1G Weird Misfire/popping

[scott90gsx420]

Ok so i have had what seems like a misfire for a while. Issue started months back and hasn't got worse but hasn't got better. The car will misfire/pop especially at idle. When it does this the W/B goes a bit lean then is good again until it misfires again.

There is no CEL and I noticed it doing this right after me and my brother were out tuning the car a few months back. It was running fine we did some tuning and when i got back there were two issues one being this misfire and the other being that my alternator was wobbling around inside the casing (Like you could see stuff inside it wobbling back and forth.) I replaced the ALT but the misfire issue is still there.

The issue happens mostly when idling but does happen when cruising at low RPM's and when decelerating. In boost its just fine and the car doesn't seem to do it while cruising (Unless below like 1500rpms).

It DOES NOT do it during initial warm up but after the cars warmed up a bit it starts doing it.
It also DOESN"T always do it. For example I'll come to a stop and it will idle fine for 10 seconds or so then it will start popping.
And it isn't consistent so it will pop/misfire then wont do it for a few seconds then does it for a few compression cycles then doesnt do it again.

I've replaced the intake manifold gasket twice and the last time replaced the TB gaskets. The first time it seemed like it was fixed but then after driving to boise it was misfiring again. Oh and I replaced plugs less then 2000 miles ago and my wires are about a year old..

BTW one bolt is stripped on the intake manifold its not around the runners but its the one that is on the far left of the motor when looking at it from the front. It doesn't seem like it would leak right there but IDK, i'm stumped.

SORRY THIS IS SO LONG GENTS IM JUST TIRED OF THIS ISSUE AND FIGUERED IF I SHED LIGHT ON everything MY CHANCES OF RESOLVING THIS WOULD BE BETTER..

Any help is much appreciated thanks guys,

 

[doubleclutch99]

Check the gap on the plugs and look the wires over. that would be a good place to start. just a thought

 

[95dsmgsx95]

Sounds like its running rich which is causing it to back fire. Maybe you need to re-tune.

 

[scott90gsx420]

I replaced the plugs gapped to .028. And The wires are only like 4-5 months old. I thought maby i was rich to as its been starting to get warm hear but i leaned it out and she still does it. Im kinda thinking the coil pack but i don't wanna start buying parts unless thats what it is. What do you guys think?

 

[scott90gsx420]

Still having this issue i edited the OP so that it was more descriptive also thanks again..

 

[scott90gsx420]

Well guys i think i solved my issue.

MONTHS (like 6 or more) back i did the blue wire mod with my safc so i could read my o2 voltage. I knew it was a bad idea but needed another tuning tool besides just my egt gauge so i could get the car running right.

I never used it after probably the first day as i bought a WB shortly after. Well i pulled the ecu to see if it was bad (Which it looks MINT haha i was way impressed also found out that it had caps changed in May 2003) and as i was putting the ECU back in i seen the blue wire.. Cut the wire off and put her back together and took her for a ride..

So far the problem seems like its gone. The car honestly just sounded better/smoother afterwords haha.

Let her warm up to where it normally would start doing it and the car never went into closed loop.. Shut her off, reset the ecu, and turned the settings WAY down. Got her cycling which is where it was misfiring and it didnt do it. Granted i only went for a small drive but before it would have started misfiring before in that time..

So 90% sure the issue is gone leaving in 5 for a longer drive will post EXACT results later.

 

[AllenTallen]

Well guys i think i solved my issue.. MONTHS(like 6 or more) back i did the blue wire mod with my safc so i could read my o2 voltage..I knew it was a bad idea but needed another tuning tool besides just my egt gauge so i could get the car running right..

I never used it after probably the first day as i bought a WB shortly after.. Well i pulled the ecu to see if it was bad(Which it looks MINT haha i was way impressed also found out that it had caps changed in may2003)and as i was putting the ECU back in i seen the blue wire.. Cut the wire off and put her back together and took her for a ride..

SO far the problem seems like its gone.. The car honestly just sounded better/smoother afterwords haha.

Let her warm up to where it normally would start doing it and the car never went into closed loop.. Shut her off reset the ecu and turned the settings WAY down.. Got her cycling which is where it was misfiring and it didnt do it.. Granted i only went for a small drive but before it would have started misfiring before in that time..

So 90% sure the issue is gone leaving in 5 for a longer drive will post EXACT results later..

Sorry to bring up such a old post but I’m having the same exact issue you were having and can’t seem to find the problem. Identical issue to yours. Did you resold this issue 100%? Thank you!