MPH shoots at idle?

[DIYPTGUY]

Immediately after i started my car today the MPH gauge went almost up to 100 mph and the engine revved much more than normal, then then the needle went back down. It also did this when I put the car in park to fill up on gas, but not to the extent it had earlier. No codes came up when I did the key-ignition test(on-off-on-off-on). Any ideas as to what may be the culprit here? Disconnect battery maybe?

[CREWZIN]

Might be the IAC (Idle Air Controller). You can take it off and clean it.

[DIYPTGUY]

Thanks Crewzin! How would I go about cleaning it? Just water and rag? or just rag?

[CREWZIN]

Haven't done it myself but when I searched for others with erratic idle problems and a couple came back after cleaning it and said it was the source of their problem, I now suggest it to anyone with the same symptoms. I think you'll see what to do when you take it off. Don't think you can hurt it and one of the owners said it was full of dirt and that's what the problem was.

[quicksilverdon]

Originally Posted by DIYPTGUY

Thanks Crewzin! How would I go about cleaning it? Just water and rag? or just rag?

Almost any auto section has spray carburetor cleaner - I'd use that. (be careful, it eats paint).

But if I read your post right, you're not moving and speedometer jumped up??
(or are you talking about tachometer?)

[DIYPTGUY]

Hey, sorry I know its been a while since this thread was used. Crewzin, I cleaned the IAC with parts cleaner and the speedometer still shoots at idle. This only happens on certain occasions though. Maybe 1 out of 8 starts, and sometimes after I put it in park after driving it and it is simply idling.

Quicksilverdon, you are right. I am not moving and the speedometer needle moves like crazy.

Im no expert, but could a throttle body cleaning help matters? Thats why I had that recent post about seafoaming through the brake booster. Cleans out all the carbon supposively. Also, just shooting in the dark here, could it be computer related? Maybe a flash is needed?

Sorry If I seem to be constantly complaining about my "issues" lately lol. Its just that Ive let some problems go for a while, and want to get them fixed once and for all.

Thanks guys,

George