intermittant cylinder #3 missfire... very wierd please look and help!!

[myblack98gst]

my car is a 98 GST with a complete 6-bolt.

When I am driving along just cruising it will just start with a bad miss and will not stop until either
A) I let off the gas and decelerate for awhile or
B) turn the engine off and restart

Either way i will get about 1/8 -1/4 mile down the road and it will happen again. It quit one time for 2-3 days and drove great, and them sometimes it will start as soon as I pull out of my driveway. Also when it is doing this, when I turn it off and turn it back on it will ALWAYS start missing if I try to go past 3k rpms. The logger shows it to be #3 missfire, in attempt to fix I have done:

1) new NGK BPR7ES plugs gapped .028
2) new MSD 8.5mm wires
3) 2 different coil packs
4) check the injectors for cloggage
5) new fuel filter

I am very seriously considering that it could be the computer itself due to the fact I can turn it off and right back on while driving and it quits?!

ANY help would be greatly appreciated.

 

[myblack98gst]

*bump*

It is still having the same problem. I have checked the wiring mae sure nothing is grounded out. I have replaced the computer and it still does it. What I have found to work the best is to reset the CEL and then restart the car the will make it stop sometimes for a few day sometimes a few hours. I just find it VERY odd that clearing the CEL will make it quit?

the only codes that show are for the emmisions system (removed) and p300 or p303 (it varies between random and #3 missfire)


any help is appreciated.

 

[Eclipsemblue]

Damn clyinder #3, i had the same problem at one point but i fixed it by putting a MSD wire that goes to the coil pack, new spark wires, coil pack.

Um but that doesnt sound like it may work for you... hmmm id try to reset your IAC, on your throttle body, im a 420a engine so im not exactly sure wtf is going on with your engine .

 

[u6t9]

welcome to the world of the misfires....you said you have a 2G with a six bolt? well, so do I and I've got the exact same problem. so does everyone that has a 6bolt in a 2nd gen. it really sucks ass... it has something to do with your CAS. mine worked fine for 2 days and now i cant even drive one friggin' mile without it doing misfiring and sputtering. the only fix that i've run into so far is either shell out the cash for a dsmlink or go here http://magnusmotorsports.com/1g2g.asp and read at the bottom of the page.

hope some of this helps. any questions lemme know

 

[myblack98gst]

I know about the missfire problem with the swap, BUT I thought it was just a small spudder and throw a light. So if it is full out engine miss as if you pulled a plug wire out then okay I will to the pentometer fix.

 

[Tevenor]

Some people get a slight shudder and no light, others get a light but nothing else, some have the engine drop 2 cylinders on you. Depends on the car, the CAS, and the tension of the belt.

The Pot mod is useable but just as dangerous as it is helpful. Some have had good luck by unplugging the TPS, but again not perfect. The best solution right now is to run DSMLink to eliminate the chances of misfire.

And on a side note, I drove mine for a year with no CEL or misfire. Only one I ever got was when I swapped out my 96 ECU and threw in a 95 for the DSMLink. Once I unchecked the misfire DTC, ran perfect once again.

 

[u6t9]

i know i've read posts on here where people say that the pot. fix ruins their engines, i personaly just went outside and unpluged my tps and i'm going to drive around for awhile and see if that did anything....i'll let you know how it works for me.

 

[Carter97GSX]

I'm going to post this here cause my problem sounds similar, but the cause appears to be different. I'm not running a six bolt, and the engine threw a CEL and started misfiring badly after I did a clutch job on my car.

The problem is intermittent in that the light will come on, and it will misfire for a couple of minutes, and then it will stop misfiring, and the light will go out after a day or two, but then it will happen again. I don't know where to start really. The code is P300 "Multiple Cylinder Misfire" but I can't think of a cause which would make this happen so sporadically.

Could it be the coils?

Why would this happen immediately after doing the clutch?

Did I forget to put a wire back or something?

Any help would be greatly appreciated. I don't want to start blindly buying parts for the car without knowing what the problem is. Thanks.

 

[turbo tim1]

I have the same problem, but I narrowed it down to the injector signal pulse.
While the car is idling I rev it up to about 1500 and maintain, the miss fire will begin.
I pulled injector plugs off one at a time and found cylinder 2 made no difference, I stuck a noid light on the injector plug and found no pulse signal until I let the engine come to an idle.
What causes this? I did a 6 bolt swap 4 months ago and this problem just shows up out of the blue.
The car is a 97 tsi 6 bolt swap with C.A.S conversion.