Throttle Unexpectedly Snaps Shut

[IronBird]

The engine is a 2013 LC9 from a 2013 Silverado. Twin Turbos, stock cam, 6 spd manual. The E38 ECM is from the Silverado and I'm not running a TCM.

I've been chasing an issue with the throttle will unexpectedly close while under power (usually under boost). I've been doing some MAF tuning and I caught it twice in the logs. There's another weird thing that happens after the throttle closes...most of the PIDs in the log drop out. The first time it happened, my tach stopped reading as well. It doesn't happen often but I can't seem to find the pattern.

I've attached the two log files and the tune from the second run (the only difference between the runs is the MAF table). Does anybody have any ideas?

Look at the following time stamps:

MAF Tune_A 00:05:18:014
MAF Tune_D 00:05:22:360

Thanks in advance.

-Tom
2023-03-19 MAF Tune_D.hptMAF Tune_A.hplMAF Tune_D.hpl

[GHuggins]

What map sensor are you running? It looks and sounds like you have a 5v shorting out. You have codes for ect, map and O2... Wiring melted somewhere? Wrong map installed?

[IronBird]

I’m using a 2 bar MAP, GM 12615136. I thought it could be a wiring thing, which is why I started logging Throttle Voltage, but I didn’t see anything unusual in the log. I checked all the wiring that was visible, and there’s nothing near the exhaust. I may have to pull some harnesses apart and dig further. Thanks!

[GHuggins]

offset should be 8 then. Shouldn't be enough to cause the problem though. You may even have a sensor shorting causing the problem if wiring is good.

[Alvin]

The engine is a 2013 LC9 from a 2013 Silverado. Twin Turbos, stock cam, 6 spd manual. The E38 ECM is from the Silverado and I'm not running a TCM.

I've been chasing an issue with the throttle will unexpectedly close while under power (usually under boost). I've been doing some MAF tuning and I caught it twice in the logs. There's another weird thing that happens after the throttle closes...most of the PIDs in the log drop out. The first time it happened, my tach stopped reading as well. It doesn't happen often but I can't seem to find the pattern.

I've attached the two log files and the tune from the second run (the only difference between the runs is the MAF table). Does anybody have any ideas?

Look at the following time stamps:

MAF Tune_A 00:05:18:014
MAF Tune_D 00:05:22:360

Thanks in advance.

-Tom
2023-03-19 MAF Tune_D.hptMAF Tune_A.hplMAF Tune_D.hpl

This almost looks like a loose ground situation to me. If you look all the data gets lost for a second on shutdown. HPTuners will draw a straight line between the last two good data points in the line display. When throttle closed MAP would have slammed down also. Also.. pretty much all data is junk after the shut down. This is like a hard restart or something.. like a loose ground


Check for bad grounds.

Check for codes after it shuts down like this.