maft tuning help o2 reading rich and wideband is lean

[supercarbuilder]

Ok, I have a 95 tsi with 6bolt, evo iii 16g, 650's, aeromotive regulator, walbaro 255, 3" gm maf used for blow through. Tried to tune and I can get it set and then it goes lean on the wideband, like of the chart and won't even read. I can keep adjusting the translator richer and it keeps adjusting leaner. The O2 voltage stays at 1275 mv. I thought when you get a bad O2 sensor that it reads 0. And I don't know how much the o2 reading can effect the ecu. You know, how much percent it can make the ecu adjust for. or is it indefinately? I need help and guidence. I don't want to get rid of this car but I have basically had everything on it break.
Also, I know I have a good translator and gm maf. thanks

 

[GVR4592]

I wouldn't pay much attention to the stock O2 sensor. If the wideband is working correctly, it's far more accurate than a narrowband unit. I would sell the gm maf/translator combo, go back to the stock maf and get an SAFC for tuning. It's a hell of a lot easier and a lot more accurate than the gm maf/translator combo.

If you want to keep the Gm maf then somebody else is going to have to help you out because I hate those damn things, they're more trouble than they're worth.

 

[turboglenn]

Test your wideband though. hold it in open air then hold a lighter to it. The yellow part of the flame should be right around 14.7:1.. The blue should be about 13.5:1 and holing it 1/4 inch above the lighters flame should produce around 19:1. Not a dead accurate lab style test, but enough to see if your WBo2 is WAY off or not.

And most of the time don't trust teh factory o2, they're junk!

 

[supercarbuilder]

but if it doesn't change from 1275 mv, does that mean that it is junk? And I'm thinking about doing the afc but I'd really like to see if I can get it to work because I think something else is going on that I'm not seeing.

 

[supercarbuilder]

And if the factory o2 is telling the ecu that it is way rich the ecu can continue to readjust leaner and that can be why my translator setting will not stay put?

 

[supercarbuilder]

No exhaust leaks anywhere. I've been doing some checking and i've got to this point......in an open loop at start up its not monitering o2 so it is fine. Then after a min or two it drops off lean because its moves to a closed loop and is reading what the o2 is telling it (1275 mv) so then it tries to lean out the motor because of it and the wideband says that it trails off lean. So lean that the wideband will not even register and it will barely run. I can tune the maft at idle as rich as it will go and the ecu still over powers lean. Then if I get the rpms up to wide open throttle it goes to an open loop the o2 will drop and the wideband will pick up readings again.

I also don't have the map sensor pluged in because of my 6 bolt swap. any sugestions? I was told you didn't need it but I think I'll tap it in to the booster line just because I'm stuck.

and I just tried a brand new o2 and it didn't change.

if this helps me get some answers that would be great! thanks

 

[DSMDirkah]

Try putting your 450cc injectors back in and set the MAFT accordingly. I thought that the MAFT would not be all that great either and I tried it and it worked for me. If you still have the same problems after you put the stock injectors in than it would probably be another issue other than the MAFT setup.

 

[turboglenn]

That's odd, I wonder what is causing your regular o2 to be reading so rich? Is it the stock one or did you recently replace it? I would say if this just started after the install of one of the parts you listed in teh post; i would undo whatever i changed to get it back to where it was running good. Then if all teh parts you took off seem to be in good order start re-installing them payng a bit closer attention to everything you hookup. confusing a wire pin on teh ECU is easy to do. Some are damn near the same color. Double check everything.

I bought a bosch universal o2 a week or so ago and it would read 1.274mv or something like that at anything over 14:1 on the WB and then anything lowe it went to about .124mv I just disabled teh closed loop untill the snow'a gone and i cna change the sensor and try a new one. I'd prefer a stock on just becasue it's got hte plug on it and it's an NGK i'm pretty sure ( i don't like bosch haha )

 

[supercarbuilder]

I'll try that, the o2 is oem with the plug. the only thing I can think of is when I installed the wideband maybe. trouble is that I did almost all my mods at once while I was waiting for stuff like the motor. maybe thats not such a good idea. thanks for the info.

 

[zatomz]

Can you call a local shop and see if anyone there has any knowledge of the maft. I have a gen II translator, AEM wideband and close to the same setup as you and to be honest I'm having the guys at polk performance tune it for me when I get everything put together. I just got everything installed in the car I haven't started it yet.

 

[supercarbuilder]

I'm looking around, I found one but they're kind of quick to swap parts. I used the main mechanic to tune it origionally.

I'm not looking to pay a shop $70/hr for 6 days just to tell me that they have to start replacing things to figure it out.

 

[supercarbuilder]

i got it now. there was a wire hooked to the o2 signal on the ecu that must have been feeding it voltage and then it thought it was rich.

thanks everyone for your input.