Having idle issues. I did a boost leak test and found a line off of the intake manifold. Put that back on and it still idles at -10, and now when I boost leak test it, it holds the pressure fine. When im driving and just let my foot off the gas itll drop to -22, but as soon as I push the clutch in it goes back to -10, and same at a complete stop.

Any ideas?

 

did it idle with more vacuum than that before? if you have cams that isnt too far from normal depending on how aggressive they are.. -10 is about what i get at idle with m3's

 

Every car isn't exactly the same...a lot of factors can cause this to vary. -10 is fine unless it was at something else previously and suddenly changed.

 

Only mods are intake, evo 9 turbo, exhaust, and apexi boost controller. No cams. And it was at -20 before. It sounds like it has cams, but it never did before. Maybe someone swapped me out some cams last night

 

That seems normal for idle. I would zip tie all boost lines and then drive straight to the tuner. Make sure to stay out of boost because the Evo 9 turbo is a bigger turbo and the extra airflow will be bad for an untuned Evo.

 

It has already been tuned. Was tuned by the previous owner when he put the 9 turbo on. And now it just randomly stalled at a stoplight. Its definitely different than it used to be, I know for a fact it idled at -20 if not lower and now its at -10 if im lucky. Any chance it's the IAC valve?

 

did your idle RPM change?

 

It dropped about 200rpm

 

When the car is off does the boost guage read 0 or does it read something else? And there is a reason I am asking.

 

A low idle will show lowered vacuum. the gauge didn't go bad at the same time the idle dropped. Check the vacuum lines, intercooler piping, etc. suddenly running funky, lowered idle, lower than normal vacuum, clear signs of a boost/vac leak.

 

Yes, gauge reads 0. Ill do another boost leak test. It held pressure fine when I checked it yesterday, much better than my z which has no idle issues.

Ill update with results then, Thanks

 

Interesting, check for sensors coming unplugged. I, for one, almost never retain the little metal clip that holds the plugs on, so this is sometimes an issue for me.

 

Do a compression test on the engine. If it sounds like its camming now and didn't before, and has lower vacuum than it did before, look to a base engine issue.

 

check the timming marks all are were there supose to be i had tensioners go bad and loose my timing which gave me low vaccum and crap idle also changed the exhaust note a bit

 

I forgot I didn't update this thread. It ended up being a bad tensioner which made it jump two teeth. I ended up just doing the full 120k mile kit. It's back to normal now. The timing belt took a lot longer than I thought it would to replace though lol. Much longer than any other I've done.

Thanks for the help guys!