MBenzman

I have an 06 IS 250 AWD. For the past couple days with a cold start up the engine idles at 1800 RPM's. After some warm up, the engine will idle around 1100 RPM's. After about 5 minutes it will idle around 800 RPM's. The temp in my garage this morning was 55 degrees. The temp when starting up this afternoon was 33 degrees. Does anyone know what could be causing this? Thank you for your help.

The Chad

My S2000 does this during every "cold" startup (i.e., if it hasn't been run in awhile, it's weird being able to let off of the clutch, not apply throttle, and still move). I'd imagine this is pretty common.

Gtidan

It's nothing more than what a choke would do on older cars. It idles higher to allow the car to warm up faster. A very normal condition.......

PNice972

iTrader: (6)

excellent, i noticed my car did this also. thanks for clearing it up

lexi06

Mine does the same thing, I've had the car for 1.5 months now. A lot
of cars behave this way to warm up in cold weather. If it idles high after
warming up then it's something to look into.

Bichon

No, it's what the fast idle cam did on older cars. The fast idle cam raised the idle speed by holding the throttle partially open.

The choke did something different: it cut off part of the air supply on a carburated car, causing a richer mixture. On a car with fuel injection, the computer acheives the same effect by injecting a richer mixture while the car is cold. (Since a fuel injector does a much better job atomizing the fuel that a carb did, it doesn't need as rich a cold start mixture)

Gtidan

I stand corrected on the matter. Thanks.

lobuxracer

iTrader: (2)

Bichon - sounds like you might have set fast idle and choke on a few carbs. So have I. Everything you said is dead on with one slight thing - A sidedraft Dell Orto at WOT atomizes fuel better than any injector. Injectors are great and all, but the BSFC numbers out of those carburetors at WOT were legendary. I do wonder about the new crop of GDI injectors though. I haven't seen any tests directly comparing their performance to the best carburetors. Unfortunately, that's the only thing about carburetors that's better than EFI. EFI does everything else so much better it isn't even funny.

PharmISee

At what RPM do you guys reach to warm up your car? I usually wait till 1K rpms and then start to drive. Is warming up your car actually good for your engine?

muffin57

cool. mine does the same. i was going to start a thread myself.

Technique

The topic of this thread reminds me of Banzai! hehe... "A very high idle speed betting game!"

VikH

iTrader: (5)

Mine idles at exactly 1k RPMs when cold. Noticed this when letting off the brake and the car lurches forward.

Bichon

How did you guess? Back in the late '70s, I helped a few high school buddies keep their rusty old clunkers (a Nova, a Vega, even a Rambler with a three speed column shifter!) on the road.

It was fun, but I'm sure glad that today's vehicles have fuel injection. Starting a car in sub-zero weather used to be an art -- now it's a no-brainer.

Lexmex

Weather and air temp can do it for you. Sometimes when I start up my RX after work, it starts and has extremely low idle...then I noticed the outside air temperature is in the 80s. When it is cool, my idle can go up high and then bottom out at a normal 750.

SASK250

I haven't really paid attention to the RPM's, but it does idle higher initially when it's cold then seems to slow down. Sometimes, it seems to go up and down. The morning temps the past 2 weeks have been between +5 C and -9 C.