started about a week ago, and came on instantly. the weather was a little colder that week (-15 C), and i dont think it had been driven very much. Im thinking if its not a leak, maybe its a bad TPS or spark plugs, or an injector maybe. I would like ideas about what else it could be, other than a leak.


symptoms (engine temp normal):

-during idle it will ocasionally miss

-it will drive fine at about until about 1/2 full throttle, and then a sudden loss of power and shuddering will occur. If I let it go back to a low throttle position it goes back to normal.

-it can build up to 8 or even 10 psi of boost with low flow rates (under 1/2 throttle - this is why i dont thinks its a leak)

- it doesnt seem to happen/ correspond to any boost level, rpm level, speed, etc.

let me know what you think. thanks

 

[m1nd64m3]

My car ran the same way when I first bought it and it turned out to be the spark plug wires were bad. But I would build the boost leak tester first, and if thats not it then replace spark plugs and inspect or replace the spark plug wires as well. Also test the coil pack.

 

[shantel_3]

how would i go about testing the coil pack? (is it on vfaq or something?)

 

[m1nd64m3]

http://www.dsmtuners.com/forums/showthread.php?t=2303&highlight=procedure+for+testing+coil

Scroll to the bottom of the thread, the testing procedures are in there.

 

[shantel_3]

cool, thanks.

other ideas would still apreciated...

 

[shantel_3]

I did a compression test the other day. It was 120 across the cylinders (within 2-3 psi). This makes me think its not an internal problem (although that is low...). didnt do a wet test, however.

 

[ddavisaf]

Your symptoms sound like a boost leak. Another thing though, it to make sure you have NGK BPR 6ES spark plugs in the car gapped at .028".
Stumbling under boost conditions is usually caused by either a boost leak or a bad/weak ignition system.
So that would tell us you've got a problem with either your plugs, wires, coil pack, transister pack (under the coil pack), or a boost leak. Test all of these components and get back to us with what you find.

 

[LinuxWarDriver]

My car is doing the same thing...I have a 92 Talon non-turbo with the 2.0. My car starts to stumbe around 4k. I think I've got it narrowed to the tps. I got a cheap used one on the way from eBay. It cost about 12 bucks and not the 100+ that Advanced Auto Parts wanted. If you have a multimeter you can find instructions on how to test your TPS here.

http://www.geocities.com/motorcity/downs/7678/dsmtests.html

I think you can also find it on the VFAQ and in a shilton/haynes book.

But yes, check your wires and ICS. (any anything else that is painless to check under there)

my 2 cents.




-eBay my little way of sticking it to the man-

 

[shantel_3]

tested the coil today. there was 1.1-1.0 ohms across the coil primary, and about 11000 ohms across the coil secondary. is that high for the primary? specs say max is 0.75 - 0.86 (or 0.95 for 91's). im looking for alligator clips, or something to test the transistor pack right now

 

[shantel_3]

fixed the problem with new plugs and wires. thanks guys