Shuttering when trying to accelerate

JOE N

MEMBER
2000 FORD EXPEDITION
5.4L
V8
4WD
AUTOMATIC
375,000 MILES

The wife has experienced the truck shaking and shuttering when trying to accelerate. When it happens, you can’t drive the truck very fast and the more gas you try to give the engine the slower it goes. The engine is not throwing any codes. It does not run like this all the time but when it does, it can leave you stranded looking for a tow truck. The engine and trans are new with about 30k miles on them.

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Hi,

When this happens, do you need to wait until the vehicle cools off before it will restart? I ask because what you described sounds similar to an issue with the crankshaft position sensor. Take a look through this link and let me know if it mirrors what you experience:
https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

Next, the idea that it slows down the more you press the throttle leads me to think there is an issue with fuel pressure. Has the fuel filter been changed recently or has the fuel pressure been checked? If not, that is another thing you should check. Here is a link showing in general how it's done:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Let me know as much as you can and what has been done so far.

Take care,

Joe

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Saturday, February 19th, 2022 AT 6:02 PM

JOE N

MEMBER
2 POSTS

My wife bought this truck new in 2000 and has put over 375,000 on it in the 22 years she has owned it. This problem has been on going for about 6 months. The truck had this problem about 6 months ago and we had it tower to our mechanic’s shop. He tried for a week to get it to do something but to no avail. We picked it up and my wife drove the truck for about 4 months before it did it again. She was in Tucson when it happened again. I told her to park the truck and shut it down for a couple minutes. When she started it up again all was good for about another month. Our mechanic has had the truck this time for a little over 3 weeks trying to get to the bottom of this mystery. It did mess up on him a week and a half ago on his way home. He nursed it home and jumped out and tested fuel pressure and shot the cats real quick. Cat temperatures were normal and fuel pressure was normal. It was still running badly but there were no codes. He let it set over night and drove it back to his shop the next day with no problem and it has not messed up sense. My mechanic is a very up-standing guy. He is not the kind to just throw a bunch of parts at a problem hoping to get lucky. He is stumped right now because there are no codes to help him hone in on the problem. The engine was replaced about 5 years ago with about 30k miles on it now. The Transmission was replaced about 3 months ago when the torque converter went out. If you need more info, I will try to get it tomorrow when I talk to my mech. Thanks again for looking into this.

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Saturday, February 19th, 2022 AT 8:46 PM

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Hi,

The idea that there are no codes is leading me in the direction of the crankshaft position sensor. When they start going bad, they are adversely affected by heat. Interestingly, a faulty crank sensor may or may not set a code.

If the fuel pressure was within spec and no indication of an issue at the converters, it's likely not related to the fuel system.

Has he tried driving with a scan tool connected to see if there are misfires happening when this happens? Also, could you find out what both the short and long-term fuel trims are?

Let me know.

Joe

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Saturday, February 19th, 2022 AT 9:28 PM