I have a customer that has had his truck "tuned" by a local guy.. I went and read the reviews for the shop he had the "tune" done at.. Let's just say, the reviews are pretty bad. But, I won't base my entire opinion on just the reviews as I know sometimes customers get angry and they just want to burn your business down.. So, that's a possibility. I pulled a copy of his "tune"-it's a 2009 Chevy Silverado that we swapped from a 4L60E over to a 4L80E, and what I'm seeing leaves me with questions..
The truck has LT headers and the O2 sensors are present and connected. In the tune the other shop has ALL DTC's for ALL O2 sensors effectively turned off-nothing reporting, no SES. It is a MAF only tune. VVE tables appear all stock, and dynamic airflow disable set to 200... but he still has the temperatures for closed loop operation set such that it should be trying to go into closed loop-even though he has all the DTC's turned off for all O2's. Will the PCM still utilize the O2 sensors and adjust fueling if the MAF table is off? In the Gen 3's I know that the MAF still references the VE table so it's always best to tune the VE table, and MAF, on the Gen 3's... I would think it's the same on Gen 4's, but could be wrong.
Why disable ALL O2 sensor information?
Why disable P0300 Random misfire detected?
Why disable the brake switch DTC's when the vehicle HAS an automatic transmission that relies on that signal?
Why disable all other EVAP Emissions codes, and then leave P0496 active?
Why disable TRANS OVER TEMP condition DTC's?
As a test with the engine idling I unplugged the MAF and the engine began laboring like it was only running on 2 or 3 cylinders and then died after just a few seconds. This leads me to believe that if the customer ever suffers a MAF failure, he is going to be on the side of the road.
I'll post up a copy of the tune for review... Any/ALL comments are welcome. At this point I would like to make the customer aware of what I'm seeing and refer the customer out to another shop for a better tune. I don't do tuning for customers, just mechanical repairs.