possible vacuum leak
 

Ok so i got my car all done and on the road ect, running good with a high idle of about 900 but i was fine with it. The first day of really driving the car during a hard pull (13psi) i let off the throttle and started coasting and my idle was sticking up around 1800 rpm :vash:. I have checked over all the vac lines and intake gaskets and all i found was my boost controller was leaking a bit so i removed it and it dropped to about 1650rpm but its still way to high. Where should i be looking for leaks ect? Also since that happened now when im just cruising and let off the throttle and let it coast in gear or down shit my afr's go right to 21.9 So im guessing when i let off the throttle its sucking in a tonne of air from somewhere?? I did a good long log to see if it was in the tune but i'm still having the same problem. Also before and after i did the retune randomly while driving sometimes the car will idle right at 750rpm. Sometimes it stays like that and sometimes it will slowly rise back up after a min or so. I'v been playing with it for 2 days now with no results. Also my vac and 1650-1800 is about 20. Any help or ideas is greatly appreciated. Also would my datalog be any help to anyone?

possibly move to tuning section?:noob:

Do a boost leak test, you'll get your answer quickly.

That does not sound like a vac leak really.

Often ECUs will basically provide 0 fuel under a coast-down condition, as there is not really any load. That 21.9 is likely about as lean as your WB02 can read, and I would not worry about it as long as it tends to cycle around stoich (14.7:1) in normal cruising conditions and get right where you want it under decent loads and boost. I am not really familiar with MS, but my guess is that this is exactly whats happening, which is good. I do know that you can adjust this behavior in MS, it was covered in a thread here late last year IIRC.

The idle issue may be a sensor type of deal.

I have yet to find the situation where a pressure test is a bad idea, and you certanly should do one. One thing that still shocks me about this community is the rarity of seeing someone post 'I just did a boost leak test and buttoned her up...'

But I doubt that is your problem. My bet is settings in the MS, a TPS cailbration issue, or something along those lines. The MS forum is you best bet for sure.

Are you MAF or MAP based? Also, make sure your throttle cable isn't too tight / sticking.

so just test the intake pipes from the turbo to the intake? turbo set-ups are new to me :facepalm:

At least you are asking in a post instead of starting a thread just for that question.

Do a search on google for way more info than you need.

A good pic of a home-brew tester like I use is here:

Boost leak test how to with boostpro.net tester - DSM Forums

The pic above "Step 3" shows it.

You pressurize the pipes, as you said, from turbo to cylinder head by use of a little clamp-on device. You really dont need a guage on it since you have a boost guage in the car.

With the pipes pressurized you can listen and feel for leaks. Just be sure you have everything secure. I have nearly lost eyes and other parts of my anatomy this way.

Are you sure you have a 14'G' turbo? The stockers from 1G DSMs are 14B turbos.

okay thanks man il deff try it, wow sorry spelling mistake ya 14b

well another issue fixed by this forum :makeout: actually was a vac line coming out of the lower rear intake?? had tape on it from painting the intake manifold :facepalm: guess when i hit 14 it finally had enough and blew off

Good to know I was wrong. I love vac leaks. Such easy to fix, so nice when everything behaves properly afterward......