4.6L ford F-150 running rough??


Old 03-06-04, 03:26 PM
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Join Date: Dec 2001
Location: middleboro,ma
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Question 4.6L ford F-150 running rough??

I recently bought a 97'F-150 4x4 with the 4.6L motor.It has 73,000 miles,and seems in good cond.
I've been feeling this roughness or stumbling feeling around 40mph,and 1500rpm...
Otherwise it has plenty of power,and runs great?It doesn't do it all the time,but its alway around that speed and rpm.
The dealer replaced wires,plugs,fuel filter,everything they could think of I guess,and it still does it sometimes???Any ideas??
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Old 03-06-04, 04:31 PM
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it maybe the air flow sensor or idle air control valve.this r my guesses
Old 03-06-04, 04:47 PM
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Join Date: Oct 2003
Location: Boynton Beach Florida
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Originally posted by fordman30
it maybe the air flow sensor or idle air control valve.this r my guesses
I'd say neither one of those things would give those symptoms.
There are many other things that could fall into that category. Can you tell if your actually getting a cylinder miss? You could have a vacuum leak, and EGR problem or even a dirty fuel injector. It's almost impossible to diagnose something like that without being there. This may be a time to have a professional take a look. You could throw a lot of parts at it without even being close to the problem.
Old 03-06-04, 04:53 PM
Join Date: Jun 2002
Location: Long Island, NY
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Hi cschroth1,

Its best not to start mutiple threads on the same problem. Its best for continuity to keep them together.

In one of the other posts I asked you if it happen while in OD lock-up... you never replied.

In another post you stated you had a shudder.....is this the same problem?

I told you what the shudder was, did you change the trans fluid and it didn't correct the problem?

Last edited by toyotaman11769; 03-07-04 at 02:35 AM.
Old 03-07-04, 03:35 AM
Thread Starter
Join Date: Dec 2001
Location: middleboro,ma
Posts: 279
Question 4.6L motor problem?

Sorry about the confusion on the postings..
Iam confused about what you are calling O.D. lock-up?
As far as the shutter (washboard) feeling I've gotten that 2 times in the 50 days I've owned it.
I talked again with the used car dealer,they want me to take the mechanic at thier transmission shop for a ride,so he can feel what its doing?
So I haven't gotten the tranny fluid changed yet.
Do tou think that changing the fluid could fix both problems?
Its strange,because it doesn't seem to do it all the time?
It almost feels like it mis-firing or hesitating?Its always around 40mph. (1500 rpm).
Like I said before otherwise it runs great!The dealer said he talked to the man that traded it in,and he too felt the problem,and brought it to dealers,etc and was told thats normal??
I don't buy that!
It should never hesitate or nything on a regular basis!
Anyways Iam waiting to get in to see thier transmission shop.
This truck also had a O.D light flashing after I bought it.It was traced to a speed sensor.Thats fixed now.
Is thier any way for me to tell if its a tranny or engine problem when its doing it?Thanks again for your help...
Old 03-07-04, 05:27 AM
Join Date: Jun 2002
Location: Long Island, NY
Posts: 1,531
You definitely have a Torque convertor clutch shudder. Theres no doubt in my mind, when you described the vibration for a few secs at 40 mph and 1500 rpm. Can also feel like going over a metal grate such as a draw bridge or riding over the "wake-up" strips on the side of the hi-way. That would be the correct time the convertor would lock-up for your truck with a 3.55 rear ratio.

Going back a couple of years ago take 2 identical models and the only differences were one was std trans and the other was auto. The std trans would always get much better mpg. Thats because the auto trans with the torque convertor always had approx 8% slip all the time.

Today auto trans torque convertors have a clutch built in that can lock the unit and eliminate the slip. When thats applied your in "Lock-up". In your truck it only occurs after it shifts into OD. Usually right after the OD shift, not at the exact shift point.

I believe in taking care of the obvious....if it corrects both be happy....but you have to start some where.

A complete fluid change should take care of the Torque convertor shudder.

Last edited by toyotaman11769; 03-07-04 at 10:46 AM.
Old 03-07-04, 12:26 PM
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like i said desi these are my GUESSES.if im wrong im wrong..them was the first 2 things came to mind right then

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