Misfire And Popping From Exhaust

[shotter]

I got my r33 tuned, it currently has a haltech intercepter and high flow turbo that gcg have told me can run 20psi no problems.

My tuner (who is a bit of a muppet)tuned my car at 12psi, because he said the extra few kw wasn't worth it for the extra pressure. He told me he ran it at 20psi and it ran fine and didn't lean out. So after i got the car back i pushed the boost up to see how it would go. At 15psi it really halls and feels like a different car compared to 12psi. I tryed to push it more to 17psi and it started popping out the exhaust and it also had a bad missfire (the car just completely cut for a second) as i was reving the gear out. It also blew off one of the vac lines, so i had to stop and put that back on. I got it back to 15 psi and it's happy. The thing i want to know is what might have caused the popping and missfire, and once your car is tuned, The fuel maps modified and the timing is advanced as much as possiable, How can you get more power out of it?

[Drakey]

prob coils mate... they stock coils??

probably blowing out the spark

[shotter]

Yea the coils are stock. It's funny it would pop through the exhaust sometimes and other times it would be ok.

[Drakey]

Yeh my guess is the coils... thats alot of boost to be running for stock ones..

If i run more than 14psi then mine misfires like that and thats with a 0.8mm gap on the plugs.

Id just stick with 15psi if it makes the car run nicely...

[shotter]

im worried that the car is running lean and detonating. Would the popping noise and the missfire be caused by it running too lean?

[lachlanw]

the opposite of lean , you need excess/un burnt(missfire) fuel in the exhaust for it to back fire

[shotter]

it isn't a backfire (but it does do that sometime with slow gear changes) it more of a quick popping noise for a few seconds that you can hear out the exhaust.

[Drakey]

Misfire mate.... means the fuel isnt being burnt (my guess is from the coils not strong enough)

[geraus]

splitfires! & BCP6RES 0.8mm thats what i got

[MBS206]

Splitfires with 1.1mm gap works even better!

Here's a question for you to think about...

You pushed the car to 17PSi, and mis fires like mad...

Yet your tuner told you it ran fine at 20PSi... Have you not yet thought he hasn't really tuned the car at all?

Get the car on the dyno, do some light load testing, then some full throttle runs. You need to check your AFRs

[Jdfnq]

^^^ what he said.....

get your 'tuner' to show you the AFR's etc etc.

[PHA71L]

coils! mine is doing the same!

[jazzy_j]

Did you get the dyno read out?

[shotter]

Yea im gonna ask for the dyno sheets for the 20psi runs on monday. i can run 13.2psi and it will rev out cleanly with no problems. But anything over that and as it gets up in the revs it will just cut out for a second and the whole car jurks.( im guessign thats a missfire?)

[donkey]

hey there,

my gtr does the same thing, i had a wrx with a link computer, gtr with a power fc, now running a G4 link, when summer comes it starts to run rich, backfires, popping, maybe just check your pugs and see if they are fouled?

[donkey]

woops, ignore my previous comment, mine dosent backfire up high in rev range, its down low, on deacleration etc

sorry

[scotty boi]

my car does the same and i haven't been able to find anyone that knows the problem so thanks for the info, and whats the best to replace the standard ones with. Also do you have to change anything else or just put them in, the problem is so annoying especially underground car parks pops like a b***H.

Cheers scott

[J3TR33]

same problem with my car at the moment, but mine is even worse, sounds like a wrx, time for new coil packs, im guessing its running on 5 cylinders...

[shotter]

So where can you buy these coilpacks from? And whats a good price?

[shotter]

Gotta love this. I called the place that tuned my car and asked for the 20psi dyno sheets. he said that the runs weren't sucessful and that he didn't save the runs.... Now how could he tell me that it ran 20psi and the mixtures were fine??? God this place is getting worse and worse.