High idle

[nuclearpenguin]

I read alot of threads regarding this and can't seem to find anyone else with a problem quite like mine, so here it is:

I grounded the correct pins, set the BISS, ungrounded the pins, started the car. My idle was just how it was when setting the BISS. Cool, good, awesome. I backed out of the driveway, got a block away from the house, and my idle was at 1800rpms. This was about 24 hours ago, it's been around 2000rpms since then. There's no idle surge or stutter, or stalling, just a really high idle. I've looked all around the engine bay and can't seem to find any vacuum leaks.

I just finished replacing my head so I know all the gaskets from the H/G up are brand new and in good shape, I've replaced the whole BISS assembly and the TB shaft seals. Since I replaced the TB shaft seals, my throttle has been a little sticky to open when closed, but I don't know if that has any effect (I've had this problem since BEFORE I replaced the head, BTW).

Also, the "idle switch" (the little tap switch that the throttle cable plate taps right behind the TB when the pedal is all the way up) seems to be in kinda crappy shape, theres just a bare wire taped to it, although the throt cable plate seems to be tapping the switch ok so I think it's within adjustment (if they're adjustable). Also I notice no difference in the idle whether this wire is attached or not.

So what should I look at?

What all does that idle switch do? Also, when I ground the pins for setting the BISS, what all does that disable? I'm just trying to narrow down the possibilities here.

 

[yokotabrat]

The idle switch is an input to the ecu. It (among other sensors) tells the ecu when to start controlling the isc to control the idle. Basically it puts it into a closed loop operation.

Did the idle problem you are having start with the TB shaft seal replacement? You mention the throttle body is sticky and that the idle switch wire doesn't affect the idle. This to me sounds like the throttle plate isn't fully closing which is causing the idle switch not to be activated. Also, if the throttle plate isn't fully closing, there is a chance that air is bypassing the throttle plate and that is what is causing your high idle. The test for that would be to manually try to close the throttle plate when you are getting a high idle. Also a logger will tell you if it's closing fully by looking at the throttle position, assuming the idle switch did not move at all.

Also, there is an easy way to check if the idle switch is working if you don't have a logger. You just need a multimeter and measure resistance from ground to the connector on the idle switch. If the switch is working properly, it should be a few ohms within ground when the throttle plate is closed. If not, then either the plate isn't fully closing, the throttle body isn't grounded, or the idle switch was moved from its factory installed position.

Hope some of this helps.

 

[the_skin_eater]

I had this problem...The BISS thing didnt work for me though...I blocked off the EGR, and that greatly helped...Brought my idle down to about 1k from 2.5k...

Check for any leaks too. I know I had vacuum leaks cause so much stuff was unhooked when I pulled the engine. Also like stated check the TB.
Could be many things. Just start somewhere and check everything you can.

 

[nuclearpenguin]

My logger has always shown 10%~ at idle, should it be at zero? I just assumed there was a idle threshold there. I thought I was having this problem before doing the shaft seals but maybe not, that was a while ago. I'll try flipping the throttle plate over tonight and see if that helps the stickiness/idle.

Anything else I should check?

 

[blcknspo0ln]

your throttle is 10% open. Put a little slack in the cable by loosening the 2 10mm nuts behind the intake manifold. your throttle position shoudl always read ZERO if you're idling.

 

[yokotabrat]

your throttle is 10% open. Put a little slack in the cable by loosening the 2 10mm nuts behind the intake manifold. your throttle position shoudl always read ZERO if you're idling.

That's incorrect. On 1gs, it should always read 10% at idle on a logger. On an SAFC it will read 0%.

It wouldn't hurt to check the slack in the cable, however.

 

[blcknspo0ln]

ah, I stand corrected. Damn 1g's always messing me up.

 

[Dream On]

Sorry to jack the thread, but I have a question...I did a log of mine today, and my TPS was reading about ~13% at idle. Should I put more slack in my cable? I can't get my idle below about 1400 RPM.