I have about 800 miles on my 2006 manual V6 and I noticed the last few times I drove it that the RPM's will not go down to 0 unless the car is turned off. When I turn the car on and have it in nuetral, first gear, or reverse, and do not touch the gas at all, the rpm is around 500 to 1000rpms. I'm no car expert but this doesn't seem normal and was wondering if anyone else has experiencd this or if anyone knows what could be the problem. Or maybe it is nothing to worry about? Also, sometimes when in nuetral at a stop light the rpm needle dances a little from 750 to 1000 rpms without me touching anything. Should I take this in to get looked at? thanks

 

Got any aftermarket mods or tunes on it?

TC

 

What you are seing is the idle RPM that is normal for any car, it will only read zero if the engine is not running at all. First car with a tach? The 250 rpm variation at idle in nuetral is a little odd though.

 

Should idle at about 800 rpm.
Fluctuation is odd.
RPM's should stay steady at idle.
Is your A/C or defrost on?
If the compressor is kicking on and off the rpm's may change slighlty.
250 seems a bit much to me.

 

edit: nevermind

 

I'm thinking the same thing. I'm willing to bet it's the A/C that is causing the fluctuation.

 

Have you ever had a car with a tach before?

 

Oh, I know this! It's a wide-spread issue with all car manufacturers, I believe it's called "the engine is running". It's caused by the air/fuel mixture firing in the cylinders, thereby pushing on the pistons and causing a rotational speed at the shaft of between 500 and 1000 rpm. The worst is, it also makes the engine burn your fuel!
We've all been waiting for a TSB on this for the past 150 years. Sorry.




Sorry, but I just couldn't resist!

 

No aftermarket mods.

I have driven a truck with a tach. It was my dad's gmc sonoma. I never noticed where it idled at but that was a few years back when I didn't really pay attention.

Yes, the air conditioning is pretty much always running. I've only noticed the needle jumping 1 or 2 times.

Thanks for the feedback on this. It will make me more at ease now when I see those RPM's at 1000.

 

 

 

That was a good read.

If you look in your owners manual it will tell what the idle RPM is for your car. 750-800 is normal for most stock cars.

 

most cars idle at 800RPM without an AC and 900-1000 with an AC (especially smaller engine ones)
RPM going down to 0 while running is only possible if your engine stalls, your engine should always be revving while idle.

as for the fluctuation, if you rev it up then let it go, and the RPM goes down below 500RPM then goes back up.. this usually indicates a problem with one of your engine sensors
MAF, MAP or NE Sensor.

however if the needle just goes up and down between 500 and 1000RPM, then you probably have a strange issue on your hand, do you feel the engine RPM fluctuating too, or is it just the tach?
could be a tach cable problem

 

Yeah..I have a problem with the revs, too. Same thing. Dang RPMs just keep going until I turn off the ignition.

Works for me!