Rb20Det Problems

[MrWindsurf]

Hi everyone,

My mate has an r32 gtst (auto) and its been playing up recently I was wondering if someone might know the problem.

Symptoms:

Irrattic Idle will be anywhere between 1600 and 400 it also stalls sometimes

The computer seems to be in limp mode when driving can't rev past 2500-3000, however you can free rev the car to redline no problems and sometimes

in 1st it will allow you to rev over 3000rpm its weird.

I checked the error codes on the computer and it did come up with 12 (MAF) but this could be because at one stage the car was running and I unplugged the AFM.

After it gave the error code of 12 I tried turning the car off (from on not started) again and then on to check the codes one more time and got 55 (no error) so we tried to

swap the afm over from my 32gtr but it seems to be a smaller diameter not sure why but yeah I'm assuming the reading would be different because of the size. So that

didn't really work

Maybe could I borrow someones AFM if they have time to check that is definetly not the problem.

Thanks in advance

Andrew.

[brendo.r32]

Sounds like idle control valve or o2 sensor.

[Psymon]

Sounds like idle control valve or o2 sensor.

Wouldn't be the o2 sensor.

[brendo.r32]

Maybe not, but my 32 did exactly the same thing when the o2 started to die. The idle would hunt around and would constantly go in and out of limp mode.

[Mohsen]

afm?

my o2 sensors stuffed and the cars fine.

also re shifting, my car revs to 6000 before it shifts when i fang it lol

[MrWindsurf]

Hmmm so might be the o2 sensor ey, might be worth a look thanks for the advise.

[Psymon]

Hmmm so might be the o2 sensor ey, might be worth a look thanks for the advise.

The car should idle and run even with a stuffed o2 sensor. I drove mine for a week with the o2 sensor unplugged and the only difference I noticed was a slight increase in fuel consumption.

[MrWindsurf]

Yeah I have just been reading a thread about the o2 sensors so maybe I'll unplug it and see if anything different happens just to check. This is really annoying me and because its not my car I dont wanna go spending hundreds replaceing afms and o2 sensors if they are not the problems

[lukebaldan]

The problem you describe sounds 100% like afm. I can replicate this problem by disconnecting the afm. I highly doubt it's the o2 sensor, you'll find your car should run fine without it albeit higher fuel consumption. You'll eventually get the check engine light 2 to 10 minutes after the car is started when the o2 is disconnected.

Edited December 6, 2010 by lukebaldan

[blind_elk]

I checked the error codes on the computer and it did come up with 12 (MAF) but this could be because at one stage the car was running and I unplugged the AFM.

Then reset the ECU and see what error codes come up.

Could be a sticking AAC valve causing the idle hunting.

[MrWindsurf]

Yeah I might give that a go tonight, reset the ecu then check for error codes again :-) Hopefully I get 12 again. If this is the case is there anyone who can come around and let me swap there one in to confirm that, that is the problem? I guess it would have to be from a gtst because the one from my gtr is a smaller diameter afm so i'm guessing it would send the wrong signals to the ecu.

[brendo.r32]

Try cleaning the afm probe with some carby cleaner, fixed mine (although run map sensor now). But mine didn't cause any idle issues, just cut out randomly when accelerating.

[MrWindsurf]

Yeah I tried that already so, not sure what the deal-e-o is will reset tonight and post results

[Rekin]

Its the AFM and you cant just swap any AFM onto the r32 and assume it will work.

RB20 AFM works on RB20 engine. Anything else will need a retune. (ie. z32 afm)

[MrWindsurf]

ahh ok well if thats the case does anyone have an afm i can borrow from an rb20det or can drive round and help me swap to see if thats definetly the case???

[Wheezy]

R33 Series 1 AFM is identical if that helps

[MrWindsurf]

Update: so I disconnected the battery to reset the ecu over night ... re-connected and tried to start the car all it does is crank over, doesn't even fire up :S so now I have nfi. If it was the AFM that was on the blink the car should still start right?

[brendo.r32]

maybe your ecu or cas? Im just shooting in the dark though.

[MrWindsurf]

Another Update: Well seems that if i spray carbie cleaner into the throttle body the car will fire up on the fumes, which lead me to believe it was the fuel system. I found where it plugs into the fuel pressure reg and unplugged it before that, when i am cranking the car there is no fuel coming out of the lines. So either the fuel filter is blocked or the fuel pump is knackered. I think I might be getting somewhere now tho

[brendo.r32]

Just remember a faulty cas will stop the injectors from firing.