Ford 5.4L Stumble - Engine Troubleshooting


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Ford 5.4L Stumble

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Auto Repair Home>> Automotive Repair>> Engine Troubleshooting

wmhunter02
New User

Dec 26, 2009, 8:25 AM

Post #1 of 3 (2666 views)

Ford 5.4L Stumble	Sign In

2006 F150 5.4L 130K miles New plugs at 95K(!), Vacuum Booster recall fixed, fresh fuel/injector cleaner run thru

Without codes, your thoughts please!

Recent decrease in fuel economy (>10%)
Stumble when shifting into OD at low RPM's (<2000PRM)
Stumble in OD when challenged by grade
High Altitude driving (6000+ft)

Bill in Utah

Sidom
Veteran / Moderator
Sidom profile image

Dec 26, 2009, 12:35 PM

Post #2 of 3 (2644 views)

Re: Ford 5.4L Stumble	Sign In

Fuel economy can be so subjective....There are a lot of variables the can affect the mileage.... Just keeping an eye on some simples basics can help, tire air pressure and wheel alignment. Low tires will really kill your mpg and while an alignment can as well, if out far enough to affect economy, you will usually notice the tire wear that goes along with it.

Without seeing some scan data there is no real way to see if the system is in fuel control or struggling to stay in fuel control (which could affect mpg)

Running injector cleaner in the fuel tank is good for maintenance. When an injector/injectors starts to fail the 1st thing that goes is fuel economy (usually unnoticed), then it goes to a performance problem, then drivabililty and so on.

If caught early, cleaning can & does help. But it's a cleaner that is run thru the fuel rail with fuel system disabled. Cleaners in the tank or that are run thru a vacuum line usually aren't enough to clean a dirty injector but both have other useful purposes.

A dirty MAF can also affect mpg as well as performance. They make special cleaners available at any parts store for this. Once again caught early enough can save the sensor...(If you're running an AM oil base air filter, then your sensor is probably trash by now & cleaning won't fix it)

As far as the o/d problem, depending on how steep the grade is, it shouldn't be in o/d. If the problem you are having is only when in o/d then there could be something going on with the converter lockup but then again you are going to need a scan tool to help you diagnose it......

way2old
Veteran / Moderator
way2old profile image

Dec 27, 2009, 2:05 PM

Post #3 of 3 (2625 views)

Re: Ford 5.4L Stumble	Sign In

I would venture the MAF sensor as Sidom has mentioned. The thing that makes me think that is your high altitude problem.

Being way2old is why I need help from younger minds

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