Hi guys,

I have an '86 Trans Am with the TPI 305...last year the car suddenly would barely start...I limped it to my brother's house and we checked it out and his diognostic tool said it was a MAF prob...the car will barely run ( if it starts! ) with the MAF plugged in but unplug the sensor and the car starts and runs great!!!!...we went up to our local NAPA store and the guy's let me hook up new a MAF sensor...and the same thing happened...won't start with the sensor plugged in...runs fine with it unplugged!...we even tried the MAF sensor from my brother's IROC Camaro...no luck...we are at a complete standstill with my car...I'm hopeing someone out there can shed some light on this!...TIA!!!!!

Dave

 

Your MAF is (was?) working correctly. It is reporting to the ECM the mass of air flowing through it based upon volume and the voltage of the source. It reports through the electrical connector and receives power through the MAF Power and MAF Burnoff relays on the firewall.

With the ignition power on you need to verify the presence of a minimum +12.6VDC at the "E" terminal on the MAF connector. If the voltage is low check the MAF Power relay and connections.

Verify a good ground on both the "A" and "B" terminals in that connector. The "B" terminal is an engine ground and the "A" terminal is the ECM ground. Both need to provide a good ground.

Make sure the "D" terminal has no voltage or the MAF will be reporting an erroneously high signal due to the active burnoff cycle. If there is power on the "D" terminal remove the MAF Burnoff relay and test the voltages again. If the MAF Burnoff relay is providing power you can exchange it with the MAF Power relay and test again.



If the voltages are correct with the ignition on, check the intake duct system closely for leaks, cracks, holes, and anything which would admit air to the engine without it flowing through the MAF. Pay close attention to the intake flexible bellows and blow molded rectangular intake duct.

Intake leaks include the PCV system so you must not use a breather cap on the oil filler. All the hoses must be properly connected. The power brake booster must also be intact, as well as injector O rings, gaskets for the intake, throttle body, runners, and EGR. The EGR valve must also be sealed and not leaking through.

 

Thank's Vader!!!...well that's a start!