Car engine shakes in drive but stopped

[debian0001]

My car shakes at red lights, I have to drop it in neutral to stop it... any ideas?

I replaced two motor mounts on it a while back and they both look good..... it's a 2002 Dodge Neon. kind of sucks

 

[jlee]

Is the idle any different? i.e. low / unstable idle while in drive, but if you shift into neutral the idle goes up to ~800rpm?

 

[Zenmervolt]

Pretty normal for small 4-cylinders to shake at idle with an automatic transmission in drive.

A slight drop in RPM is normal too. If there's a big drop in RPM though I'd look at the idle control solenoid. It may be either faulty and not compensating for the increased load on the engine when the transmission is in drive or it may need to be cleaned (if it's gummed up with junk it might not be able to open enough to compensate).

ZV

 

[phucheneh]

Wasn't there already a thread on this? Or was that some other dude with a Neon?

If it's just a steady vibration, it's probably not much to worry about. That motor/platform is not exactly the most refined combo. If the idle speed is correct, about all you can do it replace the mounts and hope for the best. You can visually check for a broken mount, but they're often not actually torn; the rubber is just weak and sagging. IMO if you replace one, might as well do them all.

 

[debian0001]

It's never done it before though, it's new.

I'll slow down, and it will start to vibrate and seems to not stop til I put it in neutral.

"Is the idle any different? i.e. low / unstable idle while in drive, but if you shift into neutral the idle goes up to ~800rpm?"

I'm not sure what you mean. If I'm at a red light with the brakes on and the car in drive, it will eventually start shaking, I then drop it in neutral and it's ok again.

I did check the motor mounts and they look ok.

Would weak spark plugs cause this? I don't recall when I did a tune up last...

 

[olds]

Idle speed is.....?

 

[Zenmervolt]

Would weak spark plugs cause this? I don't recall when I did a tune up last...

Spark plugs don't get "weak." If they're fouled you'll have a miss, but that's a lot more than just a bit of roughness and shifting into neutral wouldn't change it.

Check the idle control solenoid like I said earlier. It sounds like something's stopping the engine from being able to compensate for differing loads at idle.

ZV