V35 250Gt Misfiring

[beercat]

Hi everyone, trying to figure out what's wrong with my car. (250GT VQ25DD)

Only have a Injen cold air intake, although it was meant for a G35 and so I have 1 small hose, i think it's for vacuum that's disconnected.

It started with a very slight, barely felt, misfire during idle.

Now it's built up to be quite bad, spewing black smoke while driving, with bad fumes on idle.

Consumption's shot to hell, if I idle too long it'll go into limp mode, and sometimes it's hard to start.

I've changed the spark plugs, then I changed my coils - to wrecker items - and nothing's changed.

My plugs are cooler than recommended though; NGK LFR7s instead of the 5s, but the problem existed before I changed my plugs.

I can try running hot plugs again, but I think the problem lies elsewhere.

ECU reported initially that Bank 2 was running rich. I got my hands on a OBD2 scantool and reset everything, including ECU learning.

There was no change, then both Bank 2 and Bank 1 were reported rich.

I've heard on the Golf's when the high-pressure pump goes faulty it continuously dumps fuel at a high rate, even at low rpm.

I guess I'll try cleaning the injectors next; although do you clean direct injection (high press)injectors the same way you clean tb/port injectors?

Also, the initial problem was more apparent after I decatted; although my car only has upstream O2 sensors.

Edited August 11, 2011 by beercat

[gaz523]

sounds like bad petrol to me