Vibration in Park and Netrual

[hitman17mk]

ok guys, i have a werid problem. my 2002 explorer seems like it has a rough idle. but only in park or in netrual. when in gear its fine. but out of gear the whole truck shakes. i tryed running some fuel injector cleaner with no help. any ideas?

 

[pcohenchicago]

If your RPM isn't going up and down (the sign of other problems) and if your idle isn't noticably low, then "most likely" the vibration is being caused by, what I like to call, "resonance". Your engine is idling at a certain RPM that is not resonating with the body properly and causing the vibrations. That's why, when you put it in gear, the resonance changes and thus the vibrations stop. This starts happening with cars as they losen up. I don't think it's an engine problem based on your description - just signs of age.

 

[hitman17mk]

anythign i can do about it?

 

[pcohenchicago]

Not really. It's a physical reaction between your engine's idle and the "loseness" of the vehicle over time. If you rev the engine slightly do you still get the roughness? This would prove/disprove the theory. If it only has the roughness when the idle settles into its' constant state but NOT when you rev it a tiny bit (if you can manage to do that), then it's the resonance thing and there is not much you can do other than having a tech tighten every bolt and piece of plastic in your vehicle.

 

[Buttsy]

Does the shake go away when RPMs are increased? Idle too low, broke motor mount, or EGR/vacuum prob are my guess.

 

[chriswells78]

...or a bad coil. That is exactly what my LS did when a coil went south.

 

[hitman17mk]

yes it goes away if i hit the gas slightly

 

[pcohenchicago]

Maybe have a tech check the things mentioned by other users here. If those are not the issue, and they can't find what it is, it's probably what I was discussing - which is VERY difficult to resolve, if it actually can be. I actually got this information from a lead engineer at Ford (a client of my company) so it's not a mythical thing, but it may not be something the line-level techs know much about. Even the engineer said that it can happen as vehicles age.

One thought would be to see if they can raise your idle a tad and see what happens? I don't know if they will do that, but worth asking about.

 

[hitman17mk]

but also it doesnt do it all the time. i'd say about 50% of the time :-/

 

[zedsdead]

hey bro you are having a rough idel problem, im not sure what the guy was talking about with that resonance thing anyways....check for a valve called the IAC, its an idle air control valve, they tend to go bad, its hard to pinpoint, but when you do it park and neutral is just idle air that the valve controls. its beside/ on the throttle body, you can pick up a chilton manual to see what it looks like, or just look up "iac cleaning" or "rough idle" on here, i just did it on mine and works great. use carbuerator cleaner and youll be fine, worse case scenario you replace the part, cant be too expensive.

z+