Reduced Engine power from new flashed ecu

[rfoster23g]

We have a 2009 Saturn Sky that will not pass emissions it will no matter what we do throw a perpetual PO420 catalyst efficiency code. We have replaced the catalytic converters, the O2 sensors, and even the manifold (after discovering a hairline crack. The code still shows up immediately after restarting no matter how many times we clear it. The car runs great no smoke no misfires and has less just a little over 100 thousand miles. We then came to the conclusion that the computer must be at fault so we purchased a used computer from a car at the salvage yard. So we decided to download the tune from the old ecu and attempt to flash it to the new computer. We spent 4 credits 2 to license the new ecu and then 2 to license the new OS flashed to the computer. The first thing we noticed is that the new computer still had the wrong vin and our scan tool believed the car to be a 2009 buick instead of a 2009 saturn sky. we tried several times unsuccessfully to do a vin change through the vin change wizard. we even tried reflashing several times using the write entire ecm option selected on the ecm and the bcm. Nothing worked the real kicker is that we then tried to see if at least the PO420 would not come back but as soon as we attempt to drive it the car goes straight into reduced engine power with the trans shifting at full line pressure and it will not rev over 3000 rpm. We tried doing a crank relearn several times with our scan tool to see if that was the problem with no luck. We don't think we are doing anything wrong but now we are out 4 credits and are left with a unhappy customer who's car will still not pass emmissions. Has somebody run into this problem before because we are completely out of ideas. Any help would be greatly appreciated.

[steelmesh]

We have a 2009 Saturn Sky that will not pass emissions it will no matter what we do throw a perpetual PO420 catalyst efficiency code. We have replaced the catalytic converters, the O2 sensors, and even the manifold (after discovering a hairline crack. The code still shows up immediately after restarting no matter how many times we clear it. The car runs great no smoke no misfires and has less just a little over 100 thousand miles. We then came to the conclusion that the computer must be at fault so we purchased a used computer from a car at the salvage yard. So we decided to download the tune from the old ecu and attempt to flash it to the new computer. We spent 4 credits 2 to license the new ecu and then 2 to license the new OS flashed to the computer. The first thing we noticed is that the new computer still had the wrong vin and our scan tool believed the car to be a 2009 buick instead of a 2009 saturn sky. we tried several times unsuccessfully to do a vin change through the vin change wizard. we even tried reflashing several times using the write entire ecm option selected on the ecm and the bcm. Nothing worked the real kicker is that we then tried to see if at least the PO420 would not come back but as soon as we attempt to drive it the car goes straight into reduced engine power with the trans shifting at full line pressure and it will not rev over 3000 rpm. We tried doing a crank relearn several times with our scan tool to see if that was the problem with no luck. We don't think we are doing anything wrong but now we are out 4 credits and are left with a unhappy customer who's car will still not pass emmissions. Has somebody run into this problem before because we are completely out of ideas. Any help would be greatly appreciated.

Something I learned later than sooner, is O2 sensor wiring is critical. It is critical because the O2 uses the physical copper wire jacket as a fresh air tube to reference. I am not saying this is your problem, but I can see it possibly causing issues like this.

Stuff that would cause an issue here:
1) Dielectric grease was introduced to the connector
2) Brake cleaner or solvents were introduced to the connector
3) O2 wire harness folded and zip tied
4) O2 wire harness pinched
5) Incorrect replacement O2 connector used, or improperly installed

[veee8]

You may be able to get the used ECM back to functional state with using a GM MDI to flash a new calibration for the Sky if the used ECM is of the same service number. There are certain segments that are not being written with the HP Tuners.