Hi everyone, I'm not a noob, and been using HP tuners for a few years to dial in my 5.3L '02 Tahoe and my dads '03 corvette. Mostly tweaking the timing maps on both vehicles and the transmission settings on the Tahoe, but not too much with the fuel curves because some spark cleanup is really all they needed. However.....
I am no longer getting a reading from my MAP sensor through HP tuners on the 5.3L. I can see and feel that the timing is stuck on the 15 kPa band, the lowest, and so none of the timing maps or fuel maps are reading correctly. All the maps seem to be just following the 15 kPa line and the Tahoe still runs, but not that good. It is high mileage so I just changed out the MAP sensor and thought I'd be done with it. No change... actually worse, a little.
Since I assume my new MAP sensor is good, I don't have a vacuum pump to test, my conclusion is somehow the PCM is not reading the sensor correctly and the reading is not showing up on the HP Tuners interface. How do I go about troubleshooting this further?
Many thanks in advance.
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Originally Posted by 5FDP
