R32 Gtr Rb26 - Problems With Idle And Backfires

[Acrula]

Hi there!

Recently my car just got a preoblem I cant figure out of.

I am currently running Apexi PFC D-Jetro (MAP sensors).

The issue is that when I drive normaly, on low RPM the car is hesitating and "jumpy", and when I release the throttle it will backfire all the time until I apply throttle again.

While this happens I can see on my hand commander that the ignition timing is going up and down at the same time as the backfires occurs.

Also the idle is rough, going up and down from about 900 rpm to about 1.3k rpm.

However, I can park the car and go for shopping or even fuel my car, and when I start it and drive, it behaves perfect with no backfires or no hesitation.

Also, about 70% of the time, if I rev the car and empty the gears to the revlimiter the issue will go away for a while, and then it comes back.

I have tried to wiggle cables, checking hoseclamps, replaced sparkplugs, replaced the CAS. But this issue is really something I cant figure out.

Anyone here with some tips on troubleshooting this issue?

Edit:

Here is two small videos that I made. taken only minutes after eachother, after some shopping.

Bad idle:

https://www.youtube.com/watch?v=T2MG9Pf_jeU

Good idle:

https://www.youtube.com/watch?v=h7mUYNZii0U

Best regards,

Thomas

Edited August 21, 2015 by Acrula

[STATUS]

Cas is a common cause of this, try a fresh cas.

[iruvyouskyrine]

He said he had already replaced the CAS. Hopefully it was with a known good unit.

[Hadouken]

Make sure bolts in cas are tight?

[Acrula]

Hi there all,

Thank you for taking time to reply on my thread.

I have tried allot of things now back and forth and it seems that I have managed to get the backfiring gone when releasing throttle.

There was a loose nut on one of the throttlebodies and it seems that it had screwed itself out abit, making it not sealing proper when throttle is shut.

I did really hope that this also was causing the bad idle, but the idle is still the same, rough sometimes, sometimes its not. Today i replaced the AAC valve, and cleaned it really good before install.

I also replaced the PCV valve, since it is so easy, I just had to try it.

Then I also replaced the TPS, since i noticed on my commander that the black dot for "idle" didnt tick when releasing the throttle, after TPS replacement there is now a black dot on "idle". But yet, the idle is still rough.

So I guess I have to try some more stuff tomorrow then, and I will update if things go better:)

Best regards,

Thomas