E38 Loss of PE 4000 rpm

[TJ63]

Please help troubleshoot. My truck goes lean when in PE mode. It seems to always happen at 4000 rpm, it's like a step transition. You can see where I'm asking for ~.85 lambda and fueling accordingly then all of a sudden fueling changes to ~1.06 lambda. I see about a 10 psi drop in fuel pressure about the same time. I've been reading the forum and thought disabling desoot mode was going to be the answer but it did not help. This also happened when using my MAF tuning calibration. The truck is a 2011 silverado 4.8 swapped to a 6.0, high compression pistons, cam 283/286 lift .585/.585 LSA 112, VVT delete, stock headers with cats, truck manifold with 50# injectors (12613412), 6L90. Check out my log at 7:15:16. Thanks!

[Alvin]

That is a tuning issue. It's not loosing PE. The ECM is still commanded a good EQ ratio.. But your wideband is going up. Add airflow to the MAF table or VE depending on how you tuned it.

[Alvin]

You have a pretty serous dip in fuel pressure, and low fuel pressure seemingly commanded anyway at the same spot.

[TJ63]

Since it occurred during MAF tuning and in my normal calibration which uses both VVE and MAF I thought the same thing and added airflow to my MAF curve in that 8000 Hz range but it didn't seem to help. I think my fueling just can't keep up with the commanded for some reason. The fuel pressure drop does concern me and maybe I should ask for more pressure before I get to that problem area.

[verlon]

Disable Injector Gain

[TJ63]

Thanks, I will give that a try. I went through my history and I think it was changed by accident. My original ECM read had it disabled and I see the warning in HPTuners that says "caution may cause high RPM operation problems". I will give it a go and report back.

[Cringer]

Disable Injector Gain

I came to say the same thing

[Cringer]

Thanks, I will give that a try. I went through my history and I think it was changed by accident. My original ECM read had it disabled and I see the warning in HPTuners that says "caution may cause high RPM operation problems". I will give it a go and report back.

A while back I had inadvertently set my injector gain setting to enabled as well. I think I knicked the mouse wheel at the right time and it flipped to enabled. I was new to tuning at the time and was chasing my tail on what the issue was. I ended up destroying a set of spark plugs while figuring it out.

[TJ63]

Thanks for the support! Disabling the the injector gain did the trick. Yeah this was a very dangerous mistake and looking back was a very likely cause of when I seized my #1 rod bearing and had to rebuild.