00 4.6 Expedition Chugging

[bdnwtkfg]

ok
I've been around and around with this:
The motor chugs at low rpm - Kicked a code (I forget I think p0171) Lean condition left and right bank)

I cleaned the MAF
I then REPLACED the MAF
cleared code
Came right back
Turned out the PCV hose was dried out and cracked - THAT got replaced.
Cleared code.
Engine still chugging at 40mph ish

Checked fuel pressure
KOEOff 28 psi
KOEOn 25 psi

pulled line of fuel regulator - PSI jumped to 35 0 seem to rum fine w/o it.

Started chugging again

Replaced Fuel pressure regulator & new OEM fuel filter.

Seemed to run fine

Pressure: 31-32 engine off
28-30 engine on.

seemed to run just fine.
Now chugging again!

I READ WHERE A COIL PACK may be the cause. That the computer (not kicking a code) will see the coil pack mis firing, and reduce the fuel pressure??? WTH?

The ONLY thing I HAVENT REPLACED, is the fuel pump. I am avoiding that like the plague.

I also read a fuel line on top of the tank could be cracked... but you would smell / see fuel in a pressurized system

ANYONE HAVE THE SAME PROBLEM?

Solutions??

Thanks all!!

Big Dave

 

[98EXPnSRQ]

I replaced my fuel pump a few months ago. It wasn't hard to do. Remove the spare tire and you have loads of room to work. Not saying that's your problem.