00 Altima Idle RPM and Accessories

[stocker2000]

My engine RPM at idle seems to be dropping more than I recall when I turn accessories on. Normal idle when warm for me is around 750 RPM. If I turn on the rear defroster, my engine speed drops to 500 RPM for about 2-3 seconds before coming back up to around 600 RPM (it never gets back up to 750). Other accessories (i.e. headlights, HVAC fan) produce similar effects.

I know some drop in RPM is to be expected when an accessory is turned on, but it really seems more noticeable lately. What maintains engine RPM as electrical loads are added or removed from the alternator? More to the point, what should I inspect/replace (if anything) to correct this?

Any help is always appreciated.

[NISTECH]

the iac/iacv is what adjusts your idle for loads. chances are you might have some carbon build up in it. try performining an induction flush on your intake that may resolve it, if not you'll need to look at the iacv operation with a functional testing scan tool.

[stocker2000]

Thanks for the prompt response!!

What's an induction flush? Doesn't sound like a DIY job.

[NISTECH]

to do it properly it really isnt a DIY job, but what it is basically is cleaning off the inside of all the air passages in your intake manifold and idle air intake system. I used to use an air charged cylinder with cleaning chemicals in it and an injector nozzle at the end of a hose you place in the intake tube in front of the throttle plate. once you get it started you can pull the fuel pump fuse and the car will run on it till it runs empty. this stuff pretty much washes down the entire intake system. and saturates any carbon on the backs of the valves and in the chamber that ends up getting washed away with a can of additive you put in with a full tank of fuel.