hesitation while accelerating under heavy load

[bruinsfan]

I have a 2007 xlt rwd explorer (4.0) that is pretty well kept.

I am at 100,000 miles and noticed a slight studder or hesitation in the engine while climbing up a small hill with a heavier than normal load (not over loaded though).

The explorer seems to hesitate when giving it gas to get up the hill.... but not all the time. The trans was serviced and runs smooth.

The obvious fix to me is the TPS. Is this an easy part to just unscrew and replace? It look like it....as long as I heat up the old screws to untighten them..

What else could it be (coil pack, MAF, ) ......and do you guys recommend changing out any fuel/air parts at this point as preventative maintenance with 100,000 miles on the truck?

 

[thebrakeman]

Sounds like a misfire.Have you changed the plugs yet?
See if there are any pending codes that can be read at an autoparts store.

 

[bruinsfan]

the plugs only have 30,000 miles on them.... should be good still (I hope)

The plugs and wires were changed but I didn't change the ignition coil....

 

[Davidm53]

Start with a new Fuel Filter if it has not been changed already.
Seafoam would be something to try also.

 

[Flag Gibby]

I don't recommend Seafoam on a vehicle with only 100k miles. My question is what are the engine RPM's when it does it? Vehicle trying to decide to downshift or not? As far as the MAF or throttle body, I would just start by cleaning them; on the 4.0 they are most likely not the issue. You can also hook up a code reader and monitor the vehicle parameters while you drive that section of road to see what the load on the vehicle engine etc. is to help establish what component may be the culprit.
The only thing that you haven't done yet that is almost due in terms of preventative maintenance (PM) is the PCV valve so if you want to you can change that too and cross it off your PM list.

 

[bruinsfan]

I don't recommend Seafoam on a vehicle with only 100k miles. My question is what are the engine RPM's when it does it? Vehicle trying to decide to downshift or not? As far as the MAF or throttle body, I would just start by cleaning them; on the 4.0 they are most likely not the issue. You can also hook up a code reader and monitor the vehicle parameters while you drive that section of road to see what the load on the vehicle engine etc. is to help establish what component may be the culprit.
The only thing that you haven't done yet that is almost due in terms of preventative maintenance (PM) is the PCV valve so if you want to you can change that too and cross it off your PM list.

Thanks for the advice....

I can't duplicate the hesitation if I wanted to... I get no warning lights or codes.

The rpm's didn't jump eradically when this happened and I think they were around 1700-2000. I starting to think that I caught the engine at an awkward time around a shift or down shift and the injectors wouldn't allow the fuel to pass.

Either way, I'm changing the fuel filter and PCV valve. Perhaps a bottle of Amsoil PI....

 

[Davidm53]

Seafoam has a spray version that is good for cleaning intakes while the engine is running.

The regular version goes in the tank or can be sucked into the engine by a vacuum line.

 

[Flag Gibby]

Either way, I'm changing the fuel filter and PCV valve. Perhaps a bottle of Amsoil PI....

Not a bad idea to start with those items. The fuel filters are due every 30k miles and worth every penny in my mind (a pain to change out, but worth it). I waited too long to change out a fuel filter one time (only 38k on the filter) and didn't realize how much I was starving the cylinders. My fuel economy was getting really good but I ended up burning all the platinum plugs on cylinders 4-6 because I did some long heavy towing trips with it that way.
I would wait on the Amisol to see how the other items fare first and then, if you still want to, run it through the system. Otherwise you won't know what fixed the issue.

 

[bruinsfan]

Thx Flag Gibby.........

I've also noticed that the Motorcraft plug wires also have a hard time staying "clipped" to the ignition coil. I've had to use plastic secure ties to keep the "clip" tight and secure on the coil...

I haven't changed the ignition coil yet.... I guess thats probably going to fault sooner or later.