[Raptor04]

Does a negative fuel trim result in not reaching boost targets? I am underboosting below 3K rpms, and above 4500 rpms. At the same time, my fuel trims go negative during this time? Can I adjust my fuel tables in these rpm ranges so that I reach boost targets, or is this simply a symptom of small turbos at high altitude....take longer to spool and run out of air up top?

[135Pats]

The DME is pulling out fuel, could be doing it for a variety of reasons but likely is being done to manage lambda. Do you have any logs? I don't see how negative trims would cause you to not hit target boost, but anythings possible and fueling is complicated.

[dlbrooks18]

Originally Posted by Raptor001

Does a negative fuel trim result in not reaching boost targets? I am underboosting below 3K rpms, and above 4500 rpms. At the same time, my fuel trims go negative during this time? Can I adjust my fuel tables in these rpm ranges so that I reach boost targets, or is this simply a symptom of small turbos at high altitude....take longer to spool and run out of air up top?

+1, great question.

[135Pats]

Originally Posted by dlbrooks18

+1, great question.

I've been fooling with the new 3D fueling tables, but haven't had a chance to really try anything (largely out of fear ).

I believe the answer is-yes.


Edit: Though i'm still not seeing how pulling out some fuel would cause you to not meet target boost or load. What's the supposed causal agent?

[Aerotest]

Fuel trims and boost are likely booth a result of altitude. Thin air means less fuel to target stoch and the thin air means less density and pressure ratio (read psi) out of the business end of the turbo. Try resetting the fuel trim amd AFR adaptations and drive the car around for a couple of days. Relog to see if fuel trims improved. Underboost may require more WGDC to help achieve target. What ever you do dont increase fueling to attempt boost increase.

[Jeff@TopGearSolutions]

The real question is how much fuel is the car trying to pull % wise?

Please post some logs.

You may just be underboost because you are at high altitude and need to tweak a few things to meet target.

[mike@x-ph.com]

You need to post logs so we know exactly what is going on

[Raptor04]

Here's the link to my log. Wedge has made some changes and I have also been making changes to the WGDC base table, Adder, and Ceiling tables. Fuel scalar is set to 1.20 for E50 blend.

http://www.datazap.me/u/raptor001/e50-2

I'm below target under 3K rpms and over 4500K rpms. I'm starting to think that this cannot be tuned out due to high altitude. However, I'm still running stock downpipes. So I think that might be an issue for the long spool time.

Fuel trim is being pulled by the DME when I initially go WOT. Other than that, the fuel trims look good to me. Besides the underboosting issues, I think the logs look as good as possible given the limited datalogging capability of the OFT.

[Jeff@TopGearSolutions]

Originally Posted by Raptor001

Here's the link to my log. Wedge has made some changes and I have also been making changes to the WGDC base table, Adder, and Ceiling tables. Fuel scalar is set to 1.20 for E50 blend.

http://www.datazap.me/u/raptor001/e50-2

I'm below target under 3K rpms and over 4500K rpms. I'm starting to think that this cannot be tuned out due to high altitude. However, I'm still running stock downpipes. So I think that might be an issue for the long spool time.

Fuel trim is being pulled by the DME when I initially go WOT. Other than that, the fuel trims look good to me. Besides the underboosting issues, I think the logs look as good as possible given the limited datalogging capability of the OFT.

Do you know the WGDC? I'd let wedge do his magic. He's arguably one of the best at working with flash tunes these days.