2003 neon SXT, idles great in park. When placed into gear the RPM'S slowly drop until the car starts to shake . Not a lot of shaking but you can tell its not right. It goes from about 750-800 down to about 500 to 600 RPM. Is there a part that controls this? I don't want it to get worse and start to stall out by going any lower. Please I need your help!! thanks

 

Engines always idle lower in gear because there is strain from the transmission being engaged. Normal. How slow are we talking about though? Shouldn't be more than a couple of seconds...

 

What is the idle RPM? Are there any check engine codes?

 

No codes or engine light. If you watch the gauge you can see the rpm's slowly go down. like I said it only goes down enough to make the car feel rough and lightly shake. Seems that if it were to go any lower than it is the car would probably stall out. I do not want that to happen as it is my daughters car and she is a new driver. she would definitely panic if it stalled in traffic.I know the idle drops when in gear but it should not cause car to shake. When it is in park it is so smooth you don't even know the car is running.

 

Mine shakes. Usually a sign of a worn/broken engine mount and or torque struts, especially on higher mileage cars, and I'm pretty positive mine is toast.

 

I think most of the people on this site, or that own a 2nd gen neon have this problem. when I had mine it did it since it was brand new (4 miles) and the dealer told me that was normal. although you can never trust the dealer really. I would go with what Darthroush said about the motor mounts and /or the torque struts.

 

Ok, I got a new toy today (Actron CP9180) and sit in my neon and played with the live read function after clearing a code about the evap system leak. My neon sits and idles at 733 RPM with no AC on. darthroush has a point however. a bad motor mount can cause excessive shaking while in idle.
BTW Advance auto has the scanner 50% off so I got it for under 100 dollars and free shipping! (sorry for the spam I think some eof the regulars would like to know this)