I have a '99 Series One Discovery w/173K on it. Last week the truck started a high idle thing. I have read the other High Idle threads, but my situation seems unique. Bascially if you start it, it goes to a high idle, but you can kick it down right away. Then once you drive it up past about 1500rpm, it stays around 1000rpm when in gear, and around 1500rpm when in neutral. I can ALWAYS kick it down by jamming on the gas pedal, whether it's in gear or in neutral. However as soon as I get it up above 1500rpm, the same thing happens, every time. So I find myself having to kick it down about 15 times on the way to work.

Any ideas?

Thanks!

 

my question would be what have you done recently that may affect the idle , if nothing I would say its a iacv prob.

 

No, nothing at all. It just started doing in a couple weeks ago while I was driving home from work. My neighbor is a retired mechanic, who's always tinkering on his cars, and he believes it's the idle air control valve. He said I should remove it, clean it with carb cleaner and see what happens. Is that what you recommend, as well? Of course I don't know where the hell the iacv IS on my truck. OK. I just went out and looked under the hood - it's right on the (front of the truck) side of the tube that goes to the air cleaner, correct?

 

Yeah, take the IAC off, and spray the ever living **** out of it with carb or throttle body cleaner. The crap that will come out of it will be nasty and black and you may even see chunks for stuff come out. Use gloves, and make damn sure you do it in a well ventilated area (like the end of your driveway).

Reinstall, and see what that does.

Good luck!

 

yeah, what he said.

Clean the Throttle body while you are in there...

 

OK. I took it all apart, cleaned it as thoroughly as I could with carb cleaner, a toothbrush, and a rag. It was DIRTY and appeared to be quite clean when I was through. It seemed like it MAY have made a difference for a minute or two, but I may have even been imagining that (wishful thinking). Time to replace the iacv?

Thanks again guys.

P.S. It appears my gas milage is suffering, as well....possibly to the tune of 10% less.

 

All the previously mentioned suggestions are where I'd start. No doubt.

 

Are there any trouble codes?
In addition to cleaning the iacv, you can also give it the tap test. Get it to act up, then tap lightly on the iac and see if the idle drops.
I would also clean the throttle plate as suggested by others.
Also, make sure the throttle plate is closed all the way. I've seen them stick and cause trouble like you're describing.

 

This^

" I can ALWAYS kick it down by jamming on the gas pedal" - You mean you can fix it by quickly pushing and releasing the gas pedal?

I agree it sounds more like a sticky butterfly valve. When is the last time the throttle body was cleaned?

 

Had to be either sticking butterfly, gas pedal, throttle cable gaps, iacv

Check the rave manual for the correct throttle and cruise control gaps and adjust accordingly

if you have a scan tool monitor the throttle position and make sure it always goes back down to 0% when you release the pedal

you can also run the car with the intake tube removed to peep at the butterfly .

also, instead of kicking the pedal, try tapping the throttle body with a screw driver. Same effect? Probably either stuck butterfly or incorrect throttle cable gaps

coukdnt hurt to also check to make sure the throttle position sensor is good