JHowell37

Not the typical boo-hooing about being 200-300 RPM too high. I took off the intake manifold, injectors, all the vacuum lines, throttle body, MAF (and the elbow it's mounted to.) I replaced every gasket, seal, and vacuum line. Put it all back together and turned on the car. It started out idling at 1500RPM. Eventually it crept up to 2200. I've pushed on the linkage and the throttle is closed at that speed. I've checked and retraced all of the vacuum lines. The mixture screw on the throttle body was turned all the way in. I hooked up the jumper wire and tried to adjust the idle as indicated in the book. It's really not changing anything. Any ideas?

JHowell37

I should add, it's an '85, 32-valve, auto.

SharkSkin

Block off the ISV and see how it responds. Make sure you've hooked that up correctly. Make sure you've tightened all of the clamps on the intake. Note that there is no mixture screw on the throttle body, but there may be an idle speed screw. Does backing it out change anything?

JHowell37

How do I block off the ISV? Can I just unplug the electrical leads on it? All of the clamps on the intake are tight for probably the first time in a decade. Actually, every clamp on the top of the engine is tight for the first time in that long. The service manual refers to adjustments made on the idle speed screw as either making it rich or leaning it out, which is why I referred to it as a mixture screw. Initially it was set all the way in (full rich as stated in the manual) and I backed it out several turns and it didn't seem to change much at all.

Mark

Make sure the MAF is fully seated. Hard to see!

Normy

What Mark says-

I just did the same thing to my '85 S2. I've had a problem with the idle too- but I know where the problem is. Apparently, the throttle plate does not always want to come to the fully closed position, resulting in a high idle. I have the idle bypass screw turned down to keep the idle around 1100 rpm on average...so occasionally I'm faced with a stalled engine when the plate does manage to close!

How to test if this is happening to your car: Start the engine, and when it is warmed up and idling high, reach down and pull upward [toward the seat] gently on the throttle pedal. If your idle drops, then you are in the same boat as me. I suspect that my super-cleaning of the throttle body when I had it out caused this. I'm still trying to figure out how to remedy this without taking the whole mess apart again. I suspect that strategic oiling and adjusting the throttle cable will work in the end.

Best of luck-

N!

RichS 1986928

I'm not going to be much help here, but I'm having a similar problem.

I tried the carb-cleaner in the ISV with no luck. She's idling around 1K right now. When I jumper
the two pins on the test point the idle goes up to about 1.5K.

The vacum lines were 'mostly' replaced but not completely. Boots are new, new injector seals.
The idle screw is tightened all the way clockwise. I'm guessing vacum leak. It's not the linkage.

Can anyone recommend the best way to start troubleshooting a vacum leak.. Like what
kind of tester should I get? I've never delt with vacum problems before.

thanks,
Rich
86.0

lorenolson888

Check the cable where it goes through the firewall..

after disturbing the intakes etc. the housing can catch and effectively hold th throttle open... the happened to my 86...

LO

SharkSkin

You can use a propane torch. Don't light it, just spray the propane gas around places where you might have an air leak while the engine is idling -- if the idle speed changes, you've found your leak. Do this in a well-ventilated area!

Mike Frye

<HIJACK>

Normy,

If you can get it to idle back down by pulling the pedal up, isn't there a spring or something on the pedal that needs to be replaced/adjusted?

I'm really glad you posted your reply though because I have a high idle (just 200-300, boo-hoo sorry JH, it used to be 500 before I found a few vacuum leaks)

I had mine on stands yesterday and for the first time it was idling fine, (was working on something else) when it went back on the ground it was idling high again, I couldn't figure it out but thought it might have something to do with the angle of the car which was supposed to be level but probably wasn't quite. I'll try your pedal suggestion to see if that does it.

<END HIJACK>

JHowell37

I should add on mine, as it gets warmer the idle speed increases.

Mike Frye

JHowell,

I think I see what you were originally getting at about the settings. I'm sure someone turned up the idle in response to some previous idle problem, probably caused by a vacuum leak or bad sensor. Idling it up made it seem like it was fixed. When you replaced all the vacuum lines you fixed the original problem.

You said you turned the idle down a few turns and it didn't seem to do anything. Maybe it's something that's so far out of whack you have to bring it most of the way back up before you start seeing any difference.

I'm new at this, but my money's on a vacuum leak or something still loose. I think if it were a bad sensor it wouldn't be increasing the idle as it warms, it would just be high all the time.

JHowell37

I was thinking the same thing in regard to the screw. I figured it developed another issue so someone just played with the idle until it sounded right again. It's getting to be time to dig back into it and try and pull some vacuum on the 7-way and see what happens. The only other thing I'm wondering is if the computer has to "re-learn" all of it's settings. I did have the battery disconnected for over a week.

JP Rodkey

Here is a very good start: http://www.nichols.nu/tip367.htm

Mike Frye

JH,

I don't know about the 're-learn' thing. I don't think it's like a newer car that has to have so many good starts and miles on it before it will give good readings on the OBD-2 and stabilize the idle and stuff.

I've had my battery disconnected a few times since I got mine home for various reasons and it hasn't made a difference (I don't think). I also don't remember seeing anything about this in the manual and I've read several procedures that deal with disconnecting the battery.

Normy,

It turns out my high idle wasn't affected by adjusting the pedal. But thanks. Today it started and idled fine at 750 until I hit the gas the first time, then it went up and came down to settle at about 1K? I still have some work to do...