Engine Vibration on an 01 grand am

I have an automatic 2001 Grand Am SE Coupe with just under 90k miles on it. I've noticed recently (since 85k) that whenever the car is idling in drive, it vibrates. This isn't normal engine vibration either, there's something going on and I can't figure it out. Here's what I've found so far:

- the car only vibrates when idling in drive, no other gear.

- vibrations disappear when the car is put into park or neutral

- the vibrations do not start until the car has reached its operating temperature, which is about 180-200 degrees

- the vibrations to not change when the air conditioning is turned on or off.

If anyone's experienced this kind of issue with their car or has any insight as to what might be causing it, I would greatly appreciate it. I've asked a pontiac technician of over 10 years over the phone and he's stumped.

Reply to
muldoonaz
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bad plug wires.

Reply to
=?x-user-defined?Q?=AB?= Paul

if it were the plug wires though, wouldn't it happen when the car was started? The vibrations only happen after the engine has reached about

180-200 degrees.
Reply to
muldoonaz

Are you sure your EGR valve is operating properly? I'm no expert, but maybe it didn't trip the Service Engine light or the bulb on the light itself is burnt out. Maybe you could have Auto Zone check and see if a code is showing up? The valve could be stuck open or the spring could have worn out. That's the only idea I can bring to the table...

Reply to
kairos

If the wire was totally shot, yes. However, plug wires (and most materials) resistance increases when hot and decreases when cold. Check them when they are hot. ~ 200-300F.

Reply to
=?x-user-defined?Q?=AB?= Paul

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