help..my idle went crazy

[SNStang50]

hey guys, long time no talk...anyway...yesterday i ran out for work, and when i was coming back to the office, all the sudden my idle jumped up to around 2K and it won't go back to normal....i have no idea what could've caused it to do that out of the blue but it's getting on my nerves and i'm sure it's sucking down fuel doing that......it's not throwing any codes or a check engine light and i checked the throttle cable to make sure it's not stuck or anything, the throttle body is closing like it should....any ideas? any help is greatly appreciated...thanks!!!

 

[chuck943]

unplug IAC and see if it comes back down or better yet tap it with hammer and see if maybe it's just sticking

 

[SNStang50]

just tried it.....didn't do anything....i unhooked it and tapped it w/ a hammer.....nothing.....

 

[chuck943]

If you unhooked IAC and idle stayed at 2k it is a binding cable or throttle body. You elliminated the PCM commanding it when you unhooked the IAC.

 

[SNStang50]

right...and i checked the throttle by hand to make sure it was closing, so it's not the cable.....so it's gotta be the throttle body......fantastic...

 

[chuck943]

unless maybe you have a vacuum leak,thats still a possiblity.
would have to big a big one like PCV or brake booster line.
Did u unhook cable from throttle body to see if it would go down?

 

[SNStang50]

yeah, there's actually a little bit of play in the cable so that couldn't be keeping it open

 

[chuck943]

make sure you don't have a vacuum leak before jumping on throttle body,u should be able to hear it.
it would have to be a big one,could also intake manifold gasket blown out. take some oil in squirt can or wd40 and spray it around sides of intake and at the bigger vacuum lines and see if that effects the idle or you hear it sucking.

 

[SNStang50]

yeah, that makes sense to check that first......i doubt it's the intake manifold gasket...i'd figure it'd run like crap if that went....other then the idle it's running perfectly normal

 

[final5-0]

V leak
isc dirty
meter dirty

Grady

 

[Stanger007]

Sounds like a vacuum leak to me if it happened all of a sudden. It'll be a large one to jump that high -- you'll hear it.

Areas to look at are on the driver's side vacuum tree, brake booster line/valve and PCV (behind intake).

Wes

 

[95gtdude]

mine did that too and it was the pcv line broken were it "T's" at the manifoild.

 

[WHITE94COBRA]

I would still think it's the IAC, when mine went bad even when I disconnected it, it still idled high. My money is there.

 

[SNStang50]

hmm....well at this point i'm hoping it's a vacuum line off of the pcv b/c that'd be the cheapest solution.....that would make sense though seeing how it was running and idling fine and then just out of nowhere it started doing that....i'd think if it was the iac that i'd have a check engine, b/c when i unhooked it it gave me a check engine light and didn't lower the rpms at all

 

[Blackened302]

keep us posted!

i'm going through the EXACT same thing, and have narrowed it down to something mechanical (i changed my idle w/ the tweecer, but even w/ it off the idle is still up there).

 

[chuck943]

hmm....well at this point i'm hoping it's a vacuum line off of the pcv b/c that'd be the cheapest solution.....that would make sense though seeing how it was running and idling fine and then just out of nowhere it started doing that....i'd think if it was the iac that i'd have a check engine, b/c when i unhooked it it gave me a check engine light and didn't lower the rpms at all

Thats why I suggested tapping it with a hammer. Usually if they stick just tapping it with a hammer will un-stick it for a while.

 

[Blackened302]

fwiw: fixed the problem--pcv valve was half-way out.

after i made sure it was completely in, my idle dropped to where i set it.