High Idle - Trans Hunting

[coolnesss]

My 98 LE, with 70k miles, which otherwise runs flawlessly, idles a couple of hundred rpm higher than it should since a mechanic took off and reinstalled the intake manifold to replace a coolant hose.

 

They have turned the idle adjustment screw all the way down, and the idle goes down for a few days it seems, and then, comes back up.

 

The idle now also varies a little - it was rock solid before, and now will waver a little bit.

 

I thought vacuum leak - and sprayed water all around the intake manifold while it was idling, without any change in idle speed, so I think its not a vacuum leak.

 

I also have noticed that the transmission seems to hunt a little in and out of overdrive on the road.

 

I saw a post earlier about someone's hunting transmission - which someone responded to with a remark about throttle position sensor - which made me think - perhaps I've got a funny one of those things - but - does the TPS affect the idle?

 

And, it seems the car lacks power on hills at speed - not by much, but it feels like there is a difference.

 

The car lives in Acapulco, at my house there, so I don't have access to AutoZone's code readers.

 

All this is shadowed by a leaking muffler pipe - where the flexible link is in the passenger side pipe. I don't think that would have any effect on what I'm talking about - but, you never know. I bought a new pipe and it will be installed shortly.

 

Any suggestions?

 

THANKS in advance.

[02silverpathy]

A leak that early in the exhaust could be a loss of backpressure and cost you some TQ....the TPS would only mess up how the vehcile accelerates. Pull the battery cable off for a couple hours to reset and drive normal to get it back into swing...see if that helps. Another source of lost power could easily be the MAF sensor...take it off and GENTLY clean it with a teflon approved cleaner and a Q-tip (did I mention-GENTLY?).

[XPLORx4]

Adjusting the idle screw does NOT increase the idle speed, since the PCM will try to reset it back to the "proper" rpm! The mechanic who worked on your truck probably isn't familiar enough with the Nissan PCM. Your TPS is probably improperly adjusted, or you may have a problem with the IACV. It's more likely the TPS, since the tranny shifts incorrectly. Right-click and save as then navigate to page EC-75. Read pp EC-75 to EC-80, EC-121 to EC-126.

 

Right-click and save as, then navigate to page "AT-111"

 

That should help you out better.