Quote:
Originally Posted by Firstymer
I was informed by the staff at AutoZone I may have to replaced the Oxygen sensor, MAF sensor, spark plugs & wires. I already tried cleaning and disconnecting the MAF sensor and no improvement. Can someone guide me in the right direction or where should I start?
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Never EVER follow their advice; stick to having the codes read and drive away ASAP, otherwise you will likely end up throwing a bunch of parts at it without actually fixing the problem.
Quote:
Originally Posted by grandprixgtx00
P0449 (Mass Air Flow) can cause a random multiple missfire (P0300). A bad ignition coil would typically cause a specific cylinder missfire, along with the cylinder that shares that coil pack.
The P0102 is just an evap code, most likely caused by a loose gascap.
I would suggest clearing the codes by disconnecting the battery for 10 minures, take the car for a ride to trip the check engine light again, then see what codes are in there again.
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It's the other way around, P0102 is for the MAF and P0449 is for the EVAP, he's right though.
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1.- If you tried disconnecting the MAF sensor AND you didn't drive the car after, then that's likely the reason from the P0102 code. It should go away after 2-3 ignition cycles.
2.- The EVAP solenoid could be either bad, OR there might be a broken line between the canister and intake manifold. With the permanent flow of air form the atmosphere, it would trick the PCM into thinking the vent valve is connected but stuck open and not allowing vacuum at the fuel tank. Check those lines from the EVAP canister (rear driver side on quarter panel) to the intake manifold.
3.- A vacuum leak can cause random misfires if big enough, HOWEVER, it's not the only cause for it. Low fuel pressure can also cause random misfires and would definitely cause rough idle and sluggish acceleration; an ignition problem (bad ICM) could do the same but you would likely smell the unburned fuel in the exhaust.
If you could get ahold of a fuel pressure tester and a scanner that reads live data, it would surely be easier to diagnose. I have a friend in Washington who rented both items from autozone (got his money back after returning them); maybe your local autozone has the same items.
If you can rent the scanner with live data, before you erase any codes, WRITE DOWN any information contained within the FREEZE FRAME option.
I hope this helps,
Oscar.