I have been getting codes that my Long Term Fuel Trim is too lean. According to my scans, it is showing a 25% all the time except on decelerations. But at the same time, my o2 voltages are in the .950v area which I thought was ok. This car was parked for a year since I was in Germany. Could this be a bad sensor? I am also having issues with my #2 knock sensor not giving sufficient input? Is this sensor bad? I would like to get these issue resolved before I start putting the new engine in.

 

your o2 sensors are quite obviously stuffed or you have wiring issues. around 500mv is stoich. If your O2 Voltage is staying at 950mV and not switching to low 050mV when in closed loop it confirms it. The car will be very lean. This correlates with your O2's thinking that its pig rich and removing heaps of fuel via your LTFT's. I wouldn't drive it like this if I were you

 

I meant that the 950mV was a WOT. Durinig normal driving, they do switch back and forth, but the LTFT seems to stay in the +20% range. I thought the computer is trying to add fuel. I had one tune in it last year that bellowed some black smoke during a dyno run. I thought the car was running too rich. I guess I will have to go back to that tune just to keep the motor running enough till I install the new one.

 

Check your MAF it may have carbon or debris on it. If so clean it with either brake clean or electrical cleaner and try it again.


Chris

 

Not really. The sensors is relatively new. It does matter much anymore. My Dart heads are in route and this motor is getting pulled soon. Thanks for the input guys