RB20DET overfueling

[zforce]

Hey guys,

My RB20DET is currently running very rich. I am not sure why this is, however i am hoping you guys maybe able to shed some light on the situation. Currently i have cleaned the spark plugs, coil packs, pod and AFM and with no luck.

The car idles fine, however there is alot of black smoke coming out of the exhaust at idle, and when reved. It doesnt sound like it is missing a cylinder, however i was thinking that maybe it has gone into limp mode, but i dont see how this is possible when teh ECU diagnostics comes back as 55 (all clear).

I guess what i am worried about is whether if there is some internal damage could cause a problem like this (rings are gone?, head gasket? etc). I have had very similar problem in the past and i fixed it by doing what i mentioned above, disconnecting the battery, disconnecting the ECU, moving the loom (apparently there is a wire lose? and this is causing it, is that possible? as i took it to an auto electrician and he played with the wiring loom and could make it do the problem mentioned or fix it but moving the wiring loom, however it wasnt consistent...). What other things could be causing overfueling, is there something simple i havent checked (except the injectors)?

Any help would be great!

[Cubes]

Mine did this once after the AFM was removed to fit an Intercooler.

Started up with a bit of a lumping sound. I could see a small stream of black smoke exiting the exhaust.

When reving the car did not feel as free as it used to with the rev's quickly dieing once you let go of the throttle.

On the dyno it blew quite a bit of smoke.

Removed the AFM fitted an R33 one that was sitting there. Did the tune slapped the RB20DET afm back on and all was well. I've had it play up every now and again since then but its hanging in there. I put it down to maybe a dodgy solder inside the afm or possibly a dodgy plug.

Once when driving home it lost all power, boost was being made but no power, removed the afm plug, plugged it back in and all was well.

[zforce]

Its not a piston ring or anything major like that?

[Sydneykid]

Hi zforce, sounds like an air leak between the AFM and the engine. First thing I would do is check all the pipe work very carefully. If that isn't it then a quick leak down test at your local workshop will confirm that everything is OK inside the engine.

Hope that helps

[Amaru]

Could be leaking injectors, i have the same problem at the moment in my rb26 and its attributed to leaky injectors.

EDIT: And I just read your post in full and saw the part where you said except injectors... my bad :Oops:

[TTT]

in reference to what SydneyKid has said..

You can make a simple device to help you out..

http://www.vfaq.com/mods/ICtester.html

Piss easy to build and really handy for leaks..

on another note.. could it be the Oxygen sensor on your dump pipe that is dead and causing your car to over fuel?

[zforce]

Well the reason why i am concerned whether it is internal problems is because my mate gate it a hit and hit red line and then thats where the problem started (didnt hear a bang or anything), just started to stutter a little bit then got a bit worse (as the plugs got more fowled) etc to the point where it basically wouldnt idle, put the acel down and wouldnt do anything, then i clean the plugs and it started to run better again (still rich) but driveable then got worse again to the point where it couldnt be driven (same as before), then i cleaned plugs, AFM, pod, coils etc and it idles fine, just really rich, put the accel down and responds fine, just really really rich like i said so could it be piston rings or something like that? It just seems to me that it cant be like a head gasket, piston ring, bent valve etc as it would be consistent and not go from ok to bad. Cheers guy.

[zforce]

Thanks for the responses guys, i will check my IC piping, O2 sensor, wiring loom and lastly the injectors. Hopefully that will solve the problem, i just hope it isnt anything major...

[blind_elk]

Save your time checking the O2 sensor - it really only works on cruise, not when you are accellerating / boosting.

[zforce]

Cheers, so you guys dont think it is anything major?