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Matt, Engineer
Category: Jeep
Satisfied Customers: 21726
Experience:  Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
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My 2005 liberty renegade, 2wd, 3.7 automatic (vin

Customer Question

My 2005 liberty renegade, 2wd, 3.7 automatic (vin 1J4GK38K85W503418) experiences a noticeable momentary"shudder" (as though the back tires were skipping on the road surface) in the rear when driven. This occurs randomly at various speeds, rpms, road conditions, accelerating or slowing down. The input and output speed sensors on the transmission have been replaced (also the rear center speed sensor). The transmission had the filter replaced and the fluid flushed and refilled. The internal solenoid pack has been replaced. No codes are present. What could be causing this?
Submitted: 1 year ago.
Category: Jeep
Customer: replied 1 year ago.
Also, the old fluid was clean, no metal in the pan or on the magnet.
Customer: replied 1 year ago.
App. 148k---no previous transmission issues.
Customer: replied 1 year ago.
No metal found in old fluid, in the pan or around the magnet.
Expert:  Ron replied 1 year ago.

Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

Unfortunately with the amount of miles you have on this transmission you are likely looking at an internal transmission concern, you need to start with testing the clutch volume indexes with a scan tool. See the values in the link below, copy and paste the link to your browser to open and view them.

Customer: replied 1 year ago.
Ron, thank you for your response. While I do not have an advanced scan tool available (I'm remotely located), I did contact the last mechanic to work on the Jeep (a couple of month back before departing on an extended trip) who, upon questioning, revealed he had cleared a P0740 code which did not reset. Since I have no way to ck volumes as you suggested, what can I do myself to further narrow the source of the problem. I have a decent set of hand tools and was a fair "shade tree" mechanic before cars grew so sophisticated specialized tools and knowledge were needed. Please provide the info needed for me to repair this myself.
Expert:  Ron replied 1 year ago.

Unfortunately the next step is going to need to be checking the values, I'm afraid with the amount of miles you have on the transmission you are likely looking at a replacement and or rebuild in the near future.

Customer: replied 1 year ago.
What you've told me is to take it in to a shop for an answer to the issue. I've described. Since I explained this isn't possible, your answer is not helpful. Again, isn't there something else I can do myself---this is why I asked for help, not to be told for me to ask someone else. There must be something else you suggest based on what I've described. Please try again.
Expert:  Ron replied 1 year ago.

I will open the question back up for you in hopes someone else has something new to offer. If they do, they will respond.

Expert:  Matt replied 1 year ago.


something else to consider is that this could be an engine fault ?

This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.

As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine

Customer: replied 1 year ago.
Matt, thank you for your suggestion. I'm in the field presently and will troubleshoot for air leaks when I return. It does seem when I feel the rear wheels begin to "shudder" if I let off the gas, it will stop. Does that behavior agree with your idea?
Expert:  Matt replied 1 year ago.


yes that matchs with an air leak scenario

let me know what you find

Expert:  Matt replied 1 year ago.


do you still need help?

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