LeeTheSlacker

okay. so.
wtf is that other clutch switch on the pedal for?

when the clutch is pressed in enough to trip the switch, the cars idle bounces around 1500.

when the clutch is out and the switch isnt tripped, the engine shakes and the idle slowly drops to around 1000.

and this doesnt make any sense to me. any one have any ideas?

the tps is adjusted perfect. The idle a/f screw does nothing. The idle screw is tightened all the way down, and unscrewing it any doesnt really do anything.
i'm assuming its a vacuum leak making it bounce but i cant find it. besides that the clutch switch thing changing the idle is completely confusing me.

LeeTheSlacker

its not the clutch in to start switch, its the other one.

any idea what it does or why it would affect the idle?

AbortRetryFail

Are you sure it's the switch and not actually from the clutch being pressed?

Mine did this when the TPS was out of adjustment. During cold-start high idle the TPS was still in the deceleration fuel cut range. Fuel cut only engages above 1500RPM so the idle goes up, hits that, fuel cuts and drops back down until it gets fuel again and keeps bouncing.

I've got no idea how the clutch switch itself affects that, but with my car the extra load from the transmission in neutral was enough to keep the high idle below 1500 RPM. See if it's the same with yours.

If you really want to be scientific about it you could try pressing the switch by itself (remove it from the pedal and just push the button.) and see what difference it makes.

Edit:
My car is an 86 and it does not use the clutch switch to prevent you from starting the car. It IS, however, used by the cruise control to kill the cruse when you press the clutch.

HAILERS

Yeah. Instead of pressing the clutch pedal, depress the switch with your hand and see if you get the same results.

LeeTheSlacker

ive pressed the switch with my hand and its just the switch that makes the change.

with it unplugged it acts like its not pushed in at all no matter what, and hte engine idles rough and shakes around 1000.

switch in, idle bounces above and below 1500.
switch out, idle gets rough and drops to 1000. motor shakes enough to shake the car.

LeeTheSlacker

i emptied a can of flammible brake cleaner into the engine bay.

didnt find oooone leak.

if i pulled a vac line off and spray the cleaner into it the idle jumped up like it should.

but even resorting to completely spray bombing every bit of vacuum line and flange on the engine in mass amounts didnt cause one jump in idle.

could the bac coolant lines being kinda shitty make it jump?

im out of ideas here.

AbortRetryFail

Have you tried adjusting the TPS yet?

LeeTheSlacker

yup.
i have adjusted right with a multimeter right now.

1 whateverohm resistance with the car off, and 1v at idle with the car running.

ive adjusted it randomyl all throughout the range. it will only change the idle from bouncing to steady at 2k.

TweakGames

iTrader: (3)

mine does this exact thing.... I was told to have my TPS set for when the car is at its warmest. My idle will go to 1,500 @ cold startup, bounce for the first 10 mins of driving and then will start to smooth out. Also it helps if I drive the car, warm it up, then turn it off and let it sit. THEN the next time I start it the idle is perfect.

Dont know exactly why, but I'm guessing the heat finally gets to the throttle body since the car isn't moving. I DID NOT KNOW this wasn't normal... I thought it was normal to have a hight idle at warm up for the first 10 mins and then bouncing for 10, and then good idle 10 after that. Also putting the clutch in will raise the idle, letting the clutch out will drop it ..... *WEIRD* I am very interested on the fix for this.

MY tps is set for .998 k ohms when its completly warm.

LeeTheSlacker

bnefore i adjusted the tps the cold start idle was right at 1k.

now it shoots the hell up to 3k.

comes down, bounces around 2k.

and then when it warms up it bounces at 1500.

this is with the clutch switch pressed.

without it the motor will shake enough to shake the car and drop to a little over 1000.