02 Ford Expo 4.6l Gremlins

[dee_dee_railed]

Looking for some advice.
Have an 02 Ford Explorer with 210k on the 4.6l V8. A few weeks back it started to miss while going uphill and the CEL came on later that day, even flashed at me. Disconnected and reconnected the battery, started fine and the CEL did not come back on, went for a test drive and it started to miss and run rough, pulled over, did not shut off, unplugged the MAF sensor and it immediately started running better. Got some MAFS cleaner, didn't help. Replaced the MAFS, still didn't help. While waiting on plugs and coils, things got worse, rough idle while in park and would stall at stop lights. Replaced the plugs and coils, now it won't idle at all, misses occasionally in the 1500rpm range, runs fantastic at 2000+, and no CES. Idle issue still goes away with the MAFS unplugged, and the CEL comes on at startup.
Could the replacement MAFS be bad?
IAC valve?
EGR issues?
Thanks!
Brett

[Dan Barlow]

Anything could be bad . I'd grab one from a junkyard . Preferably off a rear or side crashed one . Not from a junk yard like pull a part as most of those cars are there because the wouldn't run right .

[Russell]

Did you ever check the codes?

[dee_dee_railed]

Dan,
Good thinking, will check out the one local JY for odds and ends.
Russell,
Never did make it to Auto Zone to pull the codes before I started replacing parts. Now the CEL only comes on when I disconnect the MAFS.
Thanks Guys!

[Russell]

I would wonder if you got a bad maf or you have a leak somewhere. What about the wiring harness to the maf?

I would suggest getting a code scanner. The basic ones are pretty cheap. I also have a cheap blue tooth OBD2 plug that will pull codes with a free app on my phone. It was $11.59 on Amazon. I would never clear codes before reading them.


I would go back over my work make sure everything is hooked up correctly and drive it and wait for the CEL to come back on. When I put new plugs and boots on my 03 towncar. I left out one of the springs. I was feeling lazy so I just drove it around with the dead hole until the light came on it told me it was 6 or 7 don't remember. Saved time from having to pull them all. Does the explorer have the car intake? Could yours be cracked? Are you loosing coolent.

[dee_dee_railed]

Looks like all's it needed was plugs and coils. Just plugged in the original MAFS and it works perfect, the replacement I got must have been defective.
Thanks for the advice, will keep it all in mind for next time....and will get a code scanner on order, be ready for next time!
Brett