MISFIRE AFTER TRANS INSTALL?! SOS

New to the forums so thanks in advance for any help! The story is, last summer my input shaft and pressure plate took a dump on the highway and waited till this summer to finally get it fixed. A few grand later and the trans was back together, but now its got an intermittent misfire that i cant seem to hunt down. Already did plugs, coils, 02s, a/f sensors, cleaned the MAF, TPS, FRPS, changed fuel filter, checked all vacuum lines visually and with starter fluid, did a compression test and leak down test and everything read normal, any other ideas guys?? I'm at a loss here. Also if i turn the car off then on again it seems to "reset" and will be fine for a good few miles, then start to break up again.

Car is an 03 termi with a twin screw on a built motor.

does the car have csts?

clogged exhaust from sitting?

a vacuum Guage will show clogged exhaust..

bad gas..

and has check engine light come on yet?

Could the plugs for the O2’s sensors got put on the wrong sides when the transmission was out? I would think that would throw a CEL though.

hotcobra03 said:

a vacuum Guage will show clogged exhaust..

bad gas..

and has check engine light come on yet?

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Reading full vacuum and boost, exhaust is Kooks LTs to a 3in Kooks O/R X to packs turned down, nothing really to clog lol, have had the exhaust off a few times anyway and its flowing well still, no CEL. It's been almost a thousand miles since it started so can't be bad gas. Already sea foamed it twice anyway though in case.

Rich'sTRsvt said:

Could the plugs for the O2’s sensors got put on the wrong sides when the transmission was out? I would think that would throw a CEL though.

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Thought the same thing, or at least it was something to do with 02s since its the only thing they would have touched, but replaced them with brand new ones myself to no help:/

svt_snake1 said:

Thought the same thing, or at least it was something to do with 02s since its the only thing they would have touched, but replaced them with brand new ones myself to no help:/

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Still might be worth checking to make sure they're plugged into the correct side. I've seen that happen with the S197 guys when doing clutches and stuff. The O2 plugs get reversed and cause all kinds of issues.

slo984now said:

Still might be worth checking to make sure they're plugged into the correct side. I've seen that happen with the S197 guys when doing clutches and stuff. The O2 plugs get reversed and cause all kinds of issues.

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Definetly will take a look, possible they may have gotten crossed on top of the trans somehow? Not sure how the wires run past the harnesses.

svt_snake1 said:

Definetly will take a look, possible they may have gotten crossed on top of the trans somehow? Not sure how the wires run past the harnesses.

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It's possible. Or something could have been pinched when the bellhousing went in.

slo984now said:

It's possible. Or something could have been pinched when the bellhousing went in.

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Will jack it up tomorrow and get a look, fingers crossed

Better get a telescoping mirror and light. It’s freaking tight up there.

Just did and RXT 1200 on my car and I shit you not, getting the O2s plugged back in was the hardest part. Had to use long needle nose and long flat blade.


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explain more on what you are feeling?

1/4 pedal it happens,1/2..ect..

is it a bang noise?pop?

more like a stumble,no reaction to throttle?

MG0h3 said:

Better get a telescoping mirror and light. It’s freaking tight up there.

Just did and RXT 1200 on my car and I shit you not, getting the O2s plugged back in was the hardest part. Had to use long needle nose and long flat blade.


Sent from my iPhone using svtperformance.com

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Yea its guna be a pain to get to in my garage hoping my mirror will reach

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hotcobra03 said:

explain more on what you are feeling?

1/4 pedal it happens,1/2..ect..

is it a bang noise?pop?

more like a stumble,no reaction to throttle?

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Its tough to explain, the car will drive fine for the first few miles after start up before it starts to miss, after its started its pretty constant to about 3/4 throttle before it smooth out a bit, idle is always rough. The misfire itself seems to go through cycles as well, starting off light and gradually getting worse, till eventually it clears up with a "kick."

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Ok so think about things that kick in after it warms up. EGR?

MG0h3 said:

Ok so think about things that kick in after it warms up. EGR?

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Egr is deleted, but if it was something happening only when it warms up I wouldn't think turning the car on and off again would affect it, and the cycling on and off again wouldn't make sense in that case either, maybe ecu? Don't see how that would go bad from sitting though.

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