300guy

I've installed the rebuilt engine and it runs very smooth but it will not idle when it is cold.

With a little bit of pressure on the pedal, it will idle nicely - but if you take your foot off of the pedal is dies. When the car warms up a bit, it will idle o.k. and when the engine is fully warmed up it idles perfectly.

I'm thinking that it could be the idle air valve or the TPS or temperature sensor?

Am I on the right track? Any one else have a similar problem before?

300guy

My impression of the Fidanza flywheel is that the engine is certainly a lot more responsive, and there may be a few more ponies for acceleration.

The torque tube rattle is there... I don't like it. The clutch engagement is incredible. Precise and smooth, and much better than stock.

The dynamic balancing and S2 harmonic balancer make the engine very smooth. A noticeable difference over stock (as compared to a friends stock 968 that was right beside my car).

RajDatta

300, glad things are working out for you. Sounds like one hell of a car.
Usually a cold start point to idle stabilizer valve. Is it connected? They can gunk up over time.
Raj

300guy

is there any way to clean it or repair it? Or is replacement required?

Any way that I can apply power directly to verify functionality? Is it either on/off or is it veriable?

thanks Raj,
Colin

RajDatta

Colin, I have heard of people taking it apart and cleaning the gunk only to see it gunk up again. Its only on/off. As soon as your idle drops, the system should kick in and compensate.
Are all connections good? are all the hoses to and from ISV tight?
Raj

968workaholic

With the key in the On position you should be able to grab the Idle valve and feel it vibrating. It is not simply an on or off valve but ather a variable valve. It lets more air past the throttle plate when the engine is cold and less when it is hot. It does sound like it may not be plugged in, since it just dies at idle. Usually when they become gunked up the idle bcomes progressively worse, not suddenly it won't idle.

300guy

Thanks guys, I'll check some of these things out.... just need to find the time to work on the car!

300guy

With the key in the on position I can hear the auxiliary air valve buzzing. The hoses are firmly clamped. So it seems that the AAV is functioning.

What else could this be? TPS?

Is this problem indicative of a faulty MAF?

note that I have plugged the hose from the crank case breather tank that connects to the throttle body because I'm venting the breather tank to an aftermarket breather tank.

300guy

Ideas anyone?

968workaholic

I don't think it would be your MAF but it is possible since it sounds like your Idle control valve is working properly. The car wouldn't really run right if the MAF was faulty too. I don't think a faulty TPS would cause a no idle condition. Try taking the Idle valve off and spraying some Throttle body cleaner into it. It may have some crud in there. If it makes a difference, then you know the direction to go.

300guy

Good call... I'll try that.

Is there a possibility that the engine temperature sensor is bad? From what I understand, it is a different sensor than the one used for the temperature gauge.

A disconnected temperature sensor would result in infinite resistance - this would simulate a cold or hot condition?

968workaholic

It depends on the type sensor that Porsche used. Did you try to see if there were any codes stored? There might be something going on that tripped a code but didn't set a check engine light. Im not convinced that a bad temp. sensor would completly disable that idle when the engine is cold. I could see some affect but not a large one as you are describing.