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Rough Shut-Down and Random Hesitation
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Author:  richardkf [ Tue Oct 16, 2007 8:11 am ]
Post subject:  Rough Shut-Down and Random Hesitation
Out of the blue, I noticed that every couple of times when I go to accelerate, there is very small split-second choke on the engine and then it accelerates normally. Other times, no hesitation and everything is fine. I also notice it consistently shuts down very rough when I turn off the key.

When accelerating on to the highway, I did about 3 or 4 WOT the past two days and it has reduced the hesitation (not eliminated it), but not the rough shut down.

However, no problems with starting - always cranked about 2 or 3 turns and kicks over - still does. No CEL light and no black smoke unless I am WOT.

I have not read any codes yet. I am guessing this is a dirty map sensor, air filter, egr or fuel filter from what I've been reading. I have 13.5k on the odometer now.

What do you guys think - where should I start? Also, none of those items have ever been changed, at this point. Just oil changes and diff. fluids.

Thanks for your help.
Author:  bugnout [ Tue Oct 16, 2007 10:06 am ]
Post subject: 
The rough shutdown sounds like a gummed up FCV Flow Control Valve.
Author:  richardkf [ Tue Oct 16, 2007 10:33 am ]
Post subject: 
bugnout wrote:
The rough shutdown sounds like a gummed up FCV Flow Control Valve.


Is that something that can be removed and cleaned easily or is it better to get it checked and replaced under warranty?
Author:  LocoCRD [ Tue Oct 16, 2007 11:27 am ]
Post subject: 
It's doable, but not easy. I'd see if they'd do it under warranty. Once you get that fixed up you might concider doing the SEGR mod to hedge future problems too.
Author:  tim wulf [ Wed Oct 17, 2007 9:31 am ]
Post subject: 
Change the air filter. That's easy. Check the FCV by shutting off the jeep and running around to the front of the car and putting your ear close to the hood. within 5 seconds you should here the FCV open back up. It should be a crisp clicking sound if it's clean. If its not working at all you won't hear it and that explains your rough shutdown.

The FCV is open all the time and closes when you shut the engine off. It sprigs back open in about 5 seconds.
Author:  LocoCRD [ Wed Oct 17, 2007 1:49 pm ]
Post subject: 
tim wulf wrote:
The FCV is open all the time and closes when you shut the engine off. It sprigs back open in about 5 seconds.


Not exactly true. The FCV is modulated slightly shut when the EGR opens to let all that crap recirculate into your engine. This is one of the benefits to the ORM/SEGR, in that when using the SEGR the FCV stays completely open until shutdown and the egr stays completely shut all the time.
Author:  richardkf [ Thu Oct 18, 2007 8:20 am ]
Post subject: 
tim wulf wrote:
Change the air filter. That's easy. Check the FCV by shutting off the jeep and running around to the front of the car and putting your ear close to the hood. within 5 seconds you should here the FCV open back up. It should be a crisp clicking sound if it's clean. If its not working at all you won't hear it and that explains your rough shutdown.

The FCV is open all the time and closes when you shut the engine off. It sprigs back open in about 5 seconds.


I do routinely hear the FCV open after about 5 seconds after shutting down. I haven't listened out for it lately though. I will check that again tonight.

I changed the air filter and that has significantly reduced the hesitation issues. The hesitation is now barely noticable. I am going to change the fuel filter this weekend and I am pretty sure that it will eliminate the rest of the hesitation. By telephone, the dealership also told me to do these things before he takes a look at it to save me a trip.

The rough shut down has gotten better, but not as smooth as it used to be. I wonder if maybe the FCV is dirty and needs to be cleaned. Anyone know if there are any instructions on this site for that too? Is it a big job? I can prob get the dealer to 'trash' the one I have now (on paper) and justify a new one under warranty.
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