Reference: Skyline GTR Idle Stalling Problem

Is very annoying if you having this problem because it will make you like a paranoid everytime you stop at traffic light, decelerate for cornering and engine can't start after your engine warm. Unfortunately, I had this problem after few weeks of purchase my Blue Hippo.... This took me very long time to source out the problem because the scope of possibility cause this happen was huge... And I've read few forum about Skyline GTR, there are quite a lot number of owner also encounter this problem.

Here, I wanna make a summary of possibility to cause the idle stalling to your car.

INSPECT THIS FIRST:
1) Check your ECU, BOV and intake system. For those owner who still using stock ECU with MAF intake system, please don't change your stock BOV(recirculate type) to aftermarket BOV(blow to vent type) for better "hearing sense". After market BOV only recommend for aftermarket ECU and MAP intake system.


2) If your setup both are aftermarket ECU and BOV, then you can bring your car to workshop and ask them to check whether any air leaking(intake pipe, intercooler pipe, vacuum hose or maybe your BOV).


IF NO LEAKING, then all this below maybe cause idle stalling and you should :
1) Your AAC valve(some people call it "idle valve"), it maybe clog inside there and restrict the air. Ask the mechanic to take out the AAC valve and give it a clean. Then adjust the AAC screw back to normal RPM/idle speed.


2) TPS(Throttle position sensor), check the TPS voltage by using multi-meter, the TPS reading should be around 0.45V when throttle fully closed and around 4.5V when throttle fully open. If your TPS reading far from this, you can adjust it by turning the TPS clock/anti clockwise in order to achieve this reading. If fail, mean that your TPS is time to go and you need to change a new one~

3) Retune your ECU, by using this method. You can check your idle ignition timing and idle fueling pressure too.


By follow above solutions, this problem should be solved. Anyway, if problem still occur after you did all the steps at above, you need to:
1) Check your coil pack, coil relay and spark plug. Replace the stock coil to aftermarket product like OKD(best coil for me). Choose appropriate heat range of spark plug according to your driving style. Nismo suggest all Skyline GTR use heat range of "7".


2) Check O2 sensor, replace if necessary.


3) Fuel system, how long you never change your fuel filter? It maybe clog or leaking someway... Prefer to check the whole fuel system from fuel pump, fuel filter, fuel regulator, fuel rail to fuel injector.


4) Check all ground cable because a faulty ground will lead many problems.


5) Check your throttle body.

"My problem:
1) After engine warm, my car is very difficult to start, even I give some throttle when turning on the engine, it maybe stall after 3 to 5 seconds. Sometime no stalling but the car seems like very rough and RPM indicator is jumping.


2) My MFD screen show the throttle reading NOT 0% when idle.


3) Car occasionally stall after decelerate for cornering and stop at traffic light. Imagine the engine die when you around the corner.... *kencing also keluar*


Solution for my case:
Its took me very long time to overcome this problem....
- Change coil relay, coil plug and spark plug. (make my car run a bit smooth but still stalling...)
- Change new TPS. (solved my problem "2" but still stalling...)
- Change fuel pump, fuel filter and injector together with retune ECU. (because I plan for future upgrade while hoping problem can be solved after retune, but still stalling...)
- Check all ground cable. (nothing wrong to my ground cable)
- Check AAC valve. Due to is quite a massive job to take out a small AAC unit under the throttle body. we try to adjust the AAC screw to see how the car running before take out the unit for inspect. As the result, car is running smooth and never stall after adjust the AAC valve screw. (finally problem solve!)"

Hopefully you don't have this problem....