Running Rich 3" GM MAFT2 S-AFC

[hornetracer8]

I have been fighting this for 2 weeks now. And I have read about every thread I can find.

Please Help!!

Always RICH!!!!!!!!!

I have a 98 gst I just bought. Fresh rebuild 9:1 comp, Forged lower end. 650 injectors AFPR set at 36 PSI Base.

I have a S-AFC leaned out all the way -50% High and low.

My MAF Translator is also leaned out all the way -35%. Mode switch first 2 switches off #3 on #4 off. I also read if you set the AUX and BASE for a larger injector size it will lean out that also tried that didn't help.

My O2 voltage varies from 0.880 and .960 on my scan tool. When at idle. And if I rev up the motor the O2 does up to .990 and starts breaking up. Black smoke and plug are fouled Black.I have a new O2 sensor, No boost or vaccum leaks.

Any Ideas would help.
Thanks
Coolant sensor reads fine on the scan tool 197 to 212 when warmed up reads fine when cold also

 

[hornetracer8]

I also dropped my fuel pressure to 25psi to see if it would lean out. It did not help very much

 

[hornetracer8]

I just tried to use the safc to see if it is hooked up right. I moved all the settings from -50% to 0% Just to see if it would richen up, and it did. The O2 sesor maxed out on the scan tool 1.0v. So i moved it back to -50% and it leaned out to .900v still way to rich.

Anything Please???

 

[bmwisthekey]

so u are compensating for the 650cc with the maft right? what do u have your base knob set to? being that your a 2g, your aux knob should be on 5, and base on 7 for 650cc injectors, is that correct on your translator?

 

[hornetracer8]

Yes that is where they are set.

I even tried to set it for a larger injector like Aux 6 Base 2 Still didn't help.

Am i suppose to have the key on and engine off when i change the settings?

I always unhook the battery to rest the ecu after a change to the maft.

 

[hornetracer8]

I noticed my short and long term fuel are both at 0 on my scann tool. Why is that??

 

[44pirate]

Do you have the GM MAF in the stock position, and is it in facing the right direction? Screened or non screened? Are you recirculating?

 

[hornetracer8]

The MAF is in the upper hard pipe. The arrow is pointing to the throttle body It has a screen. And I have a hsk BOV.

 

[hornetracer8]

Can anyone else turn me in the right direction?


Thanks

 

[absolute_DSM]

Boost leaks, pre turbo exhaust leaks.

Youve got something set wrong or a good sized leak before your O2. Are you even sure your O2 sensor is good?

 

[hornetracer8]

O2 sensor is good. brand new the old one read lean all the time very low voltage.

I have done a boost leak test that is not my problem. All Gaskets are good no exhaust leaks.

If somthing is set wrong i don't know what it would be. All my maft settings are right where they should be and my safc is maxed to -50%.

 

[spoolintsi97]

I had that problem and i set my translator to run with a 3.5 inch gm maf and it has worked great ever since. Also I had the same problem with my LTFT turned out to be a faulty barometric signal in the translator, checked it with a voltmeter so what i did was take a AC delco barometric sensor and wired it in and installed it in the intake pipe and it works well.

 

[hornetracer8]

I had that problem and i set my translator to run with a 3.5 inch gm maf and it has worked great ever since. Also I had the same problem with my LTFT turned out to be a faulty barometric signal in the translator, checked it with a voltmeter so what i did was take a AC delco barometric sensor and wired it in and installed it in the intake pipe and it works well.

How did you wire the AC Delco baro sensor in?
Also is having a faulty baro signal a big problem with dsm's or is it just you and me?

 

[spoolintsi97]

The senser has three wires a 5 volt, ground, and a signal I hooked them up to the the maf sensor harness accordingly. Anyway the problem is not with our cars it is with the translator unit. If you read the manual that comes with the translator it says that the baro voltage should be fixed at 3.9 volts and mine read .003. First try the 3.5 maf set-up for 650s that should work. I remember when i changed mine from 3 inch to 3.5 inch my STFTs and LTFT combined went from +32 to -20 and i then tuned from their.

 

[hornetracer8]

Thanks I will try that. I noticed my baro volts were always around 3.9v. Alright I have some hope again.

Thanks for the info I'll let you know if it works.
Brandon

 

[spoolintsi97]

Just zero the AFC out and set the translator to 650s before you change it to 3.5 maft. These should get you close but you will have to fine tune with some sort of logger. Also it sounds like your baro signal is fine because i would get a cel. Good Luck

 

[hornetracer8]

Just so i know for sure.

When changing the settings on the maft should the car be on or off and sould the key be on or off.

I know when making changes to the mode switches the car must be off and you must rest the ecm.

 

[bmwisthekey]

im pretty sure the car should be off and key off when changing the base settings , as well as mode switches, and a battery reset when changing those too

as for the idle, mid, wot changes u can do that with the car running.