my tach is dancing

[indy240]

My idle jumps from 500 to 1500 rpm. Anyone know what sensor causes this? I have a good idea what is causing it, but if anyone has had the problem and knows what sensor it is it would take the guess work out of it. Thanks

[fleaf]

mine did that too once, found out to be a leaky air intake valve. I replaced the whole thing, and now it idles perfectly fine.

[transient]

Check the FAQ, there's a lot of info on this.