Skyline Idelling Hi And Low

[scott666]

Hi, sorry if I posted this in the wrong section, I also used the search button but came up with nothing.

So when my 33 idels at traffic lights or where ever the revs start going crazy, goes down real low to properly around 500 rpm all the way up to properly 3000-3500 rpm, as soon as I take off and drive the car is fine again.

Any ideas?

[BoyWhoCriedWolf]

Sounds like a vac leak. Check your ic piping. Do you have an aftermarket bov fitted? Could be leaking at idle.

[scott666]

If it was boost related I would of thought it would carry on under load. I will take ur advice and still check all cooler pipes attached properly.

[BoyWhoCriedWolf]

Do you have an aftermarket bov?

[scott666]

Yeh, its mounted on the cooler piping.. The standard bov hole near the throttle body is plugged up.

[mad082]

2 things,

1: may possibly be the IAC valve. this often causes a fluctuating idle.

2: the ideal location for a BOV is where the stock one is located.

also, was the plumback pipe blocked up? it should also be noted that RB's don't like atmospheric BOVs that much. it usually tends to make them misbehave when you lift off due to the ecu dumping a heap of fuel in. this may be part of your problem. if you have the stock bov then put that back on and block off the aftermarket one. see if that solves the problem.