so im getting practicly no ST Trim loss, but bank 1 is throwing 17% LT trim loss..

any ideas why?

 

....?

 

ST is short term fuel trim, LT is long term, so even 1% ST, will add up in the long terms

 

Are you saying the driver's side long term is -17%? I didn't even know they could go that low.... that would represent a BLM of 106. What Cell is that in? Or is that the weighted average of all Cells? What does the passenger side look like?

In any case, the PCM seems to feel the driver's side is running excessively rich, and is pulling out 17% from the standard fuel calculation, in an attempt to lean it out. You have to figure out whether its a "true" rich condition, or if its a "false" rich condition.

You might want to add a "signature" with basic info.... year of the car, tranny type, any major mods.

 

Suspension, Jet hot LTs, x pipe w/ mags dumped before axle, TB bypass, descreen maf, Moroso CAI, NGK tr56 plugs, taylor 8mm OVC wire kit..

bank two is fine, i think it was almost perfect.. but bank 1 is throwing -17%

Could it be a bad o2?

Why would it be the lt trim to pull that much if it really thinks its THAT rich.. while my st trim is optimal

 

The system starts at a "neutral" balance of 128 for both ST's and LT's (= 0% correction to the PCM fuel calculation). In normal fuel control, the PCM intentionally cycles the short terms from slightly rich to slightly lean. That helps the cat work. While the ST's are moving above and below the neutral value of 128, as long as the AVERAGE ST is 128, the system is in balance.

The system goes rich, and the PCM has to start pulling out fuel with the ST's. If it sees that the ST's are running at an average value that is well below 128, it pulls the LT down, in the hopes of getting the ST's back to an average of 128.

If it continues to run rich, the ST's will stay below an average of 128, and the PCM will keep dropping the LT's to lean it out permanently. When the LT reaches the value that keeps the system at the design A/F ratio, the ST's will be back at an AVERAGE value of 128, meaning all the correction is being done with the LT's, and the ST's are being used to dither the A/F ratio and keep the cat(s) working.

 

i have no cats for one

for two could it be the o2 sensor on that side is bad? the other side is reading pretty optimal, and that o2 had been replaced recently, as oppose to teh bank 1 side which is causing problems and has not been replaced