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Thumping, Knocking, hard jerking

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Old 12-28-2006, 11:35 AM
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Default Thumping, Knocking, hard jerking

I'll post this is External Engine also to rule out possibilities...

Sitting Still In neutral or in gear. I Have a 6 Speed.

While Idle their is a thumping, knocking, Not smooth in the middle of revolutions. So if I was sitting still I would feel this thumping, knocking, hard jerking. Every I would say 5 to 10 seconds then the engine will feel fine 5 to 10, knocking, fine 5 to 10, knocking, fine.

I did some searching on here and found out that most people have their rpm's go up and down.

My RPM's dont move.

Also searching turned up sensors might be going out.

And the last thing I found with my search was possible motor mount.


What I am Asking is:

Is their any other possibilties?
And how to rule out the above listed in order to make a correct decision.

Also: Yea I could just take to car to the dealer and ask them to look it over but I like to consult With you guys first so I dont get the run around....
Old 12-28-2006, 11:52 AM
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People have their idle go up and down? I've never heard of that. I would consider your idle to be good if it stays at one RPM. Can't help on the rest.
Old 12-28-2006, 01:02 PM
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An easy way to check your motor mounts is to get your car in the air, grab your exhaust by the Y-pipe and wiggle it. It should be pretty darn stout. If not, then your motor mounts are probably shot. Mine were wasted at 60k miles. I swapped 'em to polys and a lot of rattles/vibrations/knockings were gone.
Old 12-28-2006, 02:56 PM
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Check your plugs and plug boots. It could just be missing every once in a while.
Old 12-28-2006, 02:58 PM
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Originally Posted by ArcticZ28
Check your plugs and plug boots. It could just be missing every once in a while.
If it was missing every once in a while would it be that consistant? I would expect it to be more random and less cyclical.

If you're checking the plugs as a possible cause, post up the type and what you have them gapped at.
Old 12-28-2006, 03:30 PM
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Thanks Guys ill get it up in the air and tug on the pipes and check my plug boots. Then we will see whats up.
Old 12-28-2006, 03:50 PM
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Originally Posted by Gauge
If it was missing every once in a while would it be that consistant? I would expect it to be more random and less cyclical.

If you're checking the plugs as a possible cause, post up the type and what you have them gapped at.
Well it's impossible to count the number of revolutions the engine makes in between missing. I doubt it's as cyclical as it sounds, and again, it's just a possibility that's very easy to check.
Old 12-28-2006, 08:16 PM
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Originally Posted by ArcticZ28
Well it's impossible to count the number of revolutions the engine makes in between missing. I doubt it's as cyclical as it sounds, and again, it's just a possibility that's very easy to check.
Makes good sense. I wasn't arguing, just hoping you could point out my misunderstanding.




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