Cylinder 3 misfires randomly

[SubieJake]

Hey all, I have been searching a little to try and find an answer to my problem but i haven't been able to find anything that correlates to my problem, if there is a thread i'm sorry and please link me to it thank you.

 

Basically whats happened is my turbo on my 2007 legacy gt blew vf46 was in there, and i recently swapped to a vf52 for a little more kick, i have been working with tuning alliance and having them tune my car which they are fantastic and i'm happy these forums have recommended them.

 

anyways, i have a Catless DP, to stock exhaust midpipe, then a muffler delete.

 

now currently my car is misfiring on cylinder 3, okay not a problem ill check it out, i did recently change the spark plugs before my tune so i cancelled out the spark plugs, i swapped over the coil packs to see if its that but its still in cylinder 3.

 

NOW whats weird and confusing about my misfire is that, sometimes when i cold start the car wont misfire, but then while its warming up it'll start misfiring.

 

but it doesn't stop there my car will continue to jump from misfiring to not misfiring to misfiring again, and i have not reset the ecu or anything between the times of misfire/not misfiring, and it will be completely random occurrence. Also when it misfires my Cobb AP2 will read cylinder 3 roughness and hits 0/99, which is very high. i have no idea what to do, I am going to do a compression test as well as swap over the fuel injectors to see if thats the problem due to the fact that i smell gasoline when idling.

 

another thing to note is 2 days before i started misfiring i threw a P0440 code, i cleared the code and has yet to come back on. but now i misfire....

 

Any help would be appreciated even if its a link to another thread for this problem thanks a lot.

[awfulwaffle]

Try swapping the plugs themselves cylinder to cylinder, and injectors too. Lowest hanging fruit. Then if you still have an issue, I'd look at valve clearances and compression/leakdown. May be a good idea to drop a borescope into the plug hole to see if there's any obvious signs of trouble in the cylinder.

 

P0440 shouldn't have anything to do with the misfire, and is common on these cars.

[SubieJake]

Try swapping the plugs themselves cylinder to cylinder, and injectors too. Lowest hanging fruit. Then if you still have an issue, I'd look at valve clearances and compression/leakdown. May be a good idea to drop a borescope into the plug hole to see if there's any obvious signs of trouble in the cylinder.

 

P0440 shouldn't have anything to do with the misfire, and is common on these cars.

 

Thanks for the reply, I have swapped over the plugs and its still saying cylinder 3, I did a compression test on cylinder 3 today and came back at between 140-150

I have yet to swap the fuel injectors yet, it started raining so I ran out of time. I’ll do the injectors tomorrow and use a Borescope as well

[Infosecdad]

If you've moved coils, then I would suspect either the connector for coil #3 or the injector there.

It's possible it could be the intake gasket, especially if you don't have the newer orange gaskets, but I would put that at #3 after the coil plug and injector (and its plug).

 

May also be that the injector seals are leaking, just be careful to try to get them in cleanly to help when swapping.

[SubieJake]

If you've moved coils, then I would suspect either the connector for coil #3 or the injector there.

It's possible it could be the intake gasket, especially if you don't have the newer orange gaskets, but I would put that at #3 after the coil plug and injector (and its plug).

 

May also be that the injector seals are leaking, just be careful to try to get them in cleanly to help when swapping.

 

Thanks for the suggestions, i went out yesterday to remove the fuel injectors unfortunately i don't have a garage and it started to rain but when i got to the fuel rail, the cylinder 3 fuel injector had no bracket holding it down with the screw so once it stops raining and i'm able to take a better look that might be the cause, and maybe that's the reason it misfires then doesn't. ill keep this updated

 

thanks again

[SubieJake]

So update on my problem I pulled the cylinder 3 fuel injector and it’s cracked I’m guessing that’s the problem guess it’s time to upgrade