stupid stubmle

[JayLashua]

My sick car, in open, then closed loop modes

I just changed from Bosch Platinum plugs to AC R43TS and did an oil change as well. I changed the plugs in hopes to eliminate a weird stumble, but i still have it..

Jim Testa told me it may be a coil pack because its more difficult to fire on a weak spark when its lean, but would fire fine if it was running rich (or open loop)


I'm not sure what it is though, last year with the previous engine, it was perfect.. and in the time between, the coil/module was just resting in my trunk

help majorly appreciated!
Oh yea, i have MSD Super conductor wires... i know people have bad luck with magnecores, but who knows how these are too..

 

[Turtle TR]

HOLY CRAP!

That's exactly how my car is sounding. I first thought it was the MAF. I did that tap test, no change. Pulled the plug out and the car idled smooth. swapped that out but I still had the same problems. My Dad said that the timing is off and that the timing chain had to be changed. I ordered the new chain and a new cam sensor. Better I change them now or be hindered later. So I'm just waiting on parts. The way you described the coil pack hindering the car is worth looking into. I'm going to change mines out also.

 

[JasonB]

I will probably be no help to you but, here is what happened to me. I did the ECM swap to the 87 ECM and I had what sounds similar, I couldn't even drive the car with out it stumbling and back firing past 1/4 throttle but I was getting codes 42 33 and 44. Codes 33 and 44 are mass air and 42 is electronic spark timing failure. Turns out the remanufacture by GM ECM I got was a remanufactured piece of junk.Got an ECM from the junk yard and its ok, no more stumble. Like I said I dont know if any of this will help but my car sounded exactly the same as yours.

 

[JayLashua]

I dont know what happened but i remember submitting a reply to thi slast night.. anyhow

it turned out to berunning on 5 cyls, the #2 wasnt plugged in completely, anyhow, still does the stumble though.

I had tried using a caspers coil tester, and it doesnt fit the damn thing...

next thing i was going to try it a 1987 coil on it...would like to know if anyone else has tried this and if it will be compatable.