I have a 2004 G35 Coupe (5spd AT) that idles really low and harsh. I have cleaned the throttle body, MAF sensor, did a ECU reset/relearn but still idles low (around 500 rpm or lower). There are no engine codes showing on the dash so I’m curious on to know what happened. Any suggestions?

 

What's the condition of your air filter? Pretty quick and easy to check that. Aside from that I'd imagine your AF ratio is too rich, although if the car hasn't thrown a code for that low of an idle that is a little strange.

 

Might check your idle air control valve. It's attached to the intake and is one of the main things controlling the idle speed. They get dirty and can partially clog up from our corn-infused fuel(amongst other things) and I've taken off and cleaned them on most every vehicle I own. Some are expensive if not "cleanable" to replace but I don't think the one on the g is.

 

There is no idle air control valve on these engines, it's an air-volume algorithm that needs to be recalibrated by the steps in the FSM.

@SEAL 14 check out section EC - Engine Controls, in the "basic service procedures" that starts on around page 30, look for "idle air volume learning" and do the pedal dance method it shows. You will need to use a stopwatch so the seconds counts are exact, alternately you can use the android app Nissan Datascan 2 and a bluetooth OBD2 adapter and simply push a button.

Make sure the vehicle is in the ready state by following all the prep steps in the FSM, they must ALL BE MET for it to actually work. If you try it with the engine not being up to temp it's going to really F you idle up and you will need to perform it again. If the idle isn't correct after doing it once then just do it again and see if there's an improvement, sometimes it takes 2-3 tries to get a steady idle.

If the idle still won't set then you have a mechanical or sensor issue.

https://www.nicoclub.com/archives/in...e-manuals.html