Sluggish at 50mph

Beckon · **Joined:** Mon Jun 28, 2010 8:45 pm **Posts:** 15

Greetings all, I'm new here..well sort of? (moved to an XJ forum after my liberty was sold years ago)

I have a 2011 Nitro 3.7 but those forums are pretty dead so I'm harassing you now

Anyways..I have 80k on the car and at around 50-55 mph it dogs down on power until i get the RPMS back up or hit the next gear. no CEL's, plugs are good, AFR looks fine and fluid is good. It simply feels like the car is so low in the RPM's that it's just chugging along at that point. You can feel it sort of..vibrate only thing i haven't considered is the TPS :roll:

So question. Is the 3.7/42RLE just struggling that much in these little guys? I've tried searching for similar issues with no luck.
Thought i'd ask just in case this is a sign of a deeper issue or if it's "normal"

I'd like to think i have illustrated my question and issue with enough details.

Thanks

lfhoward · **Posted:** Sun Nov 20, 2016 9:41 pm

Welcome to the other side! Actually we have a few KA's on here. Scar0 comes to mind and he is still active.

What you describe sounds like a symptom in early year KK's that Jeep fixed with a computer flash to adjust the shift points. Here is a link to the technical service bulletins. Have a look to see if what you're describing is on there.

http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=104&t=39066

Scar0 · **Posted:** Mon Nov 21, 2016 8:33 am

Yep I'm still around when I can get connected to LOST. This web site is so slow it's like pulling teeth to get a thread open...
Anyway, The aforementioned TSB does come to mind. However, since you have a 2011 it would not apply.
Do a reset. Disconnect the Neg(-) battery cable for 10 minutes. This not only resets the computers, it also puts the trany in learn mode.
After you connect the battery back up, drive it like you stole it for a while.
What plugs are you running? No platinum in a 3.7 KA! They only cause problems.
I use NGK ZFR6F-11G plugs changed every 30k.
You can also manually wipe down the TB. Open it with a finger when the rig is not running. Then start the rig and spray some cleaner in the TB. Next, spray some into the booster side of the brake booster vacuum hose. Pinch off the hose between squirts to prevent over rev and running to lean.
At least then you know the TB and intake are cleaner then they were.

Beckon · **Joined:** Mon Jun 28, 2010 8:45 pm **Posts:** 15

Scar, I will give that a shot.

As far as plugs, i'm running OEM ZFR6F-11G as you mentioned.

I hopped in the rig yesterday and the issue seems to happen right as it enters the gear range that 50 sits in.

Overall, I snagged the nitro for $9k with 60,xxx miles from a jeep dealer. I can't really complain if that's the only issue I've had in a year

I'll keep you all posted!

Scar0 · **Posted:** Tue Nov 22, 2016 9:26 am

Cool deal.
Yep that is the speed (45-50) when the trany would go into partial lockup, the TSB reprogramming was supposed to fix. I haven't heard of anyone recently with that particular issue lately on the Nitro forum I am a member of.
One other thing to check would be the trany fluid level.

Sluggish at 50mph

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