relacing parts, still not fixed

[san rensho]

Check for a vacuum leak in the evap system and the auxialary air injection system. Very hard to diagnose so don't start throwing parts at it because you can easily spend thousands without finding the problem


First thing is to use a durametric to make sure you have a vacuum leak. If the maf spec is significantly below spec, 15, then you probably have a vacuum leak.

[1boxsterjim]

Originally Posted by san rensho

Check for a vacuum leak in the evap system and the auxialary air injection system. Very hard to diagnose so don't start throwing parts at it because you can easily spend thousands without finding the problem


First thing is to use a durametric to make sure you have a vacuum leak. If the maf spec is significantly below spec, 15, then you probably have a vacuum leak.

Any thoughts on the N/A and 99.2 %?

[Jamesp]

I found a super way to find a vacuum leak, or completely rule one out while trouble shooting a SAI problem. It's a bit involved, but bullet proof.

First roll the engine to TDC. (That's the first part of involved)

Then pull the plastic intake tube off the throttle body and slip a 3 mil piece of plastic between the tube and throttle body, put the tube back on the throttle body (the second part of involved)

Pull a vacuum hose off the intake manifold and blow into it. The manifold should hold air. It should feel like you are trying to blow up a hot water bottle. When you release the air, it should blow back out the hose. Holding my finger over the hose, my intake held pressure for about two minutes. Pretty impressive.

If your manifold leaks down, it's time for a cheap cigar. Light the cigar, take a deep drag (don't inhale though!), and blow that lovely smoke into the intake manifold. Doing this in the dark with a flashlight to find the smoke leaking out works well. Small as the leak was, I saw a tiny bit of smoke coming from the valve in the resonance tube

This also works on the lower end using the oil fill tube, electrical tape, and the corner of a 3 mil trash bag (dipstick tube might work as well, I didn't actually use that).

Best of luck.

[.Jack.]

Originally Posted by Jamesp

I found a super way to find a vacuum leak, or completely rule one out while trouble shooting a SAI problem. It's a bit involved, but bullet proof.

First roll the engine to TDC. (That's the first part of involved)

Then pull the plastic intake tube off the throttle body and slip a 3 mil piece of plastic between the tube and throttle body, put the tube back on the throttle body (the second part of involved)

Pull a vacuum hose off the intake manifold and blow into it. The manifold should hold air. It should feel like you are trying to blow up a hot water bottle. When you release the air, it should blow back out the hose. Holding my finger over the hose, my intake held pressure for about two minutes. Pretty impressive.

If your manifold leaks down, it's time for a cheap cigar. Light the cigar, take a deep drag (don't inhale though!), and blow that lovely smoke into the intake manifold. Doing this in the dark with a flashlight to find the smoke leaking out works well. Small as the leak was, I saw a tiny bit of smoke coming from the valve in the resonance tube

This also works on the lower end using the oil fill tube, electrical tape, and the corner of a 3 mil trash bag (dipstick tube might work as well, I didn't actually use that).

Best of luck.

I agree but please use a decent cigar. It is a Porsche after all.