Rb25det Rapid Miss Fire

[.::Matt]

Hey guys...

Yes I have searched but came to no help...

So, I have a 96 R33 just with basic mods, stock turbo, cooler, exhuast, Powerfc. It has a alimighty rapid miss fire. It only happens when i have my foot flat and go over about 4500rpm, Say you put your foot down quater the way down it can rev right up same if you just give it a rev under no load... What I have changed are the coils (Superspark), tryed two sets of spark plugs gapped to .8, changed fuel filter. It doesnt happen all the time but atm everytime I drive it. I can see in the engine bay that there is a earth strap near the turbo that is broken so i measered the Ohms between the engine and the chassis and it seemed alright. so if anyone could help it would be great i have taken it to a workshop and they where pretty hopeless (Well known workshop to).

Cheers Matt

[.::Matt]

Alright just a few more things i have found out today well when it missfires the engine light turns on I played around turning different warnings on and off, in the powerfc and it seems to be the knock sensor... The car is running rich blowing black smoke when the mis happens and you can smell it... Could it be a faulty knock sensor which is casuing it to run rich would this casue the miss or is my idea totally wrong?? Anways any help would be great

Cheers

[PM-R33]

What's the knock count on the Power FC read when the engine light comes on? It's most likely just pinging its head off, safest bet take it to a workshop to check the timing and AFR's over 4000rpm, most likely leaning out a bit up top.

Didn't run some crap fuel in it recently?

Edited December 21, 2008 by PM-R33

[DrewII]

coil packs, spark plugs or coil pack loom. i'm going through same problem right now too. will let you know on friday what it was.

[.::Matt]

Had good fuel in it have been threw a couple of tanks. The knock count is high when the engine light comes on but the miss doesnt happen when the light comes on only happens above 4000rpm with foot flat, So I dont know if im chasing two problems now. Can you pick a new coil pack loom anywhere or is there only second hand ones?? and workshop wise around Brisbane what can you recommened?? I had a bad run with the workshop last time over a few little things where it got tuned, like cross threading spark plugs and not telling me and letting me find out the hard way

[lcy]

i had the same problem.

CHange to splitfire. Problem solved

Right now its happening again with Power Fc and bigger turbo....

[PM-R33]

Hmmm sounds like two seperate problems, a missfire problem and a knocking problem.

For the knocking its going to be in the tune.

As for the missfire, if you have changed plugs (BCPR6E's?) and it still does it, then most likely it is the coilpacks or the loom.

As for the broken engine earth, there is still a main engine earth on the block underneath the plenum, however i would still add a couple more earths off of the head. I picked up a Pivot engine earth/voltage stabilizer kit for $50 brand new to test it out (retails for $300 on nengun at the moment, f**k that!) and straight away noticed the car was easier to start and the voltage didn't drop down as low on start up anymore. So extra earthing of the engine definetely helps a tiny bit. Add another earth near the coilpacks to the body of the car just in case, it can't hurt.

Edited December 21, 2008 by PM-R33

[Guilt-Toy]

go and see mark at Godzilla Motorsport, he will be able to fix it for you

[DrewII]

really strange that its happening to so many cars at this very moment.

[jasont82]

yeah im having this same problem too. ive had problems with splitfires though. ive had to send three back so far. had car running perfect again after sending back splitfires when i went over seas. just got back after 14months, useless brother wasnt starting it up every few days so pretty much sat there for over a year.

then they started it up just before i got back and it was running terribly so took out my wolf3d and put stock ecu back in. would run ok but miss fire at 4500rpm. so i figure its another splitfire coil pack. think i may have received a dodgey batch or something considering its the 4th one to die.

put the wolf back in so it ran ruff unplugged each coil to see which one made no difference. this is how i diagnosed last three times, replaced with a stock one and ran fine again.

this time thought it was the 5th one, changed for stock one, runs ok at idle now but still mis fires at 4500. so put stock ecu in again but still the same.

has gotten worse now sometimes doesnt even idle with stock ecu now. and can missfire anywhere through the revs as low as 2500rpm. seems to come and go with the missfire at idle but at 4500 does it everytime

not sure how to solve this one. possibly two coil packs gone at same time??? wiring loom? tried to search for "how to test coil packs" but couldnt really find an answer. any suggestions?

cheers