Situation

1. MAF Tune, E85, Walbro 416, FIC 1250s, -8 Feed,-6 Return
2. Steady state driving, between 3350-3450 RPM at highway speeds
3. Start to climb hill (I-44 has quality hills)
4. Maintain Throttle input at 33%.
5. Boost gauge is reading -2 / +0.5 psi
6. ECU has switched from closed loop to open loop - verified by O2 feedback trim going to 0.
7. AFR drops down to 16.5-17.2.
8. AFR will correct itself if I increase throttle input and go into positive boost territory.

Which table am I looking at within Tephra to fix this problem? Everything is 14.7 or richer in the Fuel Map, so I'm a bit confused. Log has been attached, affected areas are highlighted in yellow.

 

Ran another logging session this morning, more information derived -

1. 1byte Load ranges from 70-110
2. Fuel pump has switched to high voltage at load 50

Other than this, still lost on why it's running lean in these situations.

 

1. Injectors need scaling correctly - 15-10% too lean.
2. Once scaled fine tune using MAF Compensation table.

 

So if I understand correctly, if 4 cells of the entire large map don't match, change scaling? Everything else is spot on, but I'll give it the ol' college try.

 

Look up how to scale injectors and start there!

 

I'm intimately familiar with that thread; dropped the scaling 5% this morning and will see how it affects that particular load spot and WOT this evening.

I'm personally hesitant to adjust scaling for 4 load cells out of 750, but I'm apt to try new things when I'm not pushing the limits.

 

Dropped the scaling 5%, 860 to 812. Literally no change at all in the logs under the same conditions.

Attached is this log, highlighted yellow where the pucker factor exceeds "This shouldn't be that lean."

 

Try adding +15% fuel in the transition load cells where it goes lean. If that doesn't work it's time to take a detailed look at your fuel system, especially pressure at the injector rail. This should be 43.5 psi at idle and increase 1:1 with boost. Get an adapter and pressure gauge to diagnose it.
You may have a sticky regulator valve that is not adding fuel pressure smoothly as you go in to boost. You may have a leaky grommet on the fuel pump outlet that is dropping pressure. You may have a clogged filter that is restricting flow. Go through these one by one and you will figure it out.

 

I went on vacation and pondered this problem; mostly pondered the problem over seasonally inappropriate mojitos.

Solved - Added an inline fuel pressure damper, a Radium FPD-XR to be specific, to the fuel system directly before the fuel rail.

No lean spots, no zero, zilch, nada, negative. Reproducing the driving conditions from before and the fuel numbers matched the map exactly.

A similar lean condition was described in the 2150cc injector tuning thread and I decided to run with it.

 

Glad to hear you resolved it.

 

Very interesting I'm going to note that in my head that this was solved using this damper.