R33 Misfire, Just Changed Exhaust

[Guest Rotary20B]

Just changed cat to a high flow magic, and a trust cat back exhaust.

Now up around 5-5500 rpm the car will always misfire, only happens at high rpm, would it be because it is running too rich?

This is the only mods the car has apart from a pod, it never did this before the exhaust change.

Any ideas? I did reset the ecu as well.

[Dobz]

changing the exhaust or the cat won't affect ignition, it might play around with fuel mixtures a bit but the ecu should eventually adjust to correct it.

check the plugs and see if theyre fowled up

[12DFY]

Hey mate, because you have upgraded your exhaust the car will actually boost more, the problem you mention sounds like youre spark plug gap needs to be reduced to cater for the increase in air going through youre motor. Drop plug gaps down to about 0.8mm, should solve youre problems.

Bigger exhaust = more air out, which means more air has to go in

[MKDR33]

regap ur spark plugs as mentioned above and seal ur coil packs..

[Guest Rotary20B]

Thanks fellas, will do

[Guest Rotary20B]

One more thing.. have done a search, but they say to gap at 1.1mm

Which ngk plugs for rb25det gapped at .8? (stock engine, turbo, just pod & high flow cat back exhaust

Edited August 14, 2006 by Rotary20B

[Guest Rotary20B]

Well I changed plugs, bought a new set of copper plugs and regapped them to .8

I didn't want to tape the coils as I couldn't see any cracks at all.

It worked fine on stock boost, then last week I fitted the turbotech boost controller, 10 psi and it would misfire, turned it back down to 7psi and no misfire.

A week later and now it even misfires at 6psi.

I really couldn't be f**ked playing around with taping coils and would just take the plunged and buy a set of splitfire coils if I knew for sure this would fix the problem, any ideas?

[Guest Rotary20B]

Also, do people run 1.1 or .8 plugs with splitfire coils?

[Kennedy]

Well I changed plugs, bought a new set of copper plugs and regapped them to .8

I didn't want to tape the coils as I couldn't see any cracks at all.

It worked fine on stock boost, then last week I fitted the turbotech boost controller, 10 psi and it would misfire, turned it back down to 7psi and no misfire.

A week later and now it even misfires at 6psi.

I really couldn't be f**ked playing around with taping coils and would just take the plunged and buy a set of splitfire coils if I knew for sure this would fix the problem, any ideas?

Tape them up now to be sure. It's only an hour job. If it fixes then you will know its definitly cracks in your coils...then you can choose to seal them more permantly with silicon or "just buy splitfires". $5 Vs $550.

Same thing happened to me and I could not see any cracks at all...but apprantly they were there coz silicon fixed it.