No power below 2000RPM 5.7 xk

[thance]

I'm having an issue where I don't get enough power to the wheels to move forward until about 2000 RPM. This is way above normal and is happening once the jeep is fully warmed up (after say 20mi of driving when I come back off the highway and have some around town driving).

Things I've noticed so far are, for instance, at a stop light I will hit the gas normally and nothing will happen. Then I hit it harder and it jerks forward, so I let off - nothing - hit it again jerk faster..... this can happen until I get up to speed, 50mph or so.

Another instance was stopped at my mail box. Went to proceed up the driveway and had to rev to 2000 RPM to get moving. The driveway is a slight slope, Not steep at all.

Any ideas?

I'm thinking clutch pack in the x-fer case or torque converter if it's mechanical.

The engine does not appear to be having issues. Runs smooth. No stalling. So I don't think it is an issue. Though I did once have a car with a worn out cam shaft that had next to no power - cam shaft lobes were warn off, nice and round.

I would say the clutch was warn out if it had one.......

[07JeepXK]

Does your transmission fluid smell burnt? When was the last time you serviced the transmission and transfer case??

[Matt]

Try putting it in 4low and see if it still happens

[thance]

this is a 2010 with 65,000 mi on it. I have not changed transmission or transfer case fluids.

Transmission fluid still looks new, didn't smell it.

Haven't opened the xfer case.

Could changing the fluids solve this issue?

[Matt]

Probably not. But see if we can rule things out by trying it with the tcase locked.

[07JeepXK]

You need to swap the fluid regardless on transfer case if it has 60,000 miles on it and never been changed. Try what Matt said with transfer case locked

[thance]

I'll check 4lo when I get home from work. Took the wife's libby today so mine wouldn't get any worse. I never had any issues in the Bronco with tcase or diff fluid and that was up to 170,000 mi. But, no limited slip or clutch packs in either, so it was quite different. (don't have clutch packs in the xk diffs as it is QT2, but the t-case likely does).

If it does work in 4lo after I drive it long enough to exhibit the problem could a fluid change fix it or are the clutch packs shot?

[Matt]

Dont drive it around too long in 4-low. Drive around in normal 4-hi until the issue starts, then shift into 4-low and see if anything changes.

If it does work in 4-low, you may just need the clutch packs rebuilt.

[thance]

Dont drive it around too long in 4-low. Drive around in normal 4-hi until the issue starts, then shift into 4-low and see if anything changes.


That's my intent.

Thanks!

[thance]

Test drove yesterday evening and to and from work today (35mi each way) and can't reproduce the issue......

[Matt]

I'd drop the trans pan and replace the filters for good measure. Could have a faulty/damaged filters thats intermittently restricting pressure. And at 65k+ miles, consider it good preventative maintenance regardless.

[thance]

I think its time to replace all my driveline fluids.

Friday was really hot, so that may of played into it.

Also I had an electronic pressure booster on the trans that I removed Sunday. That had been on for months, but maybe the hot weather helped it trigger something. Not sure....

Also removed the diablo tune for good measure.

[06JeepXKHEMI]

Which diablo tune did you have installed? Since I've removed my performance transmission tune I haven't gotten that trans over temp signal.. I've read a lot of Chrysler's transmissions or at least their electronics don't like tunes, so change fluids and remove tune, see what happens..

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[thance]

I have not seen a trans temp light/signal but maybe that's a difference between the 06 and 2010. I also have not seen a performance transmission tune from diablo. I was most recently using the mileage tune when I started having this issue of no power/surging on hills and from a stop. It was intermittent but at it's worst last Friday. May have something to do with the heat wave we were having.

Could you send a screenshot/pic of the trans tune option?

I was using a separate jumper that I believe played with the input signal to the trans, fooling it so it would run higher pressure and shift harder. I very rarely noticed any noticeably hard shifts (only a few times and not when you would expect it) so not even sure if this was doing anything or working right.

I had a similar module from B&M on my Bronco that had a switch for stage1/stage2/stock. This worked great with stage 1 being comfortably firm and where I would keep it for daily driving and stage 2 sending shutters through the driveline. I only used stage 2 occasionally for fun. I was expecting something similar with the Commander, but not sure it was doing anything productive. Also, not sure that it was related to the issue over the last couple of weeks as it was on the vehicle for months.

[06JeepXKHEMI]

The message I was getting may not be cause of the transmission tune but a totally different reason, I just removed it to rule that out. I knew when I was researching that its not advised to mess with the electronics on the transmission but ran into no issues, until now which like I said may have nothing to do with it.

My opinion would remove any modification with the transmission and change driveline fluids to rule out obvious and easily fixable items. Ive heard about that module and it does nearly the same thing as the tune does but i change shift points, firmness, redline, throttle boast, etc, needless to say I can chirp the MTRs hitting 2nd gear, this is not advised and not what our transmission were designed to do!! hahaha

[thance]

Took it to the dealer end of last week and they said it was do to the tire size :)

On the bright side they fixed a PO131 code I've been getting religiously for quite some time and 2 TPM sensors I had replaced with rubber valve stems.

They changed an O2 sensor to clear the code, but I think this was just to have something to charge for as I had done this to no avail and the code points to a ground issue.

I changed Trans fluid on Sunday and in combination with the dealer visit, my mpg has jumped from about 12.5 to 16.5...... seems a little extreme.

The original issue in the post has not come back in 1 wk now so I am hoping it is gone for good, but we'll see.

I will also be changing diff and tcase fluid in the near future, didn't get to them this week as I found the front diff has drain and fill plugs, but requires a 14mm hex key .... not common for a shade-tree mech; and the t-case is similar with a 12mm hex required. My "free" hex keys that pump the tool count in larger sets only goes to 8mm :(

[1USMC]

Took it to the dealer end of last week and they said it was do to the tire size :)


Any more amplifying information about the tire size ? Are they all worn to extreme differences and/or are you using dissimilar brands/sizes ??

Did you do anything to correct the tire size problem the dealer told you about or do you doubt there analysis ?

[06JeepXKHEMI]

Yea what tires are you running? I have never had any loss of power the my 57lb a piece MTRs and I know Adam whose running 33 MTRs doesnt have any issues like you had..

[thance]

I think they saw a modded jeep and didn't want to deal with it. The tires are new (~5000mi) 265/70-17 General Grabber AT. This is a sporadic issue that was happening on hills and from a stop. Hot weather may have contributed as well (not sure). They were unable to reproduce the problem and pointed to another lifted jeep that had a similar issue.

I will add, that in addition to the better gas mileage, power seems to be better in general since the trans fluid change yesterday...... this is a seat of the pants observation and I have no idea why it would be related, especially given that the old fluid still looked new, so take it for what its worth.

[thance]

Yea what tires are you running? I have never had any loss of power the my 57lb a piece MTRs and I know Adam whose running 33 MTRs doesnt have any issues like you had..

The extreme and sporadic loss of power that prompted the thread, I doubt tire weight would be an issue, or the size for that matter.

I have used the diablo to adjust the tire size, though it gives no clear indication it works properly (does not save / recall the new setting in a viewable manner) I think the speedo was accurate.

[1USMC]

The extreme and sporadic loss of power that prompted the thread, I doubt tire weight would be an issue, or the size for that matter.



If the tires are all the same size..... Ya.... that was what I was hinting at .