My Car Stalls After Boosting - Also Runs Rich

[2ndgendsm-md]

Ok I just bought my 98 gst a month ago and I have been having issues after I build up boost and then try to idle. After a decent pull building up even a moderate amount of boost pressure, if I shift to neutral to try and idle (say at a light) my car will just stall. I can adjust the biss screw to compensate for this, however, I would like to fix the problem, not drive around idleing at 1700 rpms. My setup is in my profile, basically stock motor and fuel setup, mhi e316g, greddy front mount (the 24v i think, dunno it came with the car) and recirculating greddy bov. Also i've noticed a decrease in gas mileage, and the all too familiar smell of running really rich. I have searched and read a few posts from people with similar problems, my injectors and seals are not leaking, im not 100% sure but I don't think I have a boost leak, I could be wrong though. My only guess is that I have a leak somewhere in my charge pipes or the intake manifold or throttle body. I do have access to a leak tester, I was just wondering if anyone has had a similar problem so I can narrow it down. I am also not sure if the previous owner upgraded the fuel pump or not, would these symptoms be similar to what would happen if the pump was overrunning the fpr ? Im leaning towards leak, seeing as this car leaks everything that is a liquid and a gas, im waiting for the solids (It is a 7 bolt). Any help would be appreciated, I am sick of diagnosing problems on my car almost every other day,

 

[weldtuner]

I would start by visually inspecting everything after the car warms up. If you don't find anything then do a boost leak testhttp://www.dsmtuners.com/forums/articles-turbo-system-intercooler/169435-boost-leak-test-how-boostpro-net-tester.html This should give an idea of how to do the test, also you don't need the fancy tester, just make one with some pvc and gauge/fittings.

 

[darkhorizon]

I vote boost leak. Its tough for your car to run at idle without dead nuts on fuel calculations.

 

[2ndgendsm-md]

I also read somewhere on here when I was searching that a guy bought a gasket set for his throttle body and the valves/sensors on it, but now I can't find it - anyone read this before ?

 

[DougR]

idle speed controller will fix both you idle and rich condition, might need a new front o2 sensor also.

 

[JMiller]

I say do a boost leak test, quick, easy and may fix your problem.

 

[mentalTSiAWD]

I'll definitely vote for the boost leak especially if you have access to a tester. But it also sounds like you might need a new ISC. Sometimes you can take it off, clean it and reinstall and be good to go. Be careful messing around with the BISS. You can give yourself some real headaches.

 

[dsm1212]

+1 boost leak if it only does it after boosting then its probably leaking the air somewhere so there will be more fuel

 

[wangboy925]

I had a similar problem and it turned out to be a loose wire coming off of the throttle body. It's hard to explain but its on the very top near the 4 vac ports for your emissions.

 

[2ndgendsm-md]

did a leak test today, my compressor/charge pipe/intercooler system is not leaking, so i tested the throttle body and intake mani - the biss screw, the throttle position sensor and the other side where the cables attach, and the idle controller on the bottom of the throttle body are all leaking. so basically I need a new throttle body or a gasket set. Pretty much everything on my throttle body is leaking air...

 

[dsm1212]

well glad you found it now just get that fixed up and get boostin