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Ask Triston Your Own Question
Category: Ford
Satisfied Customers: 1616
Experience:  5 Yrs. exp. ASE certified specalize electrical,brakes, a/c driveability
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I have a 2011 ford expedition that looses power under hard

Customer Question

I have a 2011 ford expedition that looses power under hard acceleration. We have changed the fuel pump and filter and the valve body in the transmission and had it programmed at the ford dealership. We also change the Mass Air flow sensor. There is NOT
any lights or codes. Spark plugs look good and is not showing any signs of misfire, but ford tech said the spark plugs can cause weird things. Tired of throwing money at it and not getting any results. NO codes, No lights. If you accelerate really slow it
will shift gears and go as it should, but if you give it a half or full pedal to get going or to pass someone it revs up, high rpms, but it doesn't gain any speed. I am already over 3000.00 into fixing this problem with no results. I cannot throw any more
money at guesses. Please help.
Submitted: 1 year ago.
Category: Ford
Expert:  Triston replied 1 year ago.

if you like to fix your own vehicles it may save you some money paying a Ford dealer $150 to diagnose the problem for you. other than that the there are only a few things that can cause these symptoms with setting codes and 1 is fuel

pressure but you replaced the pump already (but make sure you have at least 55 psi of fuel pressure while idling and reving the engine in park, if not reply back) fuel quality can cause it, so i would get a fuel sample in a bottle and take it to a ford dealer and have them let me know if its more that 10 percent alcohol (if its weak or contaminated you can tell that by looking at it or smelling if) next, you can remove the front 02 sensor (before the converters) and see if it runs better, if it does then you have clogged converters. lastly smell the transmission fluid, if it smell burned before the valve body replacement or after then you have will need a transmission overhaul (usually if something electrical fails in the transmission like the valve body or solenoids you'll get a check engine light, if you don't get a check engine light and there is a problem with the transmission the problem is usually clutches) replay back if you have any more question, please give a positive rating. thanks

Customer: replied 1 year ago.
HI,we drained the fuel when replaced pump, replaced fuel with fuel that we know is good. Muffler shop checked the cats and exhaust and said it was good. Transmission fluid was good, we serviced it due to milage and independent mechanic shop changed the transmission valve body, thought a solenioid wasnt working. Still has same problem. Went to Ford house to get the tcm, or something like that, programmed the Ford Tech suggested changing the spark plugs, when I told him it wasn't missing and had no lights, he said the plugs could do wierd things to the 5.4s. That's why I am asking here, I can't afford to throw more money at guesses and even our local Ford guys seem to want to guess. It doens't have any codes, but when you accelerate it falls on its face. At 50 if you accelerate to pass someone the rpms rev up but you are still doing 50. If you take off from a stop sign and give it the gas to jump out in traffic it revs up and doesnt really get going. but if you ease into it - it takes off like it is supposed to. There has to be some kind of problem and its not setting a code.
Expert:  Triston replied 1 year ago.

if the problem is the spark plugs the dealer should be able to verify and be 100 percent sure if they drive it with a scan tool and when the problem occur see what the spark is doing. i'm not sure why they are guessing. if you have 100k miles and have not replaced the spark plugs then they are over due.

Customer: replied 1 year ago.
The guy that did the trans programming told me in the parking lot that he would change them even though there is no misfire code. I dont think he actually checked out issue, just did what mechanic asked with trans programming. They are too busy to get me back in till the end of next week.
Expert:  Triston replied 1 year ago.

Yes that possible to have a weak spark that don't set a code but it will still show when looking at live misfire graphics, also there are software updates for the transmission so it did make sense to have that programmed and updated.

Customer: replied 1 year ago.
I guess I am going to take it to a different Ford Dealership and see if they can find the problem, I just cant afford to guess.
Expert:  Triston replied 1 year ago.

That what I'll do cause there there is no reason a ford dealer technician should guess if he can drive the truck and duplicate the problem you are having. Good luck I wish I could have been more helpful. Thank

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