Oscillating RPM when on Park and Neutral

[tiuse]

Recently I noticed the RPM meter moving up and down as if I was steping on the accelerator and releasing it when on the Park and Neutral gears. I also noticed that the car will move at 20 miles an hour without me steping on the gas. Lastly when trying to stop the car I noticed that the car downshifts the gear when I am close to coming to a complete standstill.

I took the car to the dealer and this was their response. After running their diagnostics computer code that came up is P505 dealing with the Idile Control Valve.I had ICV changed and the problem was not solved. The dealer then said they have to do the following:

Vehicle needs Idle Air Control motor($395) andpossible on-board computer($1035). Upper intakemanifold is leaking and must be replaced($965).Engine air flow meter is defective($225). After newparts are installed, a vehicle software update must beperformed($99). All prices before tax.We believe the transmission may have an internalproblem but this cannot be determined at this pointdue to road conditions. Additionally, anytransmission diagnosis can only be performed afterengine repairs are complete. All engine repairs mustbe done in order to ensure that engine is runningcorrectly.

IF anybody has any insight on this problem let me know.

THANKS

[AZhitman]

After running their diagnostics computer code that came up is P505 dealing with the Idile Control Valve.I had ICV changed and the problem was not solved. The dealer then said they have to do the following:

Vehicle needs Idle Air Control motor($395) andpossible on-board computer($1035). Upper intakemanifold is leaking and must be replaced($965).Engine air flow meter is defective($225). After newparts are installed, a vehicle software update must beperformed($99).

Time to fire your dealer.

They replaced your IACV, after telling you that was the problem, and it didn't solve the problem.

Tell them you want your old IACV back then.

Looks like they're stabbing in the dark. An ECU can be found for much less than that, and a "leaking intake manuifold" is re-sealed, not replaced (idiots).

If the MAF was defective, why didn't they tell you that in the first place? I may have a new OEM MAF I'd sell for cheaper...

Software update? They mean resetting the ECU?

Which dealer is this? I'd like to see their Service Advisor come on here and defend his vague and erroneous assessment.

[maxhopper]

I agree with Greg (AZHitman), you have an intake made of composite material. Is the intake cracked, or are the gaskets leaking? If it is the intake, you can surely find one in good condition from a junk yard in your area (try http://www.car-parts.com). If it is the gaskets, you could do this yourself.

Check our sponsor's prices (Midway Nissan or Pinnacle Nissan)for the other parts you need (IAC motor and MAF), and I'm sure the members here will give you great advise, should you have any questions about installing these parts.

Try reflashing your current ECU before buying another one. See if you can negotiate the reflash price to .5 hours from the dealer.

Doing the labor yourself, and getting the parts below what the dealer would charge you, equals up to some big savings!

[Duane Womer]

Hi new to Group Iam having the same problem and i know myIAC was bad because it failed when i ohm checked the valve itself it came in for ahigh idle now after replacing the iac theidle searches .ohm checked harness from iac to ecm but when i ohm test the maf and other sensors in that circuit i get a n ohm reading of.776. After process of elimation of one sensor at atime resitance still there untill ecm and tcm unpluged.Help

[maxhopper]

Welcome to NICO!

Here is the diagnostic procedure for the IAC valve. Click the pictures to change sizes.