Engine hesitates with temperature change...

[767flyr]

I have a 2001, 4.0, 4WD, Ranger, 78K miles. The engine hesitates while driving around 55-65mph when the temperature is in the 35-40 degree range (these are the speeds I notice it most...it has done it at slower speeds as well). With a constant throttle setting, while crusing down the interstate, it will miss or hesitate like it is going to quit, only for a second, and then it will run fine for a while, like a mile or two or three. As long as I am accelerating it runs fine.

But...it does not always do this. It started last winter. As it seems to be temperature related. When the temp is around 35-40 (more or less) it will hesitate...although, not always. Once the temps warmed up for the spring and summer, I had no problems. But now that winter is here and passing through the 35-40 degree range, it is starting the hesitation again.

There are no codes set.

I took it to the Ford garage, but of course it was not acting up as the temp was in the 20's that day and they could not or would not give me any clues as to what the trouble might be related to.

Since it seems to be temp related, is that a function of the MAF sensor? Or is there another sensor that measures temperature that could be failing? Or should I be looking at something else?

Any suggestions would be appreciated.

Dave

 

[Tbars4]

...welcome here...
...i could guess at a couple things but if it is intermittent, i would just be guessing...:scratch:
...since it is the holidays and most are with family and friends, you might have to wait for more help...merry xmas...

 

[beachguy]

perhaps a short in the fuel relay

 

[767flyr]

Beachguy,

Fuel relay didn't even cross my mind as a problem...that should be a low cost part to try.

I did clean the MAF sensor, it had a rough idle along with the occasional hesitation, the cleaning took care of the rough idle and it has not hesitated (as of yet) since. But it is an intermittent problem so we will see.

Thanks for your input, it is appreciated.

Dave~

 

[nu.b1]

Just guessing..

Have you changed fuel filter? Cleaned IAC? Just guessing... good luck and let us know what you find please..

 

[767flyr]

Nu.b1

I plan to change the fuel filter as I am sure it could use a new one. I have not cleaned the IAC. I did clean the MAF and so far the hesitation has not come back. The problem is intermittent and temp related so I am keeping my fingers crossed the MAF cleaning may have taken care of it. I want to give it some time to resurface (or not) so hopefully I can isolate the cause with some certainty, then what ever it turns out to be I will post it for others that may come across something similar.

Thanks for your input, it is appreciated.

Dave~