Racing idle while coasting down 20 ft driveway

[Rpm90001]

I have a strange annoying problem. I park on a driveway that has a slight incline. When I back out of the driveway I obviously coast backwards the 20 foot distance to the road. My problem my idle will race to about 4k for about 5 seconds then all is normal. Only races while moving/coasting down the driveway. No other driving issues...just backing out of the driveway. Very annoying. Any suggestions?

 

00 legacy l 2.5l 5 speed.

[Fairtax4me]

Does it do this if you coast forward out of the driveway?

 

Tried repeating this when the engine is warm?

 

Are you coasting clutch in shifter in R (so the lights are on), or clutch out shifter in N?

[Rpm90001]

Only seems to do it with backing down the driveway.

Fine when engine is warm, only on first start.

Backing clutch in and shifter in N.

Driveway is only 20 foot...short backing distance.

[Fairtax4me]

Strange for sure.

I know the ECU will sometimes hold idle up a bit when coasting if you push the clutch in with trans in gear. But that should be only ~1500 - 2500 rpm.

 

Try cleaning the IAC. The ECU may be bringing idle up some but a sticky IAC may be jumping to a larger opening than it's supposed to.

 

Could also be a problem with the neutral position switch on the trans. If it gets stuck closed it tells the ECU the trans is in gear when it really isn't.

 

Occasionally my car will hold engine speed up around 2000 rpm when coasting to a stop with clutch out, trans out of gear. When the speed gets to near 0 engine speed drops to normal idle. Never have figured out exactly why.