Random loss of power

[Niemer]

Had anyone seen this before? Steady throttle in PE and power just drops out, no loss of traction and in manual mode. GMVE, Cylinder airmass, and injector pulsewidth amongst other things just drop to 0, the attached log shows this at frame 6780. This happened twice this morning, but TC was going nuts the first time so that log is pretty messy.

[Niemer]

Happened again this morning. There are a couple of times I entered PE in this log and the last with no issue, shows up at frame 8660

[Niemer]

Anyone?

[SultanHassanMasTuning]

that is strange... try logging less PID....how does the car feel?

[Niemer]

Thanks for the reply. It feels like hitting a wall or the throttle snapping shut all of a sudden. I've switched back to MAF only and made a few changes to the trans setting and it hasn't happened again. I'll keep watching for it to happen.

[bottlefed11]

Had issue with 2011 Silverado PE would not work in manual mode but fine in drive Dave Steck solved my problem

[Niemer]

This same thing seems to have happened once again yesterday afternoon after being fine for quite some time. I cant seem to figure out what causes it, airflow just drops to 0, and it's not just in the scanner, it actually happens.

[realcanuk]

Almost looks like the TB is slamming shut, but haven't really seen that on a stock TB.... more common on aftermarkets.

[Niemer]

It sure feels like it.

[GHuggins]

Airflow won't drop to 0 g/sec even with plate completely shut. Looks like your hitting a maf limit or wiring to maf or just bad maf... Just to verify, as long as your sd is close, put it into straight sd and duplicate conditions to see whether or not the problem is still present or not. Make sure you change to sd in tune.

Plus unless you've killed tb dtcs, if tb were closing or loosing connections it should immediately set a dtc and rep...

[Niemer]

This is in SD only, and open loop within a couple percent, MAF isn't even plugged in. The only DTCs that are disabled are those related to the MAF and the ones disabled for the blower, P0068 I believe.

[GHuggins]

OK, you had MAF g/sec in the pic you posted and it was at 0... So watched the data log. Only saw it occur in one place. At that particular point the electronic throttle control stayed at commanded 69%. Before the complete fuel cut took place I saw both boost and delivered torque dropping. So I went to the tune and took a very brief look at the torque limits. Under Engine - Torque Management - Default Trans Limit - This is still stock 300 something. Start here and go from there. Looked like where it happened in the data log the ecm cut the fuel. Might want to add some of the other desired and actual pids to your logger to help track down the problem.

[Niemer]

I don't know how much I want to mess with the default trans limit since it looks like it's only used when communication to the TCM is lost. I'd rather have that as a fail safe. I have all the fuel cuts, at least that I could find, disabled, so it shouldn't be cutting fuel ever. It also happens unpredictably so it's going to be a hard one to pinpoint. I'll log all of the fuel cut PIDs I can find just in case.