Unusual indications & out of ideas

[wnorris]

2004 Grand Prix GTP

Hello and thanks in advance for anything you folks might have for me.. If this should be posted in another section of the forums or not at all on the forums just let me know and I'll move it.

The story is a couple weeks ago I found I was losing a significant amount of coolant and determined the issue was the lower intake manifold gasket. I purchased the gaskets I needed to complete the job and did that. My father, who has rebuilt a few dozen engines in his day helped me in the endeavor and everything seemed to go pretty well until it was time to start things back up again.

The engine had trouble idling and would rev then lull repeatedly, and the following additional symptoms would occur:

• Dash computer indicates "Engine Low power"
• Dash computer indicates stability system error (forget exact wording)
• TCS disengages itself
• Engine enters what I would call safe mode, enters a low idle and stops responding to throttle command
• The dash computer "Engine Boost" screen shows about 75% boost active even when the car is not running, and the screen does not change whatsoever when the engine is started until the cascade of failures above show up
• Following error codes register:

P0101 -

MAF circuit range/performance problem


P0069 -
MAP/MAF Throttle Position Correlation


P0068 -
Manifold Absolute Pressure


So far we have cleaned the MAF sensor, replaced the MAP sensor, looked exhaustively for vacuum leaks, cursed a lot, unplugged the battery to reset the computer, and verified blinker fluid level is above the fill line. I'm sure we've also toyed around with a few other pieces under there that I'm forgetting. We really are out of ideas here, and any and all help would be greatly appreciated.

Thank you!

[dcrews]

Did you pinch a wire under the intake? Been there, done that...

[J57ltr]

You have the connectors for the MAP and Barometric sensors swapped.

they are the 2 sensors that the rear of the supercharger the one on the drivers side is the MAP (has vacuum line attached) the on the passenger side is the barometric sensor (open to air). Having the connectors switched or the line on the wrong sensor will cause 2 of those errors. Do not idle the engine once it is in Reduced power mode. It locks timing at 15* ATDC and goes full rich and will smoke the catalytic convertor.



Jeff

[rottonj]

You have the connectors for the MAP and Barometric sensors swapped.

they are the 2 sensors that the rear of the supercharger the one on the drivers side is the MAP (has vacuum line attached) the on the passenger side is the barometric sensor (open to air). Having the connectors switched or the line on the wrong sensor will cause 2 of those errors. Do not idle the engine once it is in Reduced power mode. It locks timing at 15* ATDC and goes full rich and will smoke the catalytic convertor.



Jeff

Good call, I was thinking the same thing.