steelblitzkrieg

2008 Jeep Patriot 5spd Manual (12,000 miles)

I've been posting this on a Jeep Patriot forum with no results, not enough members.

A few months ago on trips that were at minimum 40 miles or longer very intermittently the vehicle would stutter/jerk, almost like it was stalling.

It only happened at 68-73mph with it in gear, feels like a stall then restart due to the clutch being engaged.

I took her in and the Dealer couldn't duplicate the problem (Because it was trips longer than 40 miles) The Flashed it and hoped for the best, no codes were set.

For the next month she was fine, no issues, but I hadn't gone a trip longer than 40 miles.

Last week I drove home 23 miles, then immediately drove back to Martinez 25 miles, about halfway to Martinez she stuttered again...Same speed range 68-73mph.

This week she started doing it on my commute home (Less than 40 miles) and she started doing it at any/all speeds. It seemed more pronounced just after shifting which was different than all other times. Within 5 miles she stuttered probably 10-15 times.

Yesterday I drove my truck and my wife drove the Jeep, she said she thinks it only happened once to her, but it was so subtle that she may be wrong.

Today we drove her to work and about 15 miles in she started doing it again on the freeway.

Here's my recap of the symptoms....

Any speed stuttering.
RPM's drop anywhere from 200-500 before kicking back up.
Vehicle jerks when it occurs.
Only happens when in gear.

I think it's a transmission fluid pressure issue, this is why...

When the RPM's drop, it is in gear and moving, because of this the RPM's can only slowly drop as vehicle slows. The RPM's can't drop 500 in 1 second while traveling 70mph with the Transmission engaged.

DmaxEter

The link between the manual transmission and the engine is solid. No fluid coupling involved. Even if it has a dual mass flywheel its still a solid mechanical connection. The clutch either locks down like normal or it slips. I dont see the clutch or trans being your issue as you have described.

I would lean more towards an engine issue. Ignition system or throtle position sensor or engine speed sensor or something like that.

steelblitzkrieg

That was the only thing that made sense to me and now you've destroyed that. I hope you're happy.

I'm trying to wrap my head around what would allow an RPM drop with the Tranny engaged and key on. Even if the engine died, wouldn't the tranny force the RPM's to remain at the pre-stutter level as long as the key was on?

The gauges would have to be receiving a signal of RPM decrease even though it's not decreasing really.

No other gauges are effected at all.

Jeff in TD

It's under warranty I assume?

If it only does it after 40+ mile trip, I'd go drive 40 miles, and swing back by the dealer and ask to take the technician for a ride. Maybe he or she will also hook a portable computer to it, so as to read what's going on when the problem happens...

I'd also say it is an engine problem of some sort, apparently heat related? but if it's under warranty I'd focus on being able to show the dealer's mechanic what the problem is- and from there it's someone else's problem to fix.

steelblitzkrieg

Now it does it even before the 40 miles, it is warranty.

I was tempted to pull into the dealer today on my way to work, but I was already running late.

I think the Data recorder is going to be the way to go.

irocpractice

Pick up mechanic on way to work and have them drive it back to dealership.

AlpineRAM

I think that you've got some electronic problem- the engine control module loses an important input (eg crank position) and stops injecting/firing , engine stutters, and also "informs" the dash that "rpm=0" - so the needle drops, the sensor gets back to work, engine control module injects/fires , sends "rpm=3133" to dash and everything is back to normal.
While the problem occurs the tach is ordered to go to 0 , so it will dip down. With the manual tranny the engine can't change it's speed without changing the vehicle speed by the same proportion unless the clutch is disengaged.

HTH

AlpineRAM

scottsjeeprolet

I can't help you with your problem but here is a good site.
Jeepforum.com

steelblitzkrieg

Tried that one a while back, thanks though.

On a side note directed at you Scottsjeeprolet, on a Jeep Wrangler can you adapt/change out the rear seat to sit 3 kids (3 belts?) I want to get a wrangler for a toy when camping but we have 3 kids...11...10...4yrs.

If not I may have to look into an old Bronco or Scout, but I'd rather have a Wrangler.

Another option may be putting a bench or 40-20-40 in the front?

DmaxEter

Check this out for your seat question.

http://jeepsunlimited.com/forums/sho...d.php?t=499513

steelblitzkrieg

Thanks, that was very helpful.

DMH

I had something similiar happen to me a few years ago with a 1990 Plymouth Voyager my wife drove. It seemed like everytime we went on a trip with it, it would "stutter" every so often. I had a mechanic friend with a portable computer ride with me one time and, of course, it never happend. It was really driving me nuts.

Finally, I replaced the alternator, and that fixed the problem. There must have been something in the alternator that was shorting out momentarily that was causing it. Of course, having the alternator checked never worked, because it was so intermittent.

That is how I fixed mine.

DMH

steelblitzkrieg

Any Gasser techs know where I could find a software program for my Laptop so I can data log the vehicle myself? Dealer doesn't seem very helpful.

It's the Patriot in my sig.