In need of help...

[svillachica]

My 2006 Expedition Limited (148,000 miles) started having some hesitation issues, no codes though...
I replaced the following so far:
-Spark plugs and COP'S.
-FPDM
-Fuel and air filter
-Both VCT Solenoids
-I also cleaned the MAF Sensor
While its running better, now the engine rattles and hesitates while driving under 1000 rpm, especially going up hill.
At this point I'm just about out of ideas, and trust me, any help is greatly appreciated.

 

[DUNE RCR]

Might seem far fetched but have your alternator tested at a reputable shop(not advanced or auto zone, they only make sure it's charging). My 99 explorer had nearly the same problem you are having. I replaced nearly every sensor under the hood and did a full tune up with no change. Had my alternator tested at a place that rebuilds starters and alternators and the diodes were bad sending a/c currents through the vehicles electrical(which is a d/c system). Might not be your problem but it's worth a shot and if it is bad you can have it rebuilt their too.

 

[svillachica]

Interesting...I wonder if I can test that myself using a meter...I'll give it a try...Thanks!

 

[stamp11127]

Charging voltage usually runs 13.5-14.5 volts at 1500 rpm.

See the link for an a/c ripple test with a dmm:

Test - Ripple

 

[svillachica]

So I drove the car with a manual fuel pressure gauge connected to the fuel rail, and it never went passed 40psi, the range was from 28psi to 40psi, is that normal or is that too weak? As far as I know, the range should be 35psi to 70psi.

 

[stamp11127]

2006 fuel pressure when running is 28-45 psi per the service manual.

 

[svillachica]

I guess is not the fuel pump...ugh...