Simple, in D or any other forward or reverse gear you are putting a load on the engine by activating the transmission. N or p are neutral gears that put no load on the engine and that is why you can take your foot off the brake in either one. The question is what is the normal idle rpm of your vehicle? If it is out of range then it must be adjusted.
The normal idle RPM of Neon is 1000. It just went up to 1500 when I stop at the red light yesterday. It was 1500 rpm on both N and P. It's never been like this. I think something is wrong.
Check of change fluid and filter--if this doesn't help it may be time for a rebuild
Possibly a Clogged transmission filter. Change the fluid and filter.
transmission down shift after fuild change
Yes. Your best bet would be to find a donor car with an A/T. If not then, it may get very expensive. You will need a bell-housing, torque converter, transmission & mount, drive-shaft, and all the shift linkage. Of course you can go with a floor shift if you are not trying to keep it stock.
depends, what kind of trans is if, if its a 3speed then that's as far as it should go. Have the engine and trans computers checked for trouble codes. The 4 speed will not shift when the computer detects a problem and sets a code.
It's a transmission where the gears do not change themselves, but have to be changed with a gear shift and a clutch.
Make sure brake lights are working - shift interlock is common to this circuit
Check transmission fluid level Change transmission fluid and filter
Check transmission fluid level Perhaps change transmission fluid and filter
no shift or bad shifting,
The transmission doesnt have a modulator. Shift points and pressures are controlled by the PCM.
change your transmission fluid and transmission filter if the problem persists then your transmission is most likely no good.