# Slight RPM drop during cold weather **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [September 18, 2013, 8:20pm UTC](https://community.cartalk.com/t/slight-rpm-drop-during-cold-weather/81392 "2013-09-18T20:20:20Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![xaml](https://avatars.discourse-cdn.com/v4/letter/x/2bfe46/32.png) [@xaml](https://community.cartalk.com/u/xaml)\ **Post date:** [September 18, 2013, 8:20pm UTC](https://community.cartalk.com/t/slight-rpm-drop-during-cold-weather/81392/1 "2013-09-18T20:20:20Z")
I have a 2000 Corolla CE with 51k miles (bought a couple of months ago). It ran perfectly during the hot weather (75-80F) and it idles around 650rpm-670rpm. These couple of weeks, there have been very cold weather (60-70F) and it idles mostly around 650rpm but can drop to 630-640rpm. Sometimes, it will suddenly drop to around 612rpm (there will be a very slight shudder) and pick back up to 630rpm. This is with all accessories turned off. If I turn on the windshield wiper, then everytime it activates, it drops to around 612rpm and picks back up quickly. This only happens during cold weather. I don’t think it’s the MAF sensor…any idea what it could be? ---
**Author:** ![Rod-Knox](https://avatars.discourse-cdn.com/v4/letter/r/a183cd/32.png) [@Rod-Knox](https://community.cartalk.com/u/Rod-Knox)\ **Post date:** [September 18, 2013, 10:02pm UTC](https://community.cartalk.com/t/slight-rpm-drop-during-cold-weather/81392/2 "2013-09-18T22:02:18Z")
Could the operation of the AC be the cause? ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [September 19, 2013, 6:24am UTC](https://community.cartalk.com/t/slight-rpm-drop-during-cold-weather/81392/3 "2013-09-19T06:24:20Z")
I would clean the IACV (idle air control valve) and pour a bottle of Chevron /w Techron injector cleaner in the gas tank. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [September 19, 2013, 7:49am UTC](https://community.cartalk.com/t/slight-rpm-drop-during-cold-weather/81392/4 "2013-09-19T07:49:37Z")
Dropping to 612 and shuddering and idle rpm involvement w/the windshield wiper means there is definitely something wrong. There are numerous things that could cause this. The suggestion above it is a good one. If it were my car though, the first thing I’d do is make sure all the routine maintenance is up to date and check for vacuum leaks.