[clintondean]

This is my 1st 4.0 and I'm wondering if they all are this way. Mine seems to have a real flat feeling spot right after a shift. I can seem to make it go away by getting the rpms up higher before I shift, but it just seems excessive when I run it this way. Just putting around town it seems like a dog at low rpm. It is a 06 X with a six speed....has 3.73 gears with 31" tires so I know it should feel pretty stout. I recently pulled a small pop up 1400# or so and I really had to wrap it up so it wouldn't dog down in the next gear. It's been this way since I bought it with 11 miles on it. I installed a flowmaster and am considering a cold air system to help it breath. Does anyone elses 4.0 feel like this? Thanks for any advice in advance!!

[mdawg4x4]

Haven't pulled anything with mine in a while. The last was a 10' trailer with camping gear for 2 families to the Smokies and back. Had no issues. Have upgraded to 33s now and am still happy with power. 1st, 2nd, and 3rd pull great from 2500 through 3500 rpm.

[Timmah707]

Mine's got over 177,000 miles and pushes 35s around very well after a regear. She's still runnin' like a champ!

[Imped]

I JUST noticed this with my TJ today! I have the I6 and 5 speed with normal 29" and 3.07's, but from 1st to 2nd--unless I give it a fair amount of gas and shift at 3k--it does this after I shift. I feel like it's normal but I would love for it to be a little more continuous. Maybe it's completely normal, maybe not. But, you're not alone! I'd love to figure out what it is. Do you have gear whine as well at slow speeds?

[Red_]

Mine runs like a top. No flat spot.....

[jeep06]

Originally Posted by clintondean

This is my 1st 4.0 and I'm wondering if they all are this way. Mine seems to have a real flat feeling spot right after a shift. I can seem to make it go away by getting the rpms up higher before I shift, but it just seems excessive when I run it this way. Just putting around town it seems like a dog at low rpm. It is a 06 X with a six speed....has 3.73 gears with 31" tires so I know it should feel pretty stout. I recently pulled a small pop up 1400# or so and I really had to wrap it up so it wouldn't dog down in the next gear. It's been this way since I bought it with 11 miles on it. I installed a flowmaster and am considering a cold air system to help it breath. Does anyone elses 4.0 feel like this? Thanks for any advice in advance!!

Mine has a real big dead spot... it has a hesitation especially starting out from a stand still. Real good for jerking some heads if I get my timing off slightly when taking off,,, must be normal on these?? I've done all the routine work on it... air filter, cleaned throttle body,,,wouldn't think it is ready for plugs yet at only 15k mi....but who knows.

[Si1ver03Rubicon]

Those with flat spots after shifts. I'm thinking its a dirty or bad TPS. At least thats what mine is, been throwing the code for a while now. Hopefully cleaning it will help otherwise autozone wants $75 for a new one

[Nonya]

I'll bet its do to emissions,the engine emissions are setup so tight to begin with after a very few miles the flat spots show up.06 would be the worst for this type of thing.Also try different fuel brands or some injection cleaner,I'll bet that 06 is programed so tight to get through Emission standards it squeaks!

[clintondean]

Maybe I just need a power programmer or a stage 1 jet chip......any thoughts?

[Nonya]

Dont waste your money,if you were really interested in having a sweet running jeep find someone with a dyno and tuning software.Then spend 500 dollars and it will be perfect.

[doogie]

This isn't the first time someone has mentioned this. I stepped up from 2 4.0 5 speed Cherokees and they pulled hard from the get go with no noticable drop offs. But as soon as I got my TJ I like you notice the dead spots. I rarely shift above 2,500 rpms and normally shift at 2,000. But I would love to know what the dead spot is. This 05 is the top of my vehicle budget and I need it to last for a good 200,000 and I'd be interested to see if something is actually wrong or if this is just a quirk.

[Zew]

I think on this thread, you're gonna see two things. The people who are totally happy w/ their 4.0 and those who aren't.

I'm not happy w/ mine. It runs like sh1t, has a nasty misfire that i can't get rid of which throws a P300 or P301 code. Because of that I can't pass emissions and therefore my license plate sticker is expired and i can't drive my jeep. I'm in the process of building a stroker. Hopefully it works better than the 4.0.

[BlueFlame]

Mine did that. Sometimes it did it hard enough to jerk like it had shut off for a split second then came back on.

Two things cured it and it has never returned.
One (this is controversial but it really helped) was removing the little intake horn from the air box.
Made a HUGE difference - not in power but in low end pickup and that dead spot.
Also, there's one hill on my morning drive that I had to downshift for, after removing the intake horn I don't have to any more.
The other was a few weeks later changing the oil and putting in a new air filter, even though the one in there was pretty clean. Felt the difference. That took care of it. Mine doesnt' have that dead spot anymore.

Aside from the dead spot, it always pulled strong at the bottom end (top end too) and I couldn't be happier in that respect, I love this engine. Seems to be two separate issues.

[clintondean]

I might try removing that piece and see how it does. I noticed it more after the flowmaster install....like I need to increase air flow in. I'm not getting any codes at this point and it runs really strong at higher rpms. If you get it up between 2500 and 3000 it will pull that pop up trailer up just about any long hill you come across, it's just that driving on flat ground I'm having to rev it high to miss that dang flat spot.

Thanks for all the imput guys....at least I"m not alone.

[FL 4.0L]

My dead spot was eliminated with a new TPS.