Hey guys!

My 2000 Blazer it's equipped with the L35 4.3 Vortec, and I was looking trough a cheap OBDII Bluetooth reader i checked the fuel trims and they are mostly stuck on -18%, on both banks, (short trim goes +5 and sometimes even -30%, so I think to PCM can correct itself)

Sometimes i can smell the rotten smell from the exhaust, I have replaced the FPR and the poppet injectors where refurbished.

That MAF, MAP, coolant temp sender and IAT appears to be working prorperly. And the O2 sensors are going up and down the way they should be.

No codes are present, but i'm concerned about the rich conditon because of fuel economy.

I live in Brazil and here the gas is E27 mandatory, that would richen the mixture?

I appreciate any help.

 

I would expect E27 to cause positive fuel trims, not negative. PCM would have to add additional fuel to do same thing since EtOH does not contain as many BTU's /gal as gasoline and this would manifest as a positive fuel trim.

Maybe you have a poppet injector dribbling fuel or pressure regulator leaking a little. Upgrade MPFI injectors are available. Did anything change when you installed the new FPR and poppet injectors?

Maybe capture a log of the upstream O2 sensor voltages while you are driving for some time. Put the vehicle speed and engine RPM in the log as well so you can tell what you were doing. As long as O2 sensor voltages are cycling and crossing 0.45v, the system is controlling the fuel mix and is happy. Take note if one sensor changes a lot and the other one doesn't. What scanner are you using? Also you can just plot the voltages, but you will need to watch the plot happen instead of driving.