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-   -   Jeep is "bucking" when stopped HELP (http://www.jeepgarage.org/f77/jeep-is-bucking-when-stopped-help-22062.html)

jcostri09 04-20-2011 03:50 PM

Jeep is "bucking" when stopped HELP
 
The jeep is a 2005 4.7 with QDII

When stopped the RPMs drop and sometimes stalls, also feels like it is bucking at a stopped position.

This problem only happens when the jeep is in gear, if it is in neutral there is no rpm problem or bucking sensation.

A mechanic I had look at it wants to "grease the splines and replace the rear shocks" He says it may be the rear drive shaft and lubing the slip splines may help. otherwise the connection point of the rear drive shaft may be bad. He says there are better replacement parts available, but it would be a big job.

Now, I'm no mechanic, which may be why I have no idea what he is talking about... But its not something i've ever heard of before..


Any suggestions or advice?

jcostri09 04-21-2011 09:06 AM

Re: Jeep is "bucking" when stopped HELP
 
nobody??

TJcust 04-21-2011 09:18 AM

Re: Jeep is "bucking" when stopped HELP
 
I am no mechanic either.. but sounds like the clutch isnt fully disengauging..

I don't wanna tell you that since its a much bigger job than simply replacing the rear shocks and drive shaft, but that would be my first guess specially since it works fine in neutral.

how many Miles/Km?

I would get a second oppinion and run my theory across your mechanic.

jlewissystem 04-21-2011 09:19 AM

Re: Jeep is "bucking" when stopped HELP
 
I had something similar going on, but has seem to subside by itself. For Me: it started after i did my 60K maint, by myself. Nothing crazy, just typical fluids and cleaned the back of the TB - didnt think any of that would cause it. I still get some urge to stall at a red light (stopping) but it hasnt done it. Maybe ask the guy that volunteered in this thread. Good luck! I'm going to follow along for any advice :)

Update: I changed my EGR, due to the issue still occurring. I'm not really sure if my issue is better and here is why (pretty weak suspected reason :) ) When I think about the stall at a light, it actually happens. WHen i dont think of it.....never 1 drop of RPM.....maybe you can will your issue away. I'm still monitoring for troubleshooting.....i have not tried to get a code yet though...

amw5 04-21-2011 11:17 AM

Re: Jeep is "bucking" when stopped HELP
 
It sounds like your idle air is messed up. Have you ever cleaned your throttle body? Check sensor connections, vaccum lines, etc. It could also be your PCV valve. All those things would effect your idle.

Scottina06 04-21-2011 11:38 AM

Re: Jeep is "bucking" when stopped HELP
 
EGR valve

Frango100 04-21-2011 12:36 PM

Re: Jeep is "bucking" when stopped HELP
 
What do you mean with "bucking"? Is only the idle going down too much (until it stalls), or does it feel that the torque converter is not disengaging? Did you already check for any fault codes?

jcostri09 04-21-2011 07:38 PM

Re: Jeep is "bucking" when stopped HELP
 
Its hard to say. The RPMs are definitely affected, but there is a clunk coming from the back at the same time. I agree that it sounds EGR PCV related, but at the same time the clunk has me thrown off.

jcostri09 04-24-2011 10:06 AM

Re: Jeep is "bucking" when stopped HELP
 
Jeep is back... Mechanic greased something... and replaced the rear shocks. Still having problems. Probably taking it in to the dealer this week.

TJcust 04-26-2011 12:14 PM

Re: Jeep is "bucking" when stopped HELP
 
Quote:

Originally Posted by jcostri09 (Post 402130)
Jeep is back... Mechanic greased something... and replaced the rear shocks. Still having problems. Probably taking it in to the dealer this week.


Bad Mechanic.. I hate when they do work and don't even fix the problem. I would change that valve Scott was talking about.

2005JGC 04-27-2011 01:56 PM

Re: Jeep is "bucking" when stopped HELP
 
Quote:

Originally Posted by Scottina06 (Post 400469)
EGR valve

This!

if the egr valve sticks open it dumps inert gas into the intake, which while your driving is not an issue, as thats when its programmed to allow egr flow. You should never have egr flow at idle. A quick (sorta) test would be to loosen the pipe on the egr valve enough to get it out of the intake manifold and cap the now large hole in the manifold. Start it, if it runs much smoother you know your egr valve is sticking.

Also a VERY common problem for idle issues on the 4.7 is the Throttle position sensor. If you grab the connector on the TPS (while its still connected, vehicle running) and wiggle it, if your idle freaks out you need a new TPS.

magnumman426 05-17-2011 08:05 PM

Re: Jeep is "bucking" when stopped HELP
 
Sounds lie a torque convertor problem. Also, and this is just a possibility, there may be a crack in the sump pick-up/filter for the trans, allowing air to be ingested by the converter. Those would be my first suspects, if there are no codes. if you have any dtc's, please send them to me and I will research the condition.


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