Loss of Pedal Control when making boost

[[email protected]]

This is a 6.0 swap (with electronic throttle) in an 80's Malibu with a TH400 and 2007 Silverado Cal. Customer called indicating after tuning at a shop local to him he had loss of throttle when making boost.
Replicated this on our dyno. When the car makes approximately 8psi the throttle goes dead and the ignition needs to be cycled for the electronic throttle to work again.

Does this require a manual trans cal? I did try disabling all the trans codes that came up but the issue persists.
I also tried various other parameter settings I found searching the HPT forum but nothing seemed to correct the issue.

Any help would be greatly appreciated.

Here's the current state of the tune.

[MikeOD]

Do you have a log of it happening? Can you log with dynamic airflow?

If you look in Engine Diagnostics, there is an airflow section, and there are a few tables about calculated airflow. In the 2.25 beta, the first table there, "Calc Airmass - P1514/P0068 Error"...if you exceed this much dynamic air for any given TPS, you'll trigger reduced engine power (even with the code disabled) and the throttle will basically go dead...it's a safety.

At 8 PSI, you might be able to calibrate around it, but if not, you'll need to scale the tune. Higher power level Gen 3 ETC stuff usually I need to scale by 50% to avoid this.

To try to tune it...max the table out, flash that in, then open up the VCM scanner and create a new histogram...TPS % at the top (match the axis to the table I mentioned above) and RPM down the side, again, match the axis...and log dynamic airflow in that histogram.

Set the scanner to show you the highest values, not the averages but the highest...paste those values directly into the table in HPTuners, fill in the gaps to match as best you can, then multiply the entire table by something like 1.15 or 1.2...this will allow for the vehicle to keep the table as a safety net.

If you still trip reduced engine power when the table is maxed out and you're trying to log it to create it, then you'll need to scale the tune. The max value you can enter in the table is 4.10 g/sec, but there seems to be a lower limit coded somewhere in the PCM so you may find you still hit that wall...if you do, you can scale the tune 50%, and the dynamic airflow will cut in half, and then you can do as I described above to tune this table. I wouldn't leave it maxed out.

[[email protected]]

Do you have a log of it happening? Can you log with dynamic airflow?

If you look in Engine Diagnostics, there is an airflow section, and there are a few tables about calculated airflow. In the 2.25 beta, the first table there, "Calc Airmass - P1514/P0068 Error"...if you exceed this much dynamic air for any given TPS, you'll trigger reduced engine power (even with the code disabled) and the throttle will basically go dead...it's a safety.

At 8 PSI, you might be able to calibrate around it, but if not, you'll need to scale the tune. Higher power level Gen 3 ETC stuff usually I need to scale by 50% to avoid this.

To try to tune it...max the table out, flash that in, then open up the VCM scanner and create a new histogram...TPS % at the top (match the axis to the table I mentioned above) and RPM down the side, again, match the axis...and log dynamic airflow in that histogram.

Set the scanner to show you the highest values, not the averages but the highest...paste those values directly into the table in HPTuners, fill in the gaps to match as best you can, then multiply the entire table by something like 1.15 or 1.2...this will allow for the vehicle to keep the table as a safety net.

If you still trip reduced engine power when the table is maxed out and you're trying to log it to create it, then you'll need to scale the tune. The max value you can enter in the table is 4.10 g/sec, but there seems to be a lower limit coded somewhere in the PCM so you may find you still hit that wall...if you do, you can scale the tune 50%, and the dynamic airflow will cut in half, and then you can do as I described above to tune this table. I wouldn't leave it maxed out.

Thanks for the response! The customer brought in his own laptop and MPVI so I do not have a copy of the logs we took. I did grab the last tune file which is what I attached. After reading your suggestions I did use the beta to open the tune file on my laptop and sure enough the table you mentioned was now visible. I will ask the customer to download the beta and I'll remote into his laptop and try your suggestions.

Thanks again!
Mike