Rb20det Weirdness

[Rezz]

I was driving in the city today, lots of stop/starting at traffic lights.

I drive off from the lights then notice that when I lift off to change gears, the revs kinda stay where they are and don't drop... nothing too bad yet, but the car still revved freely as usual.

Then I come up to the next set of lights (red) and stop. The cars revs drop down to idle, then the engine starts fluctuating, from idle up to about 1,500rpm and back again... continuously until the lights go green again (about 1 and half minutes).

Then the lights go green and I take off again, this time when revs rise and it's just about to hit boost, the car SHUDDERS so much (like lurching back and forth), that I just instinctively change gears... then when I build up speed again and almost hit boost, the car starts shuddering again so I change gears.

Then the at the next set of lights the car starts fluctuating revs again... Geezuz. So I just turn the ignition off and wait for the lights to go green. When they do, I switch the car on again and viola! Back to normal...

Can ANYONE diagnose the problem?

[Rezz]

No one even gonna try...?

[d0p3y]

Is it running stock ECU ?

I suspect its sensor related though..

Edited July 5, 2006 by d0p3y

[Rezz]

Yep stock ECU. Only running cat back 3" exhaust, big intercooler and about 10psi... although I don't have a boost controller of any sort... thats what the GReddy boost guage says.

So what sensor could it be?

Just to add, I find that when I go off throttle, sometimes it feels like the throttle body is completely shut, with proper engine braking happening... but other times it feels like (even though I've taken my foot completely off the accelerator) the engine braking isn't happening at all... almost like it's holding throttle as in not accelerating or braking. This I can live with, but still I don't know what it's happening intermittently.

[blind_elk]

Not sure about the shudder, but the idle sounds like a problem with the AAC valve.

It's been covered a gazillion times - go searching.

[Rezz]

Not sure about the shudder, but the idle sounds like a problem with the AAC valve.

It's been covered a gazillion times - go searching.

Ok we'll do. Tahnks

Anyone have any idea about the shudder, and the off-throttle holding revs weird thing?

[FOG35]

could be alot of things, tho my bet is either a faulty AFM or a vac leak before the turbo (check the hose going from the top of the rocker cover to the intercooler piping before the turbo).

[blind_elk]

Could also be the TPS - again, gazillion posts.

[AMS]

Thats basically the same thing that was happening to me... couldnt hold idle, bounced off revs when boost came on. Turned out to be the AFM. But a simple air filter clean did it wonders too

[Rezz]

Thanks for all the relies guys, I've got something to go on now. Cheers

[HKS R32]

Thanks for all the relies guys, I've got something to go on now. Cheers

check the afm plug

[PHATR32]

and the afm solder joints

[Remix-]

Sounds like it went into ECU Limp Mode.

[Rezz]

Sounds like it went into ECU Limp Mode.

Any idea why it would? Also, is 'limp mode' something that can be reset just by turning the ignition off then on again?

Weird I tell ya...

[LZYSKY]

the exact same thing happends to my mates r32. Been going on for about 4 months now, and hes taken it everywhere to get it fixed, changed EVERYTHING possible that could be the problem and still not fixed so if u actually find out whats wrong could u pm me the problem and what needed fixing.