Irregular Engine Misfire 1996 R33 Gts25t

[shaneAS97]

A week ago I noticed my car started to misfire irregular at idle. Wasn't constant just a miss every few second. Also started missing under low rpm acceleration and was fine a 5000+ rpm. I changed out the old spark plugs with new ones and the car ran Amazing.... for about a week. The car has started showing the same symptoms as before. I just don't understand why the car ran so well after the installation of the new plugs only to start misfiring again a week later. Any advance is welcome.

Thank you

[Ben C34]

Perhaps your plugs have fouled due to running rich.

Seeing as you have given no info at all in the car I'm going to guess.

It is stock. Except for an exhaust and raised boost. And a different Bov. And you only recently Bought it. And not sure if it has a tuned ecu or anything. But it goes hard. And impresses your mates.

[niZmO_Man]

'Tuned ROM' perhaps?

Tried another AFM?

[shaneAS97]

Okay more about the car.

I have had it for about 8 months now and this is the only misfire issue I have had with it. The misfire as stated before only occurs when the car is warmed up.

the car is relatively stock. Exhaust system with Test pipe. Air intake. Boost gauge and turbo timer.

as far as I know the car has not been tuned.

thanks

[niZmO_Man]

Pull the spark plugs out and have a look at them.

Could be AFM, could be weak coilpacks, could be something else.

[shaneAS97]

I'll pull them out this weekend. I don't think it's the maf. I cleaned it and when I unplugged it will the car was running the car stopped running. I noticed that the misfire only occurs at idle and from 1000rpm to around 2500rpm. I also noticed that at high rpm there is like a screaming noise coming from the engine bay. I don't know if the misfire and this are related or not.

Edited May 5, 2015 by shaneAS97

[zoomzoom]

Possible exhaust leak which also causes the o2 sensor to give incorrect readings.

[shaneAS97]

I'll definitely take that into consideration.

thanks

[zoomzoom]

The handiest tools for these sorts of things is a consult connector and a logging program. Fluctuating timing, or fluctuating injector values would be a good giveaway of a problem. You'd also be able to see the o2 sensor value. But some misfires can be cryptic. Ive got an occasional misfire at low rpm. I have new plugs, coilpacks, stable timing and injector pulses.... but still an occasional fart at idle.

[shaneAS97]

Does a consult connector basically connect to the ecu and them plug into a computer with a logging program on it?

[zoomzoom]

Yes, http://www.ecutalk.com/

There are also links to freeware consult software.

[shaneAS97]

Alright I'll look into that aswell