I just installed a new turbo kit and now I am having very high idle/cruise afr. Once I boost the car, the afr swings into the normal range. Until then it seems to hover around 20. Any ideas on what would cause such high closed loop afr? A bad O2 sensor? Exhaust leak? I am having issue logging afr with evoscan right now but am logging fuel trim and injector duty cycle. Also the my methanol is kicking and it is IDC based. I have no signs of knock or trouble codes so far. Thank you for your help.

 

I reflashed the car with an old flash and disconnected the battery. The car is still displaying an extremely high afr at idle/cruise. My idc seems normal and afr goes to normal values once I enter boost. Any suggestions?

 

High meaning lean? how does your fuel trim look?

 

Yes, the wide band says that ---20%O2 which is basically off its scale. When I enter boost it falls into the 11-12:1 afr and when the meth hits it falls to 10:1 or so. I have not attempted to tune the afr yet. I am going to try and recalibrate it. My fuel trims seem to be ok. So far low LTFT seems to be around 4% to 7% and the mid/high LTFT are +/- 1% so far. I have to take a long drive to plano and back so I am going to do some more logging.

I have brought my injector duty cycle up to about 40%-50%. I am only running about 20psi right now while trying to sort this out. I am not seeing any knock.

 

Ok so I recalibrated the wideband and now it is saying 19:1 / 20:1 at idle. This is better than what it was before. I am going to drive to Plano and log more trims, see how it does at cruise.

 

I would guess an exhaust leak is the cause of your wideband issues. At that AFR your car would stumble something fierce and probably die, assuming it runs ok a leak is most likely candidate here.

 

My vote too.

 

Thanks I will order a set of new gasket and possibly a new v-band clamp.