SlimBoJones

Okay, I've looked at a few threads regarding problems with these particular things.

The reason is, my car's idle oscillates between 500-3000 RPM when it's cold. Kind of like if you pull out a vacuum line from your throttle body and it goes crazy.

When it's warm, it stops oscillating, and remains at a steady idle, but idles rather high - around 1000RPM on the stock tach. The weird thing is, my idle speed set screw is ALL THE WAY IN, and it still idles fast. I can't turn down my idle speed any more.

I removed my Fast Idle Valve, and cleaned it thoroughly and inspected it. Visually it looked quite good and clean, but you can't tell a whole lot just by looking. I pushed on the plunger a little to make sure it travelled okay.

I also checked for air bubbles in my coolant, and found none. A nice solid stream of coolant shoots out of the bleed valve. The idle problems happen everytime I start up, they are not sporadic.

I replaced my PCV Valve, and checked for leaks on the vacuum line going to it, and around the PCV Valve seal itself. It all looked good. I noticed a lot of gunky buildup under where the PCV valve plugs into the manifold though.

I visually inspected the vacuum lines, and they looked to be in good shape, and I don't hear any hissing. I detached each line one at a time, and plugged the fitting with my finger to see if I could isolate a "bad vacuum line". None of the lines seemed to be causing any problems.

I'm a little confused because:

a) The oscillating idle only happens when cold, which suggests the FIV is phooked

but

b) since my idle set screw is all the way in, and I STILL have a high idle when warm, does this mean I have a lingering vacuum leak elsewhere?

Has anyone here ever had to replace a FIV? Have these things ever been known to stay stuck open, even when warm? Would something like that cause what I'm seeing with my car?

Any input you can offer would be SUPER appreciated...

Thanks!

-SlimBoJones...

imported_JookSingKid

stop playing with the fast idle screw.

Check the timing on your motor.
has it been advanced? has it been retarded?

Check the throttle cable for slack.
Check to see that you don't have sticky throttle body, that its fully returning to the close position.
Check the TPS sensor - I can be adjust that back and forth like a dizzy. you can use that to slighty adjust your idle.

bbarbulo

iTrader: (2)

the JSK said it all... I would start with letting the t-cable get some slack in it. Then I'd get a known good FIV and try it out. Lastly hook up a gauge to see if you have vacuum leaks listening for vacuum leaks is an exercise in futility.

funny thing is, when you get the settings right, your car should stall cuz you fucked with the idle screw

imported_Cablerat

The fast idle valve is pretty much everything that controls your idle when car is cold, cuz it's coolant temperature controlled.. It may look line it's fine but it may not be.. I'd say replace that.. I have 3 cars with that prob and for all of them it was the FIV!

imported_Cablerat

TPS sensor should rise up steadily to 0.5 V I think..

SlimBoJones

Thanks guys I'll check all those things tonight.

Very much appreciated...

and yeah... now that I turned my idle screw all the way in, I'm basically hoping I can fix one of these things to make it stall =)... ha.

SlimBoJones

TPS should read 0V at fully closed I take it?

bbarbulo

iTrader: (2)

TPS is tested by resistance, not voltage (disconnect and turn by hand as an assistant reads the resistance)

imported_Cablerat

heheh where's my coffee?!?

bbarbulo

iTrader: (2)

Timmy's got it

SlimBoJones

*lol*... how many ohms at fully closed for the TPS? =)