Well, I finally parted with my trust locked and lifted YJ for a great deal on a used 08 JK. Having skipped the TJ years (for lack of money), the new JK brings a lot of pleasant surprises... like HVAC that actually works.

I'm having some odd symptoms, though, with the new JK. From a standing start, you have to give it a healthly amount of gas to get it going (rev to around 2500 RPM). Much less than that and it lugs, sputters, and dies. (I've driven manual tramsmissions for the last 15 years, and this is the touchiest one I've seen. With the old YJ, I could let out the clutch without hitting the gas, and it would start rolling.) Unless I'm careful when starting out, especially on an incline, I'm likely to stall it. Also, when moving at speed and hitting the gas hard at around 2000 RPM, the JK seems to have a faint hesitation and stutter before it kicks in and starts to accelerate.

My question is, has anyone else experienced this? I read about the stall bug in the 07's, and this doesn't seem to fit.

I know that going from my relatively light-weight YJ to a 4-door Rubi is a pretty substantial increase in weight, so I don't expect it to be a rocket. But, it is a bit more sluggish than I expected. I'd done some work to my old 4.0L six -- header, new ignition, K&N intake system, etc., all external mods -- and so it was a bit healthier than your stock 4.0L. But the V6 performance of the new JK just seems a bit off.

Outside of that, I just love the new Jeep, though I'm still sad to have parted with the YJ. At least it has a good home.

 

I've stalled mine many times. It's the way the electronic throttle control works. I wish I had some idea of the logic behind it so I could work around it. Is yours auto or manual? I have the six speed, and I've found I have to get the revs up a little (not 2500 though) before I start letting the clutch out. In the past on other vehicles I've always started letting the clutch out and when I felt it start to grab I'd give it some gas. That approach doesn't work very well and usually results in me stalling it because the engine doesn't respond immediately when you stab the gas pedal. A friend has an automatic and he really doesn't like the throttle response (or lack of it).

 

Between the drive by wire throttle, and the fact that the 3.8 V6 has about as much torque as a civic at idle, I have stalled mine more times than I can count. Its the single largest thing that I dislike about this Jeep compared to my others.

I have never had to rev it to 2500 though. Something is certainly up with yours. I would have it checked out.

 

I find the need to blip the throttle at times to get mine moving; but not to 2500rpm.. You will get used to it over time, I have 21k on my 08, and you do have to pay attention at times to get off the line smoothly...

 

In retrospect, 2500 rpm seems to be a bit of an exaggeration. It is probably closer to the 1200-1500 RPM range.

It just seems that the revs need to be higher in general on the V6. I typically shifted the YJ at 2200 RPM, but I find that the new one need to be wrapped up a bit higher.

Thanks for weighing in! Just glad to know I'm not too crazy. I mean, aside from owning a Jeep in NYC...

 

The JK with manual is really different from the feel of our TJ with the straight six and cable throttle.

Like others have said... I stalled mine, even driving it home from the dealer. Then my son stalled it twice the first time he drove mine. (He now has the TJ).

You'll have to give it a little more throttle, a little sooner with the Drive-by-Wire. The power/torque curves say the 3.8 is same or better than the 4.0... but it sure does not feel like it until it revs up past 1500 anyway.

All that said, I agree with the others, you should not have to go to 2500 to get going... maybe 1200-1500.... I'll try to pay attention next time I jump in there.

Maybe a trip to the dealer is in order if it's that bad. Also, is your clutch excessively 'grabby', like it's glazed or burnt, or wet from a slave cylinder leak?

 

X2 on what others said. It between the throttle by wire hestation and the lack of any low end @ idle. If you are REALLLY slow on letting up the clutch you can get it to run on idle in first but with RubyDoo i usually just kind of burp the throttle to get going. Guessing that you have the stock 4.10 gears and the stock 32's it should get and go ok.

 

Well the 4.0L makes a lot more torque in the low end. Any V type engine you have to rev a bit more than an inline block.

 

Both things you are experiencing are normal...


I've driven manuals all my life. I had not stalled one for probably 20 years. I stalled the JK about 10 times in the first 2 weeks I owned it.

The clutch engagement seems a little inconsistent. It seems like some times the material is really grabby and some times it slips more. That and the fly-by-wire throttle also seems inconsistent. Those things combined make it by far the hardest manual I've ever driver. I've had mine for about 8 months now and I will still occasionally bog it to the point of nearly stalling or go the other way and end up giving it too many revs for a normal engagement.

The bog you feel after a shift is also normal. Oddly enough every time the shop has worked on my jeep the bog is gone when I get it back and it seems to come back over time. I'm guessing they pull the battery cables to work on it which resets the computer and then over time as the fueling tables are learned the bog comes back. If you want to see, pull your batter cables for a minute to reset your computer and see if you bog goes away.


Another thing I noticed is that the jeep really fools people into choosing really low shift points. I think that because there is a lot of engine noise that can be heard in the interior and the engine really doesn't love to rev, that people are shifting it really low. I looked up the recommended shift points in the manual (which are typically very conservative). They are given in miles per hour. I converted them to RPM based on my gearing and tires. For my stock Rubicon with 4.10s I calculated them to be somethings like below (I don't remember them exactly but these are close)....

1st -> 2nd 2,900
2nd -> 3rd 2,700
3rd -> 4th 2,500
...


Using those shift points I very rarely get a bog.

 

Thanks, all... it has been reassuring that I'm not the only one feeling bogged down. At my current rate of savings, I should be able to afford the hemi conversion is about 8 years... maybe I'll have learned to not stall it by then.