Won't idle unless MAS is unplugged

[justinh722]

Just got done doing a 6 bolt swap in my 95 GST. I can get the car to start if I press the gas while the MAS is plugged in. It runs great above 1500 rpms. It wont idle at all unless the MAS is unplugged. I verified that the ISC is good through an ohm test and I adjusted the TPS to about .49 volts. When the MAS is unplugged, it will idle around 900 rpm but won't go any higher with the BISS screw adjustment.

Here's a small log I did while idling and revving the motor a little. The motor dies when the MAS is plugged back in. Desperate need of help. Thanks.

 

[liljaywizzle85]

My 90 TSI was doing the same thing. I replaced the MAS, and it just fine now.

 

[LiquidX]

~Front o2 is NOT cycling (P0135 code). Needs replaced.
~TPS should be set at 0.63v not 0.49v
~ICSPos should be at a 30 at idle. You cannot just turn the BISS to set your idle.
~Idle is set for 750rpm but you are trying to change it higher without changing the settings in Link.
~You have DTC codes (P0135, P0110, P0100).
First try ensuring the connector is fully seated and clean the MAF with MAF cleaner. If not working still then the MAF could be bad.
~Profile is NOT filled out to verify fuel.
~Uncheck "cylinder misfire" under the DTC tab.

 

[XiKeiyaZI]

~Front o2 is NOT cycling (P0135 code). Needs replaced.
~TPS should be set at 0.63v not 0.49v
~ICSPos should be at a 30 at idle. You cannot just turn the BISS to set your idle.
~Idle is set for 750rpm but you are trying to change it higher without changing the settings in Link.
~You have DTC codes (P0135, P0110, P0100).
First try ensuring the connector is fully seated and clean the MAF with MAF cleaner. If not working still then the MAF could be bad.
~Profile is NOT filled out to verify fuel.
~Uncheck "cylinder misfire" under the DTC tab.

^ This should help clarify your issues without a doubt. Sounds like a fight between your ECU, what Link wants your car to do, a few sensor failures, and what you're trying to force the engine to do.

 

[97gst_spyder]

Do what LiQUiDx said, and also, check the ground on the MAF. I had an issue like this it was a shot ground in the maf harness. It took out the mdp also.

 

[justinh722]

Over on ECMlink I was told to do some settings with the MAS by switching it to 2G hacked. I was able to get the car to idle at around 1100. The codes were there because I ran the car with the MAF unplugged and the front O2 was also unplugged. I cleared all the codes. For some reason the 02 doesn't cycle like it should. I will update my profile but as of now I'm running PTE 1200's and a walbro 255 and AFPR with a 16g. I was able to do a run and log it. Here's a more thorough log if anyone would be so kind to take a look.

I'm not sure if I'm running rich or lean or what these all mean. My dead time is at 500 and the duty cycle at -60. I was told on ecmlink to keep upping the dead time to get the O2 to cycle better but I hit 500 and still don't seem right. The log was over 600kb but I couldn't figure out how to crop the log any farther than what was showing on the screen.

 

[Alex7747]

Do what LiQUiDx said, and also, check the ground on the MAF. I had an issue like this it was a shot ground in the maf harness. It took out the mdp also.

Where would we ground the maf? Is it grounded to the car already? Do you have any pictures or threads that explain how to ground the maf? Thanks..ps. My maf needed to be grounded

 

[97gst_spyder]

IIRC, its the black wire on the maf plug. It goes to the ecu.