Still Misfiring. Not Plugs, Not Coil Packs, What else?

[ix9]

Aight....

Been having this misfire happening on any boost above 7psi... and it's pissing me off. It happens ALWAYS between 4000rpm and 5000rpm and only when i'm giving it some

I've replaced plugs about 4 times since i've had the car.... it runs fine for about a day or two then starts to misfire again.

I'm using NGK BCP6RES gapped to 0.8mm.

I've tested my coil packs las night, they ALL spark OK and all measure 0.7ohms across pins A and B.

My next question is, what ELSE could cause a misfire if it's not plugs or coils ?

[Guest Robo's]

Too much fuel, beleive me!!

I was like you, changing plugs in and out, coil packs, on 7psi it would slightly miss at full throttle, turn the boost up and it was terrible.

Then i got an SAFC, took some fuel out, and now she flies, no misses!!

[ix9]

No shit... ? just too much juice ?

my plugs do get pretty black!

My S-AFCII should be arriving very soon, so that sounds like the go....

[RbHed]

my friends skyline got the same problem....

changing plugs and coils, never thought it be a fuel problem.. i think its time to invest in a s-afc

[GTS-t VSPEC]

Kym, Get the SAFC, get it tuned, and I'm sure it will help:D

[crooser]

when you say misfire, do you mean a single miss or feels like its a held choking feeling. power comes back on after 5000rpm?

if this is the case, your AFM is dodgy.

swap it with a freind's working afm and i'm betting your problem is gone.

cheers

[DCIEVE]

i had the same problem, kept looking for things wrong with the motor, never thought that it was just runnning to bloody rich on the other hand, now its tuned its missfiring again...hmmmm

[Dion_180sx]

AFM???

[bless_you]

hey kym

experiencing the same prob as you, i know what it is like.

i just had my safc II installed and tuned on tuesday... didnt fix it... helped it. i have tried all avenues thatyou have except fro AFM...

i am heading to cypher on saturday where they are going to swap over a AFM for me and see if that fixes it... cross fingers... i will let you know pal

best of luck

Nate

[jayR33]

I had the same problem. Once i hit full boost it would start to splutter at around 4000rpm - 5000rpm. Once i installed my pfc it removed the splutering completely. But yes it can also be the afm.

[ix9]

Cheers guys,

Well, I'll just wait until the AFC is in and tuned, and if it still does it, i'll be looking at the AFM.... daym!

Maybe it's better to go for a Z32 AFM ? How much are they in comparison to a stock AFM ?

crooser,

By single misfire, i mean, it gives about 3-4 big pops consistantly between 4000rpm and 5000rpm.. then power comes back on after 5000 and it runs fine till redline...

so frustrating...

[bless_you]

kym,

if the AFM fixes it this saturday, i will let you know.

Then when i get a new one, we can meet up and you can wack it on yours and see if thats the problem.

Nate

[rb25]

ii've seen this before, was a dodgy AFM

[blind_elk]

In a recent Zoom!, Martin did an article on compressor surge. The symptoms are as you describe. Occurs particularly in 'hi-flowed' turbos that are not properly matched to the engine.

The car in question was a R33 with SAFC. They retuned the SAFC for leaner fuel and more advance - it reduced the problem, but didn't totally cure it.

[Nexus_SiX]

I've had the same thing on and off for about 14 months now. Tried diff plugs gaps etc. Have coated the coil packs with leccie tape and all sorts of things. I got a PFC and it made a "slight" improvment.

I did read on here about someone who went crazy with CRC around the packs and their area. I tried that and it worked for about a month. But its back now

[Gav]

Kym

I'd lay money on the igniter module being on the way out.

Borrow a replacement from a mate to diagnose.

Also - the ohm test of the coilpack I've never found to be reliable.

Borrow a coil pack at the same time and swap them out one by one.

Funny thing was when I was doing this, by the time I went fanging up my favourite hill for the 6th time in an hour,there was a cop at the top with a speed gun! Obviously the locals got a bit pissed off.

[rev210]

Originally posted by Strich9ine

Cheers guys,

Well, I'll just wait until the AFC is in and tuned, and if it still does it, i'll be looking at the AFM.... daym!

Maybe it's better to go for a Z32 AFM ? How much are they in comparison to a stock AFM ?

crooser,

By single misfire, i mean, it gives about 3-4 big pops consistantly between 4000rpm and 5000rpm.. then power comes back on after 5000 and it runs fine till redline...  

so frustrating...

Timing/spark issue mate.

The ECU retards the timing around that mark, possibly too much in your case. The coils may need a bit of a light sanding to ensure good earthing contact when they are bolted up too.

If you like come round this morning and I'll have a qiuck look if you want. (I'll PM my mobile No. and address).

Dave

[skyline33]

also try reseting your ecu

[ix9]

bless_you,

Thanks buddy.. let me know how it goes!

blind_elk,

I have a stock turbo compressor surge is like you say, happens more on hi flowed turbs.

Nexus,

It still happens on yours too? what the?

Gav,

It's the seriesII engine.. so no igniter module just coil packs...

rev,

I've used degreaser/crc and wirebrushed/sanded back the coil packs etc.. but still to no avail...thanks for the offer, but i'll be replacing plugs today

skyline33,

Done that too mate... doesnt help..

st00pid cars...

[skyline33]

if you've tried all the above, then the only thing you can do is take it to a place which has a diagnostic tool. my friend had a similar problem and took it to a place, they said the knock sensor need to be reset via the diagnostic tool.

also make sure that everything from the turbo to the airbox is on properly.