Low Idle speed

bighause · **Posted:** Sun Jun 07, 2009 3:33 pm

My jeep started idling at about 400 rpm recently, I'm not getting a check engine light or any trouble codes. When coasting at a few MPH it will stay at the normal idle speed, but once I stop it drops to 400. If I rev it to 2000 rpm and let off the gas quickly it will die.

Any ideas what to check? I replaced the air filter and plugs in the last 6 months and other than the low idle, it runs fine.

Guest · **Posted:** Sun Jun 07, 2009 9:14 pm

Sounds like you need to go down a jet on the primaries, raise the float level, and adjust the idle speed screw

sorry :lol:

Despite lack of a CEL, have you done the key-on-off-on-off-on-off trick to pull codes? Some codes can be thrown without a CEL

bighause · **Posted:** Sun Jun 07, 2009 10:10 pm

That would do the trick on my carburated quad...

Yes, I tried cycling the key but I didn't get any trouble codes.

VoodooMann · **Posted:** Mon Jun 08, 2009 12:03 am

mine idles around 600-650, and It sounds beasty :twisted:

, but I don't have any problems with it dying/sputtering...

very strange.

Maximum Carnage · **Posted:** Mon Jun 08, 2009 12:13 pm

Mine has done the same thing. About a month ago as I was approaching the drive way I applied the brake to slow down and it just died. I started it back up and it was just giving me low idle then turned off. Started it up again gave it some gas and it was good to go.

tjkoen01 · **Posted:** Mon Jun 08, 2009 12:31 pm

your idle air control (IAC) may be dirty or malfunctioning. i've cleaned mine on several occasions after noticing unusual things at startup or while idling. taking the throttle body off will allow you to do a better job cleaning it.

lil black liberty · **Posted:** Mon Jun 08, 2009 1:40 pm

Mine since putting on the LTT Air intake and a K/N performance filter and a dual dump flowmaster 40 sets at about 500-650..

bighause · **Posted:** Mon Jun 08, 2009 9:26 pm

Is the IAC one of the 2 things bolted to the throttle body? I'll try cleaning it tomorrow and see what happens. What did you clean it with? Is it something you just wipe clean with a rag?

JeepinJarhead03 · **Posted:** Mon Jun 08, 2009 9:37 pm

if you're standing at the drivers fender looking across the engine at the side of the throttlebody, the throttle position sensor is ontop, the idle air control is on bottom, both mounted to the side of the throttle body that you're facing

i use electrical parts cleaner - has no residue

i'm sure someone else will chirp in with something else that works just as well

tjkoen01 · **Posted:** Mon Jun 08, 2009 9:40 pm

you can buy carb / throttle body cleaner at your favorite auto parts store...not sure if straight up carb cleaner is safe.

lil black liberty · **Posted:** Mon Jun 08, 2009 10:35 pm

Why not use the crap they use for computers.. for like the thermal grease..

bighause · **Posted:** Tue Jun 09, 2009 6:30 pm

I took the throttle body off last night and it was pretty dirty inside. I removed the throttle position sensor and IAC and it had a lot of balck buildup on it. Cleaned everything with a rag and some carb cleaner I had laying around and bolted it all back together.

Runs great now, thanks for the tip Jarhead!

JeepinJarhead03 · **Posted:** Tue Jun 09, 2009 6:33 pm

throw a pcv valve in it next time you're at a parts store, might help keep it cleaner in the future, maybe, I don't know

they get dirty, just one of those typical things

Low Idle speed

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