I was wondering what causes cars to idle at different rpms when in neutral? Ive seen my rpm move from anwhere between 650 and 750 w/o messing with the A/C or anything else for that matter.

 

I guess thats how they got it to ULEV status. Most of us have raised our idle using consult, so that is stays a bit more steady.

 

Should i let my dealer increase my idle or can someone else do this too? I dont really like my dealership.

 

Idle can hover if you got a vacuum leak. (do you have mods)
it can hover if one of yoru sensors are off, or if something is not calibrated properly. It can ialso do this if you rplugs ar emessed up, or if you have a bad coil on one of the cylinders, or have bad compression, or even bad cats.

It definitly should not be bouncing up and down. it should be steady as can be. if yours is erratic, then you got a problem for sure.

Whyshould the dealer adjust your idle? if its not working proeperly its because you have a problem, fix the problem, dont work around it. You will most likely need to bringthis to the dealer, and if you dont trust a dealer, then who can you trust? joe mechanic?

 

My idle has been fairly erratic since the day I bought it. I figured it was "normal" but comparatively, my 1998 Infiniti I30's idle is as steady as a rock and it has 70,000 on the clock as opposed to 2,400 miles on my Z33.

I hope that it doesn't turn out to be something major-they shouldn't ship from the factory in this condition.

I'll probably take it to Performance when I get some time...

 

Of the 6 Z's other Z's that I have seen in person. 5 of them had an erratic idle. Moving from 50-100RPM just sitting there. I believe this is normal.

 

Yea, ive seen this problem from day one. The new oil after an oil change seems to help alot. Im also looking into that torque dampener as a solution.

 

Through our ecu research, we have experienced that the Z has a very lean idle miss and that is what causes the poping that many have. It most likely also contributes to the rough idle. We have fixed this on our test car by adding fuel at idle by altering the 02 signal.....
Jason
MRC Motorsports

 

I have noticed from day 1 that my idle is not smooth IF I HAVE THe AC OFF. If I turn the AC ON, the Car idles a few RPM higher AND it's Steady as a ROCK. once I turn the AC off again the idle is a few RPMs lower and it bounces 100 - 200 RPM.

I don't worry about it.

 

Switching to synthetic helps. Here's why: As j's350z stated, the idle on the Zs and most modern cars is set to very lean. Even the slightest amount of oil leaking past the valve guides or the rings will carbonize and mess up the combustion process. Synthentic oils don't "burn" in the traditional sense and therefore don't release any carbon so even if they leak, they don't interfere with the combustion cycle.

 

I've been running synthetic since my first oil change, idle never changed after switching.

 

i have done nothing to my car since the day i bought it, and the idle seems to be a tad erratic....so just another "normal" feature that i will just live with i guess

 

I told the dealer and they said it was because of the CAI. They adjusted something i forgot, still very minor rev increase. Normal.

 

The dealer will always try to blame things like that on an aftermarket part. Especially if they don't really know what's going on.

 

I just installed a earth grounding kit and it smoothed out my idle big time.