Help 99 grand am map high keeps dropping to -6 at idle and cutting out @ idle simult.

[carmasterkenny]

Please help my 99 grand am 2.4l is missing at idle only. timing is going to -6 on scanner at same time as miss and high map at idle random misfire code and map voltage high code replaced crank sensor and cam sensor no effect. only at idle.

brakes also a little stiff maybe and indication of vac. please help

94,000 miles

[3100]

give me some of live engine data numbers at idle, and at 2000 rpm. Any codes?

sounds like vacuum leak somewhere if your brakes are stiff (power booster not getting enough vacuum)

[carmasterkenny]

hi thanx the only codes are random mulitple missfire and map voltage high i unplug the battery and start it it runs fine for a second untill the computer takes over and anything over idle the timing sets to 15 past tdc and runs perfect idle is low when missing thanx again

[3100]

check all the vacuum lines, try to find vacuum leak. Does your scanner show intake manifold vacuum when engine is running? or do you have vacuum gauge that you can connect to any vacuum port on the intake to measure vacuum?

Random cylinder misfires most of the time is a sign of vacuum leak. Also test map sensor.