Im trying to tune my car for my turbo setup. I have a cross over pipe from the passneger side to the driverside, through a log and then to the turbo. My wideband is in my down pipe after the turbo, the two O2s the pcm uses are in the cross over pipe, so they are basically both reading the same bank.

I normally run my car in open loop, but for this tuning I have been trying to use closed loop, problem is my computer thinks the car is way rich and pulls fuel, to the point where the car is barely drivable. This is all part throttle problems, when I step on it it richens right up. Runs fine in open loop, and I put my wideband in the cross over and it reads pretty much the same as having it in the down pipe.

I am new to tunning, and Im using the tune for my cam as a base. Im sure this is a really basic question, but is there someplace that tell what a/f the car needs to shoot for. I dont see why It thinks the car is lean, these are new O2 sensors and I know they are good b/c the car runs fine on emissions day when I put my OBDII computer in. I take them out and put some old ones in otherwise.

What tables should I look at in LT1 edit to tell the computer to look for a richer a/f?

 

Wow, this question was posed so long ago and you never got an answer. I had the same setup for the most part and the same results. I just removed both my brand new O2 sensors and stored them in a box with the two prior (still good) O2 sensors, plugged up the sensor bungs with appropriate bung plugs and have been driving around in Open Loop. I've modified my Open Loop A/F ratio tables to get the A/F to 13.x to 14.0 using my PIX O2 Wideband.

 

Hey thanks for the reply.... I ended up doing the same thing you did. My car is apart right now for a motor build and Im going to try and move the O2 sensors into the down pipe after the turbo to see if it helps.

I mostly just want to be able to use VE master to get my VE tables where they should be and then go back to open loop.

 

The O2 sensors work, in part by comparing the voltage generated on the surface of the thimble, with the voltage generated on the "inside" of the thimble, which is exposed to atmospheric air. The difference in voltage is used to add (rich mixture) or subtract (lean mixture) from the 450mV supplied by the PCM. With a turbo, exhaust back pressure would seem to increase appreciably. I wonder if the narrow band sensors are thrown off by the increased "partial pressure" of the O2 fraction of the exhaust?