feels like its being held back

[rosgood]

My 2007 Liberty has the 3.7 engine and is 4 wheel drive. Over the last few months the jeep feels like it is being held back by something. I need to put more foot into the gas to make it maintain normal speed (like 55). It likes to settle in at a speed of around 45 mph. No miss-fires, it starts fine, idles fine just no guts. Before I do a shotgun approach, I was hoping for some help on a priority list of things to try. Here is what I have done so far:

1) New plugs
2) Check for codes - none
3) Check transmission fluid level - good
4) Ran fuel system cleaner through it

Thanks in advance

 

[ftaa]

plugs wont do anything untill the MIL comes on .... sounds like a re-learn may be in order. try pulling the battery post and standing on the brake for 30 seconds ... reconnect battery terminal drive it around for a bit.,

 

[uss2defiant]

When's the last time you serviced your ******?

 

[rosgood]

When's the last time you serviced your ******?

Thanks for the reply. I have never serviced it. Only check the level and color. that was about 2 months ago and it looked good (as far as I could tell). What else should I check regarding the transmission?

 

[tommudd]

Check brakes see if any calipers sticking
What plugs did you use ?
When did you last change diff and transfer case fluids
Tire pressure
Number of things that could explain power loss
But try knocking a few of the easy ones out first

And you only check transmission fluid every 2 months??? Wow
Oil, trans fluid, PS fluid, air pressure, coolant etc checked at the very least weekly

 

[rosgood]

Check brakes see if any calipers sticking
What plugs did you use ?
When did you last change diff and transfer case fluids
Tire pressure
Number of things that could explain power loss
But try knocking a few of the easy ones out first

And you only check transmission fluid every 2 months??? Wow
Oil, trans fluid, PS fluid, air pressure, coolant etc checked at the very least weekly

I will check the brakes. Tire pressure is good. I have never changed the diff case fluids. I will put that on the list. Plugs are AC (I believe)

Thanks

 

[megatone]

My buddy has a 2006 Chevy 2500HD truck and his rig started doing the same thing a few months back. Eventually the acceleration problem became worse. It got to the point where at slow speed while making a sharp turn (at an intersection for example) the truck would want to come to a complete stop. Almost as if the brakes were being applied. What the problem turned out to be was that the ring & pinion gears were bad. I know Jeep and GM are two different animals, but possibly the limited slip design is the same (I don't know). But it's worth a look. Basically the problem was the rear differential components: the limited slip mechanism and the ring & pinion gears, the bearings.....everything. The repair required the rear differential assembly to be completely rebuilt. The total cost was $3,200 Parts/Labor with all new components. Additional cost was $300 for a new aluminum drive shaft (to replace the twisted one) and about $30 for universal joints (to replace the ones that lost thier grease due to friction & heat build up).

A shop tech mentioned that upon initial inspection of the differential, he noticed that the gear oil was really thin.....lighter than light weight engine oil. He said it was nowhere near the thickness of gear oil.

 

[libertybob]

No power....

Check the fuel pressure and fuel volume flow. I had a Chevy S-10 that lost power due to fuel starvation as the fuel pump was failing. Replaced the fuel pump and all was well.

 

[rosgood]

Thanks all. I have a local mechanic coming to take a look tomorrow morning.

 

[megatone]

Be sure to update, please.

 

[rosgood]

Update - Mechanic changed rear diff fluid (very dirty and sludgy). He also changed the front fluid which seemed to be old but not bad. I will drive it a few days to see if that was the issue. Feels better in initial rides.

 

[rosgood]

Update - after 2 days of driving I no longer feel the hesitation or holdback. I am going to mark this as fixed.

 

[TwoBobsKJ]

Update - after 2 days of driving I no longer feel the hesitation or holdback. I am going to mark this as fixed.

You've given a good testimonial for regular maintenance :waytogo:

May be a good idea to have the gear oil changed again in a couple thousand miles. If the old stuff was that bad there is probably oil gunk and sludge in the axle tubes and outer bearings that's being flushed out by the new oil. Changing the diff oil again after a short while will get rid of the crud that's now mixing with the new oil.

Bob

 

[profdlp]

^^ What he said.

Just for future reference, you can buy a gallon of gear oil for $15 and do both ends in very little time. I don't know what your mechanic charged you but it was probably more than that.