[The Ghost]

Originally Posted by themyst

Makes me believe there is a bug in the AFR calculation. It's no coincidence a large group of people are having the same issue at once.

It believe the AFR reading is correct. The trim flatlines, then AFR shoots up, car loses power, and then I let off. I think there is some condition (caused by tune) that causes the DME to not add fuel trims.

[themyst]

Originally Posted by The Ghost

It believe the AFR reading is correct. The trim flatlines, then AFR shoots up, car loses power, and then I let off. I think there is some condition (caused by tune) that causes the DME to not add fuel trims.

How piggybacks add fuel is to report a leaner lambda to the DME (aka o2 biasing). The issue with this approach is that if you try to add too much, the car will limp due to the perceived lean condition sent out by the piggyback. That limp is the ceiling piggybacks have to deal with fuel limits.

What BMS is doing with the Cobb base flash and Vishnu with their base flash, is to proactively target the correct AFR/scalar instead of having to bump up against this DME limit.

Historically, pump gas with methanol injection proved to be more than adequate for stock turbos with the piggyback fuel approach, however with the new E85 craze, the DME is operating closer to those limits due to the increased flow requirements of E85 thus forcing BMS/Vishnu to stack piggyback with a base flash.

[jpirelli]

Got an update on this? Same problem here

[deploytosave]

Had identical issues here

As odd as this sounds (trust me I know it sounds stupid)

Take the car into redline in 2nd... Before shifting to 3rd... Seriously, it solved this same issue for me

[uniter]

Holy bump... What was the fix for these cars? I'm running into the same problems. Maxed +34% fuel trims OL set to 100% and I'm not running any e85 at all. In fact I installed an inline pump hoping it would help. No change. Firmware / maps recently reflashed with no change.
Is this a dying hpfp? Injector?

[GeorgiaTech335coupe]

Originally Posted by uniter

Holy bump... What was the fix for these cars? I'm running into the same problems. Maxed +34% fuel trims OL set to 100% and I'm not running any e85 at all. In fact I installed an inline pump hoping it would help. No change. Firmware / maps recently reflashed with no change.
Is this a dying hpfp? Injector?

My car would flat line fuel trims a lot more often when my OL setting was too high. If I kept it under 95 or so, it would not happen nearly as often. At 100% it happened a lot.

This was a long time ago though. May have been fixed, or maybe it's something inherent to the DME. Not really sure. I was never able to confirm this 100%, but it seemed like the problem/solution.

[B335T E92]

Originally Posted by uniter

Holy bump... What was the fix for these cars? I'm running into the same problems. Maxed +34% fuel trims OL set to 100% and I'm not running any e85 at all. In fact I installed an inline pump hoping it would help. No change. Firmware / maps recently reflashed with no change.
Is this a dying hpfp? Injector?

Bump. @uniter, same problems here. Did you ever figure it out -- I've upgraded to fuel it stage 2, replaced plugs, could, multiple sensors, added a backend flash. Please let me know.

[Kallibrated]

Also curious about the solution.

[GODDSPD]

Bumping an old thread because I’m having the same issue. Bank 1 trims occasionally flatline at 0 under mid throttle causing lean condition then it recovers seconds later. Anybody find the solution?

[mang.vang]

Bump

[d8rknight]

bump... having same issue now.. any update?

[Xcelsior]

My fuel trims are maxed out but I have no codes. The car idles rough and gets worse when I turn on the AC. Also have a loss of power but can still drive around town, just takes a little longer to get up to speed. I have tried the following:
Spark plugs
Coils
Reset adaptations
Replaced 4 O2 sensors
MAF and MAP sensors
Ignition Coils

Not sure what else to do. The exhaust note sounds a little different, kind of fluttery. Could an exhaust leak cause this?