Hello,

I am need of some assistance. Any help would be greatly appreciated.

First some info on the engine:

2.0L, Crane 16s, ported head, 10.5:1 comp pistons, new plugs, coil is good, wires are good, MAP sensor is good, coolant sensor is good, IAT is good, new EGR valve and stock engine management system.

For a while now (2-3 years) I have been fighting a rich condition on my car. Gas mileage is horrible and I am constantly getting a P0172 CEL code.

So, thanks to some fellow 2gnt'ers I recently purchased a Bluetooth OBD2 scanner which allowed me to view engine live data.

Almost every parameter I looked at seemed normal but these two: short term and long term fuel trim.

At idle (after warm up) my LTFT was sitting at -25% while my STFT was bouncing around between -4% and -15%. The O2 voltage pretty much bounce between .2V and .9V.

At normal cruising speed (2500-3500rpm) my LTFT was at -25% and my STFT was sitting around -7% and 0% (It seems like it got better). ONce again, the O2 voltage was bouncing around just as if it was at idle.

At WOT,or upon engine breaking (High vacuum), both STFT and LTFT parameters would go to zero percent.

I need some assistance interpreting this data. I can see that the ECU is trying to take fuel away (lean it out) at idle and at cruise, but I don't see why the LTFT doesn't fix itself once I am cruising around. What am I not understanding?

Also, I have theory: I believe that part of my problem at idle is because of the cams that I have; this is based on some research that I've done on neons.org. I am thinking that the ECU is thinking that there is more air in the engine than what there really is (this being due to the higher overlap because of the cams) or maybe there is not enough air in there and it can't pull anymore fuel? Would this be possible?

Any theories would be greatly appreciated. Right now my next course of action is going to be the installation of my SAFC2, attempt to lean out the idle, and some low rpm settings based off of my fuel trims. WOuld the SAFC be able to remove enough fuel and help with this issue?

Thank you all for your help,


Oscar

I wish I had blown it, believe me, I do...