Got Her Running After 6 Years! But…Wants to Die
V6 2.8 MPFI Stock Firebird

Engine turns over normally and starts up but then quickly dies. Start it up again, and have to pump gas to keep it running. When I press the gas pedal it will rev up high then like chokes out and wants to die, give it gas and it revs up again then wants to die. I can finally get it to run on it’s own eventually, but the idle is erratic. Up and Down, Up and Down…I know it could be 100 different things, but maybe someone has had to same symptoms and Can point me in the right direction. Thanks!


Checked All Vac Hoses
New Fuel Pump
Checked Cap And Wires,
Changed Oil Clean
New Fuel Filter
Clean Air Filter
Tested and Cleaned IAC
Checked MAF Looked OK?
Checked PVC it Rattles

 

Are any error codes present? It's easy to retrieve them and report your findings.

When the IAC was cleaned, was the pintle removed, spring re-tensioned, rack cleaned and lubricated? Cleaning the passages and cone are a good step, but not enough to restore a sluggish stepper motor.

Does it have fresh fuel? Since the pump was changes, I'd expect it to have fresh fuel, but if not, pour in about 5 gallons of the LOWEST octane fuel you can get (NOT high octane!) the allow the pump to cycle long enough to mix the tank contents. This may require jumpering the fuel pump power and allowing it to run for ten minutes or longer.

In case the hunting/surging is due to an internal vacuum leak, temporarily disconnect the vacuum line to the EGR valve. If the EGR is inadvertently opening this will resolve that.

In case the brake power booster is leaking internally, remove and plug the vacuum line to it. DO NOT drive the vehicle without reconnecting the line.

If it hasn't already been done, test the standing (KOEO) fuel pressure. It requires a minimum 35 PSIG to operate properly. 37 is better. 43 is ideal.

 

holy crap batman! Checked out to be a bad MAF. I unplugged it and the She runs like new!

starts right up, Idles, wants to go fast....

 

Before condemning the MAF, carefully clean the screens and sensor element with an electronics safe cleaning spray. Verify that the MAF power relay and the INJ1 fuse are intact. Also verify that the intake tract ducts are intact and not leaking, especially between the MAF and throttle body. It is still a good idea to verify that there are no other vacuum leaks, external or internal.

If you have a bi-directional scanner the MAF counts can be checked by scanning the ECM. If you have a meter with a duty cycle or frequency counter function the MAF frequency output can be checked right at the sensor. The V-6 MAF is the FM type, so a DC voltmeter will be of little use here. At normal hot idle the MAF should produce about a 30Hz signal.

Just for complete clarity, what model year is the car?