Cylinder 1 misfire after pi swap.

[tomustang]

after the swap the car runs great, it's got alot more power on the upper end. i took it to autozone today and they pulled the the code for cyl 1 misfire. i've checked the wires and the plug. it's all good. i'm leaning tward the the fuel injector. i don't know. any ideas?

 

[RysRed96GT]

i think if its a bad injector, you'll eventually get a lean code. i had a leak in my intake manifold before and it took 2 weeks for it to finally realize it was lean

 

[tomustang]

i did the swap over a month ago. the electrical is fine. i guess i had the code since then. like i said it runs like a champ though. i had it pulled from autozone, i think it read lean too. i'm gonna go back over and see how much a single injector is.

 

[tomustang]

well, 62 bucks for a injector. before i spend $ on this is there another possible reason why this is comming up as a misfire?

 

[mogs01gt]

What are your plugs gapped at?

 

[tomustang]

stock .055inch

 

[mogs01gt]

stock .055inch

Theres your problem right there. That is way too much. You are flowing more air in there and it would be wise to use a smaller gap. Depending how modified your car is, I would have it between 36-42.

 

[tomustang]

they're .055 all around but just 1 cylinder is bad, how would that be? before exhaust i got PI heads and a ported intake

 

[mogs01gt]

they're .055 all around but just 1 cylinder is bad, how would that be? before exhaust i got PI heads and a ported intake

Because cars are funny like that. Mine did the same thing when I did my head swap and used the stock spark plugs and stock gap. I replaced then with a 1 step colder plug and decreased the gap and I wasnt getting the cylinder miss fire code.

 

[tomustang]

ah, that helps alot. thanks bro got a suggestion for a decent budget spark plug alternative?

 

[mogs01gt]

here you go,
http://forums.modulardepot.com/showthread.php?s=&threadid=2218

 

[tomustang]

gapped the plugs to .040, got more performance out of them but it still pulls the misfire code.

 

[mogs01gt]

Did you clear it?

 

[tomustang]

i cleared it and i came back on. still dont have a clue. i'm leaning twards the injector now.

 

[RysRed96GT]

so a smaller gap for headswapped cars will make more power? i might try that. are u using copper or platinum plugs?

also, before you buy a new injector, just swap 2 of them and see if the misfire switches the other cylinder.

 

[allutz]

wouldnt hurt to look for a vacuum leak at the cyl. #1 intake runner.....did you replace the intake gaskets too??? it doesnt take much of a leak to set a lean or misfire code...

 

[mogs01gt]

so a smaller gap for headswapped cars will make more power? i might try that. are u using copper or platinum plugs?

also, before you buy a new injector, just swap 2 of them and see if the misfire switches the other cylinder.

wont make more power. When you have more air flowing into the cylinder and with a large gap, that extra air in the cylinder sometimes can disrupt the igniting of the air/fuel.

 

[Gearbanger 101]

well, 62 bucks for a injector. before i spend $ on this is there another possible reason why this is comming up as a misfire?

What for a stock 19lb injector!?! .....screw that, buy a whole used set on Ebay for that price, then flow match them.

 

[mogs01gt]

i cleared it and i came back on. still dont have a clue. i'm leaning twards the injector now.

If its only happening in the number one cylinder, take the injector out from #2 and see what happens.

 

[tomustang]

so a smaller gap for headswapped cars will make more power? i might try that. are u using copper or platinum plugs?

also, before you buy a new injector, just swap 2 of them and see if the misfire switches the other cylinder.

oh yeah. to mogs01gt for that power increase. very very noticeable. ill try the injector switch.