I have an '01 CL-S and for the last couple months my RPM's will drop at idle to about 450-500 and stay there until I actually hit the gas. Sometimes after a hard run the idle will drop to almost 250 and then pick back up. I tried putting the A/C on to see if it would raise the idle and it didn't. Also, I am not throwing a code so I doubt it's the TPS. I have checked the voltage of the battery with the car not running (12.8 volts) and the car idling (14.5 volts) and it's perfect. I cannot figure out what this is. Any help would be appreciated.

Josh
Excelerate LLC

 

Dirty IAC valve. It's on the side of the TB, run some some carb cleaner in it. Or take it off & use a Q-tip & some compressed air.

 

Yea, I've done this before, a few months ago. I didn't think it would get dirty that quick.

 

Fuel pump My was doing this, but only in cold weather. it's stopped since it's gotten warmer.

 

I think at 12.8v your battery is a little low. Should be 13.4v with motor off and a full charge. If you are still on your original battery, you've got to be due. Mine started cranking a little slower in the morning and I noticed a slightly rougher idle. I was also only getting 13.0 v at rest and decided to change it. What a difference it made. Mine was almost 5 yrs old and had 76k mostly fwy miles on it.

 

oh.........in that case

 

I had the same exact problem where if i just pushed the gas during idol the rpm would drop down and nearly stall below 800 rpm. I recently changed my filter on my intake and after that i never had that problem. So IMO change your filter? I had my old filter on for about 20k+ miles before i changed it.

 

The voltage is fine. I confirmed this with my Interstate rep. I really wish it was the battery b/c I figured I was due since the car is 4 years old and has 60k on it.

Josh
Excelerate LLC