Increased Boost and still misfiring

[QuickR33Melb]

Guys I'm going crazy!! I just paid for a highflowed RB turbo and after picking up my car from the shop that did all the work late last week I'm still not happy!!

The work they have done seems to be fine however when I picked up the car the owner of the shop said that they had run the car on the dyno and the spark plugs appeared to be F$%^-ed so they could not tune the car over standard boost.

So the very next day I went to Bursons and picked up 6 new plugs and gapped them to 0.8 and fitted them. I then set the boost to around 8-9psi which should be fine however I appear to still get detenation around this boost level. (The feeling of misfiring at high rpm when I give the car throttle)

IT'S DRIVING ME NUTS!!

Any ideas what is causing this? I have searched the forum and in the past the answer to this question is regapping the plugs however I have done this and the problem continues!!!

[Bass Junky]

What ecu or mods?

[WLD747]

Sounds like you need new coils or you have 2 much timing.

[QuickR33Melb]

Mods are pretty basic- Air pod, 3" front pipe and cat back exhaust, boost controller, new turbo

[crooser]

Dodgy afm - check/clean connections

try getting hold of another to test

[Guest INASNT]

Mods are pretty basic- Air pod, 3" front pipe and cat back exhaust, boost controller, new turbo

FMIC, any sort of piggy back ecu???

[Husky33]

If it was your coil packs i'd say it will be misfiring all the time, not only on boost. I'd say check your timing...but also check things like afm, give it a clean maybe

[Gav]

Ignition module is also another possibility. Spend an hour or two one afternoon with another Skyline owner and swap module and coil packs to see if this does the trick.

[Abo Bob]

If it was your coil packs i'd say it will be misfiring all the time, not only on boost. I'd say check your timing...but also check things like afm, give it a clean maybe

Not necessarily all the time as myself and 666DAN know too well.

[Black33]

Guys I'm going crazy!!  I just paid for a highflowed RB turbo and after picking up my car from the shop that did all the work late last week I'm still not happy!!

The work they have done seems to be fine however when I picked up the car the owner of the shop said that they had run the car on the dyno and the spark plugs appeared to be F$%^-ed so they could not tune the car over standard boost.

So the very next day I went to Bursons and picked up 6 new plugs and gapped them to 0.8 and fitted them.  I then set the boost to around 8-9psi which should be fine however I appear to still get detenation around this boost level.  (The feeling of misfiring at high rpm when I give the car throttle)

IT'S DRIVING ME NUTS!!

Any ideas what is causing this?  I have searched the forum and in the past the answer to this question is regapping the plugs however I have done this and the problem continues!!!

What sort of boost controller have you got?

Are you sure you have the correct boost level, ie. have you got a boost gauge to check it?

ps. did you go to TVE to get your car tuned, I thought I remembered someone mentioning that recently?

[Guest RedLineGTR]

since the workshop installed it i rekon they should have some idea of what could be the problem... Or do they just hi flow the turbos and dyno cars??

[GTRgeoff]

Starting from scratch here, what car/engine, what plugs have you got, when did you last change your fuel filter, have you got too much timing advance, what gear is it most prevalent in and throttle position, have you tested the resistance of the coil packs (eg RB25DET about 1.3 KOhm) across the centre and right pin (I think, any other combo is nothing anyway in that range), what fuel do you run, have you pulled the fuel return line off (put a container under it and just do it in the engine bay) and examined the volume of return flow at idle and mild throttle to determine fuel pump capability (I have come across 2 buggered pumps in the last week), is it auto or manual????

Any and all of these could be causing your problem, eg my auto cuts power hard like a major fuel cut at over 7psi of boost, regardless of what I have done, and the girl drives it so less is good anyway, and it runs perfectly otherwise.

[Cubes]

What plugs did you go?

A heat range cooler?

[sprint32]

I'd normaly say ignition timing as well. What did they do with the 'highflow' turbo? Did they modify the exhaust side in any way. the reason I ask is maybe the turbo is now surgeing and feels like misfiring. But maybe the coils are just dirty? (carbon tracking).

[Pandaemonaeon]

You will be likely to have a problem with the AFM. What you have done is increase the flow rate in the intake by increasing the flow on the turbo. When you are flooring it the computer is reading throttle poistion, boost level etc, but all of a sudden the amount of air the AFM is ready is a hell of a lot more than it should be for the boost the car is running. There is also a pretty good chance that the fuel pump can't keep up with the demands.

[Black33]

but if he's put it back to 9 psi and it's still doing it - he shouldn't be maxing out his AFM or fuel pump at that level.

[Pandaemonaeon]

Just spoke to a friend who has this problem and was told it's not a matter of the AFM being maxed, it's just reading a different amount to what the ECU would expect. He has a T3/T4 on his 25DET and it does it even on standard boost.

Note: This is on a R34 engine and ECU so could be slightly different to R33

[Black33]

yeah but that would make it run rich and give you a flatspot, that what an safc is for - it shouldn't feel like it's misfiring

[rev210]

did you say detonation?

If so it isn't the plugs fault its probably the fact that you are running out of fuel. I noticed you have a high flow turbo and no mention of a bigger fuel pump. Get ready to say hello to a broken ring land or three.

you will need a bigger fuel pump and injectors, or at least an adjustable fuel reg and big pump.

[Black33]

how could this be detonation if it still happens at 9psi - stock fuel pump will be able to handle this easily