Idle Air Control Valve - High Idle (1 Viewer)

[w4oa]

Ok, tell me if I should mess with the IAC on my LX-450 or not. I have high idle when hot in park or neutral, anywhere from 1200 to 1800 rpm, in drive around 900-1100, both with a/c on. Tapping accelerator pedal may or may not make 100 rpm or so decrease. With a/c off, may or may not decrease whatever the high idle is. When cold, idle is normal, 600-700 with a/c off, 800-900 with a/c on. The throttle body has been cleaned twice in the past few days, once by me and once by a real mechanic.

Seems like the only thing left to check is the IAC valve, by taking it out, inspecting and cleaning it. However, I have been warned by my TLC guru not to mess with the IAC. I know it is only a stepper motor with a plunger, and the likely cause of the high idle is the plunger sticking when hot. Is the plunger plastic? What would cause it to stick?

So, what are my chances of removing, inspecting, testing and cleaning the IAC without breaking anything and making my 450
undrivable??? (I need it to go to the Dayton, OH Hamvention - ham radio convention next weekend.)

Mitch in Mobile, AL

 

[CJF]

Seems like the only thing left to check is the IAC valve,

Nope.

First of all, since tapping the pedal "may" bring down the idle, you need to get under the hood while this is occurring and see if you can bring it down by manually closing the throttle. If so, throttle cable is probably your sole problem.

Other suspects include throttle postition sensor and air flow meter (mass air sensor on later models).

Curtis

 

[w4oa]

Thanks Curtis... I'll try those suggestions.

Mitch

 

[smokethedog]

I got the exact same problem, if you fix this please post what the fix was.
thanks

 

[w4oa]

Well, Curtis is a GENIUS!!! The problem WAS the accelerator cable. It was just a smidgen tight. I could manually close the throttle and the idle was perfect ~600 - 650 rpm. I could manually open the throttle, let it go, and the idle would only go back to ~1000 - 1200. So, I sprayed the throttle cam (that the accelerator cable connects to) with anti-seize spray, and I loosened the accelerator cable outside nut a half-turn turn at a time (and snugged up the inside nut - throttle side) until the idle would drop back to ~600-650 when I released the throttle. FIXED!!!

Why do we always overlook the obvious??? And make a job much harder than it actually is??? Anyway, I won't tell you how much I spent on carb cleaner and on the air intake hose (the big one) that I busted to spray the carb cleaner into the throttle body, nor what the mechanic charged me to clean the throttle body. All helped a little but the final fix was just to relieve the tension on the accelerator cable!!!

THANKS CURTIS!!!

Mitch in Mobile, AL

 

[Domek]

I have similar problem but the revs go up when the A/C is on. ones the A/C is turn off it goes down to 600-800rpm. Nothing happens if I tap On the gas pedal. I press down(tap) the pedal hoping the rpms would come down and the rpms go higher. The Mechanic told me I need to replace the Idle air control Valve. Which it's an expensive part to replace A while back I check w/ CruiserDan $331.00

What are the simptoms when this valve don't work?