I have a 2001 Subaru WRX with a 2.0 motor and aftermarket Garrett turbo. Engine very rich. Help!?

Question

Recently purchased a 2001 Subaru WRX with a check engine light on for a good deal. It runs very rich with black smoke out tailpipe and I can hear the engine missfire and sometimes popping. The engine is a 2.0 with a Garrett turbo and large intercooler. Engine actually runs better with main vac line removed. I can't hear the turbo spool up at all but when removing the air intake tube you can see the small propeller moving. There are about 8 codes that show; no surprise and the catalytic converter is gone. there are 2 small leaks in the exhaust right behind the turbo, too. Thank-you for your help.

Answer 1

When the turbo was installed, nobody told the PCM about it.
A turbo will radically change the parameters of a host of sensors, including the MAP, MAF, O2 etc.
Check with the manufacturer of the KIT, not just the turbo, and ask if there are modified sensors or computer programming necessary for the turbo.
The reason the engine runs better without the vacuum hose is because you have effectively lowered the manifold pressure. The computer uses sensors to tell it how hard the engine is working, and at what speed and load. The turbo alters the conditions and if the sensors report this kind of change, it will change the fuel delivery and ignition curve.

Hope this gives you a bit of direction.

As far as your codes go, you can go here for descriptions, and use a repair manual for diagnostic and repair routines.------>

http://www.obd-codes.com/trouble_codes/index.php

Good Luck

Answer 2

Looks like you've taken over a botched project. There may very well be a few other mods on there you haven't listed - I suspect he may have used an aftermarket fuel pressure regulator and set it too high, or installed larger injectors and did not make any changes to the computer. Either of those can make it run rich.