I wired up my DSP5 last night and got the tune switching working, but since I've done that, every time I start the truck, my CEL comes on and the DTC's show a turbo/supercharger overboost code. WTF??? My boost gauge has yet to go over 25 psi. Data logged and didn't go over 26 psi. I clear the codes and next start they come back again. Any ideas?? I've searched and came up w/ the MAF possibly tripping these codes, but I have the stock airbox/filter on again and the MAF is clean.

Try logging actual boost using the scan tool. After you scan, open the tune with the log file also open. Go through the scan file and watch which cells are highlighted in the desired boost table in the tune (this will automatically happen with both programs running). Compare these values to the values in table C0805 to see when the overboost condition is triggered.

Alternatively, increase all of the values in C0805 until the light doesn't come on. This shouldn't effect drivability as long as there are no underlying causes for the overboost code. Does the truck drive well? Does it code with the stock tune?

Nick

Wow! Never even thought of looking there, duh.... I just set the min. test RPM's for 4500 and the max test to 4600, thereby disabling running a over/underboost test. I have a boost gauge and data log my new tunes to be sure I'm not overboosting as it is, so I don't need the MIL to trip over it. THANKS! :)