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I have a 06 GTO and when I 1st started tuning with the speed density VE tables my idle MAP pressure was at 21 kpa and could hit 105 kpa at WOT. After tuning for a while with all the modifiers like COT, DFCO and others turned off it seems now my idle sits at 38 kpa and it's not easy or cannot hit 105 kpa during WOT pulls.
Started to think perhaps my cats got damaged or possibly have a vacuum leak but what's your thoughts on how my engine has changed or what can I do to troubleshoot?
I know spraying carb cleaner around intake and vacuum hoses should help to detect leaks but is there something else that I can do as well?
Easy way to find out if its the tune is revert to the original tune and see if the problem persists.
IF it is the tune, more details on what you changed would give a better chance of getting you answers.
No even with original, precious or reverted tunes the problem stays same. MAP at idle 38kpa and WOT does not reach 105
WOT manifold pressure is related to the barometric pressure where you are located. It's pretty rare to see baro pressures above 101 kPa even at sea level.
105 is in interesting value because that's the limit of some baro sensors. Perhaps you had a voltage offset in your 5V supply, or sensor ground. That caused the high or low readings.
I can understand that and that's fine but my main concern is at idle when it was at 21 kpa and after a few months now sits at 38 kpa. Possibly the MAP sensor should be checked out then with volt ohm meter?
Combination of ignition timing and idle throttle openning can effect idle vacuum.
True but if I put the original tune back in and it still has the same results of MAP readings then what would be your next steps?
Also this car only has 24k miles and have suspicion that the cats have been damaged causing back pressure in exhaust to be excessive from tuning so long with COT, DFCO etc being turned off.
Not possible or? Is 38 kpa a normal idle MAP pressure?