SOLVED: Need help with bogging and misfires, persistent P0171 & P0174 lean DTCs

[victell]

SOLVED: MAF was at fault.

New intake boot and MAF arrived from FCP. Installed the intake boot, performed smoke test, found no additional leaks. Started engine, still ran terrible.

Installed new VDO MAF mass airflow sensor, started engine, immediately ran better. I have driven about 100 miles on since the MAF replacement and no MILs or drivability issues to date.

Conclusion: even if there are no codes for MAF and the live data seems to be responding correctly, the MAF may still be at fault. Disconnect the MAF before starting the engine, then drive the vehicle. If there is a change then the MAF is likely at fault. Thanks 80stech for the tip.

Originally Posted by 80stech

Have you driven with the maf disconnected (before starting engine) ?

[aureliusmax]

Originally Posted by victell

SOLVED: MAF was at fault.

New intake boot and MAF arrived from FCP. Installed the intake boot, performed smoke test, found no additional leaks. Started engine, still ran terrible.

Installed new VDO MAF mass airflow sensor, started engine, immediately ran better. I have driven about 100 miles on since the MAF replacement and no MILs or drivability issues to date.

Conclusion: even if there are no codes for MAF and the live data seems to be responding correctly, the MAF may still be at fault. Disconnect the MAF before starting the engine, then drive the vehicle. If there is a change then the MAF is likely at fault. Thanks 80stech for the tip.

good for you updating your fault. too many forums out there, always a hit and run and never come back to update.

[Effduration]

Originally Posted by victell

SOLVED: MAF was at fault.

Disconnect the MAF before starting the engine, then drive the vehicle. If there is a change then the MAF is likely at fault.

This CAN indicate a bad MAF...but a vacuum leak is more likely if the car runs better when unplugging the MAF..


Happy to see you fixed it and thanks for coming back to post a follow-up...