Rough Idle

[ChiefRudy]

Every now and then when I'm in gear sitting in traffic the Idle will give a ruff little shake for 3 seconds and then it will go away. Then 30 seconds to a minute later it comes back for 3 seconds and then goes away again. I only notice it because the shake goes through the seat into my back. I don't think it's trying to stall though because I watch the tachometer when it shakes and it doesn't move. It doesn't happen all the time though and weather doesn't affect it because it has happen in both warm and cold weather.

Does any one else have this happen?

Is there something I can do to fix it or is a something more involved that needs to be done at a dealership or something.


Thanks

 

[Atrus]

I get that, although I don't think it's bad at all. All of my previous cars have done this to some degree at idle.

Not sure if it's still done this way (I think it is), but it used to be that at idle the PCM would slightly run the engine lean, then rich, lean, rich...it'd just put it over the line and then switch the fueling to even it out.

My Prix really was noticeable when I put in polyurethane engine mounts. Felt like a school bus at idle.

 

[JeepJeepster]

Not noticed it much with mine. May not be a bad idea to run a good can of cleaner through the fuel system. I use Valvoline Complete fuel cleaner.

You should stop at a redlight in an old ZJ with the I-6.

 

[Atrus]

just under 9k on my '07 and I see it do this - I can actually see the passenger seat shake slightly. Like I said, all of my vehicles have done this, so I've never questioned it.

 

[Marlon_JB2]

You call that rough? Hop into a japanese 4 ****** front wheel drive from the '90s. You'll appreciate the Libby, lol.

 

[jeepgirl0385]

Mine does it too. I never thought too much of it. At least it's not the only one!

 

[Dave]

ChiefRudy....since yours is an 06 and you are in warranty (3/36) you could take it to the dealer and see what they say. It would be interesting. What Atrus is saying about the PCM makes sense.

Mine is not doing that.... Not yet anyway.....

Dave

 

[ChiefRudy]

I ran a cleaner a few weeks ago. At least I know it's not just my KJ doing it. I really only notice it when I got nothing else on my mind while I'm in traffic. I think I will ask the dealership about it. My Jeep has to go in for the blower pretty soon. Thanks for the info guys.

 

[Dave]

I ran a cleaner a few weeks ago. At least I know it's not just my KJ doing it. I really only notice it when I got nothing else on my mind while I'm in traffic. I think I will ask the dealership about it. My Jeep has to go in for the blower pretty soon. Thanks for the info guys.

Let us know what they say.......other than "can't duplicate the rough idle"

Maby it will be a simple adjustment????

Dave

 

[tjkj2002]

What Atrus is saying about the PCM makes sense.

Yep that is normal,all fuel injected vehicles do that,cycling between open/closed loop about every 1 second from the given voltage from the O2 sensors.

Maby it will be a simple adjustment????

There is no adjustments to make without remapping the fuel curve software in the PCM.Oh and the timing is the same way.



The biggest reason for the vibs at idle in gear is the fact that our engines are a 90 degree V-6,making it a little rougher then 72 degree V-6's.Also the more cylinders the smother the engine since the more cylinders firing cancels each other out.A V-12 will be much smoother then a V-6 anyday.Oh and OEM engines are not perfecty balanced to start with,the pistons,rods,and such are close in weight but not perfectly equal which creates vibs.Balancing engines is very labor intensive and costs some $$$$,but it sure does make on hell of a difference in smoothness,rev's quicker,and generally better reliability.

 

[ChiefRudy]

Yep that is normal,all fuel injected vehicles do that,cycling between open/closed loop about every 1 second from the given voltage from the O2 sensors.

There is no adjustments to make without remapping the fuel curve software in the PCM.Oh and the timing is the same way.



The biggest reason for the vibs at idle in gear is the fact that our engines are a 90 degree V-6,making it a little rougher then 72 degree V-6's.Also the more cylinders the smother the engine since the more cylinders firing cancels each other out.A V-12 will be much smoother then a V-6 anyday.Oh and OEM engines are not perfecty balanced to start with,the pistons,rods,and such are close in weight but not perfectly equal which creates vibs.Balancing engines is very labor intensive and costs some $$$$,but it sure does make on hell of a difference in smoothness,rev's quicker,and generally better reliability.

Too bad all of that work isn't covered under the warranty

 

[ChiefRudy]

Let us know what they say.......other than "can't duplicate the rough idle"

Maby it will be a simple adjustment????

Dave

If I remember to tell them I will. I say that because I forgot to tell them the lasttime my jeep was there. sad2.gif

 

[Bboyyumm]

"whew" I was scared for a sec there..

 

[ChiefRudy]

"whew" I was scared for a sec there..

I don't even notice the little shake anymore. I had my KJ less than year when I made this thread.

I can't remember the last time I noticed it.