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Car is running rich

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99gst214

10+ Year Contributor
246
2
Apr 24, 2009
Champaign, Illinois
I just purchased a 1999 GST. I am new to the DSM world. The car has been running very rich ever since i brought it home. The only upgrades the vehicle has is an Injen intake, an Apexi catback, and an Apexi S-AFC 2. The only code which the vehicle has thrown is a P0100, which is for the MAF sensor. The previous owner says that a new MAF sensor was just installed right before i got the car and it tested fine. Also another related problem is that under wide open throttle condittions the car wants to cut out from 1800-2800 rpms. The TPS may be bad. When testing it, it fell well short on a resistence test, but i just wanted to make sure it wasnt just a fuel issue before replacing it. The fuel pump is quite loud and can be heard running constantly, dont know if that is an issue or not? Is there a base line fuel set-up for the S-AFC 2 that has worked well for anyone with a stock 2G GST? Any advice is much appreciated!!! Thanks!!!
 
OK i have done some research already on the SAFC, with "alldata". It wasnt as in depth, but it got me familiar with the way to set and tune with it. The SAFC wasnt set up right when it was installed so i set it up again and began taking fuel out from the lower rpm range. Still the car has the WOT cut and still looks like a 12v Cummins. LoL, not that rich. But it seemed to make very little difference after using the SAFC properly. Wut to do? Do i continue to take more fuel out or should i look toward replacing the MAF or TPS????
 
Yes the fuel pump is stock and you can here it "buzzing" even outside the car. should i replace it? Could the fuel pump be loading up and causing the car to run rich?
 
Yes the fuel pump is stock and you can here it "buzzing" even outside the car. should i replace it? Could the fuel pump be loading up and causing the car to run rich?

aftermarket pumps bought from local parts stores commonly make alot of noise this is normal. If your getting a MAF code this is the issue. The MAF tells the ECU how much air is being pulled into the motor figures barometric pressure and a few other things> Basically if the MAF is reading X amount of air then the ECU is compensating with X amount of fuel. If the car is running that rich start with a Boost Leak Test.

If its pre turbo theres your MAF code. If the MAF doesnt look new hit me up. Ill ship you my extra 2g for $15 It needs silicone around the top where it was removed and inspected but it still works great. I can post pics if necessary its kinda just taking up space


Kolby
 
Tell me about it I thought it was bad so I went to pick a part It was in a car turned upside down I had to dig for it and it still cost me $75 I brought it home installed it and same results... So I put on a 3rd one from a friends car same readings. So I have 2 good MAFs and one car. LOL

My problem was a massive boost leak near the EGR and throttle body... so $15 is worth my time to box it up + shipping. I dont see it being more than about $25 to any of the 48

Kolby
 
Well let me take a more in depth look under the hood and see what i can find out. Is the WOT cut out just from too much fuel or would that be the TPS? Like i said earlier, when doing a resistance test the TPS fell way short.
 
You said the error code was for the MAF sensor... Why dont you replace that FIRST. Considering if the MAF is bad, it isnt bringing in the right amount of air. So the car is going to run rich and put out black smoke. My car was doing the samething, till i dropped a used MAF in.... Now its good to go :thumb:
 
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