Idle is high

[9dreizig]

Stock 86 w CIS,, starts fine, runs great. Problem is the idle is really high,, Can't seem to adjust it out..
If I push down slightly on the throttle plate it goes right down as long as I hold it.
Suggestions ? I tried setting the mixture richer but it doesn't seem to help.

[Ronnie's.930]

The most likely cause is a air leak after the throttle body. Do you still have the vacuum limiting valve (aka - deceleration valve) in place? When I experienced a high idle that would not adjust away it turned out to be a faulty decel valve which was letting air by at all times . . .

[9dreizig]

Thanks Ronnie, I'll check it out.. Makes sense since I just put the engine back in

[WERK I]

Originally Posted by 9dreizig

Stock 86 w CIS,, starts fine, runs great. Problem is the idle is really high,, Can't seem to adjust it out..
If I push down slightly on the throttle plate it goes right down as long as I hold it.
Suggestions ? I tried setting the mixture richer but it doesn't seem to help.

Since you just put the motor back in, why not check to see if there's any binding or slop in the throttle linkage? You mentioned that any kind of pressure on the butterfly, results in lower RPM's. Start with the simple things first, then go deeper.

[Ronnie's.930]

I bet Dave has it covered - I didn't pay enough attention to the "pressure on the throttle plate" part in the original post! I agree that this would indicate that the throttle plate is not closing enough.

[fredmeister]

It could be throttle linkage related. I had to replace the throttle belcrank bushes on my engine mounted belcrank bracket since they were completely worn and distorted. its hard to see with the engine back in the car, but this could be the source of your trouble.
Also it could be the auxilairy air valve is not closing all the way. if your stock CIS is all there, check out whether this valve is closing when its warm.

[9dreizig]

Quick update,, I don't think it's the linkage because the TB IS closing all the way,, I need to push it open to get the throttle to drop....
Air pump/ stuff has been removed from the CIS..
I'm going to chase down the vacuum leak idea in the next day or so.

[mark houghton]

Since nobody has asked yet, then I will. How's your AAR working? Not closing, perhaps? Is power getting to it, to heat things up and close it when warm?

Simple in-car test would be to pinch the hose at the AAR completely closed to stop any air from entering. RPM's would instantly drop IF the AAR was stuck open.

[Tt surgeon]

Mine does the opposite, after about an hr of driving the idle drops to a point where the car will stall.
Same issue?
TIA, sorry to hijack, but a related issue

[mark houghton]

Originally Posted by Tt surgeon

Mine does the opposite, after about an hr of driving the idle drops to a point where the car will stall.
Same issue?
TIA, sorry to hijack, but a related issue

In your case, maybe too rich? Reach back there with your allen wrench when she's in the stall mood and tweak that mixture screw ever so slightly counter-clockwise. If that doesn't change the idle, then tweak it the other way. Just keep track of where you started.

But before messing with the mix, first adjust the idle speed via the screw that's a b- -ch to get to, to get your idle up and stable.

[smurfbus]

A loong screw driver does the job for the throttle screw.

[Tt surgeon]

thanx will try, but when it's not that hot or less than an hr of driving doesn't do it at all and idles normally

[oilonly]

Originally Posted by Tt surgeon

thanx will try, but when it's not that hot or less than an hr of driving doesn't do it at all and idles normally

Tt next time it happens take a look and see if your fuel pump fuse (6th one in from windshield) or 2 fuel pump relays (closest to windshield) are hot.

[fredmeister]

Originally Posted by mark houghton

Since nobody has asked yet, then I will. How's your AAR working? Not closing, perhaps? Is power getting to it, to heat things up and close it when warm?

Simple in-car test would be to pinch the hose at the AAR completely closed to stop any air from entering. RPM's would instantly drop IF the AAR was stuck open.

I thought that was what I suggested a few posts previous.

I called it the auxialiary air valve.....some say tomato some say potato.....you know what I mean.

[mark houghton]

Originally Posted by fredmeister

I thought that was what I suggested a few posts previous.

I called it the auxialiary air valve.....some say tomato some say potato.....you know what I mean.

Oops...so you did! Sorry Fred. That will teach me to stop scanning and read what's already been said.
AAV vs. AAR. My thoughts: A valve is either on or off, whereas a regulator is infinite in it's position. I have no idea which is the correct term, but we're all talking the same thing so who cares?

[fredmeister]

Originally Posted by mark houghton

Oops...so you did! Sorry Fred. That will teach me to stop scanning and read what's already been said.
AAV vs. AAR. My thoughts: A valve is either on or off, whereas a regulator is infinite in it's position. I have no idea which is the correct term, but we're all talking the same thing so who cares?

You are right Mark, the correct term is regulator. Good explanation too. It must be my New York accent that is throwing everyone off, ha,ha.

As a side note, mine stopped closing down as it warmed up and I wound up with an extremely high idle (2000rpm) a while back so rather than pay $1200 for a new unit, I removed it. The car is a little harder to start in cold weather now and is cold blooded for 2-3 minutes until it warms up, but works fine without it otherwise.

Later,
Fred

[mark houghton]

Originally Posted by fredmeister

As a side note, mine stopped closing down as it warmed up and I wound up with an extremely high idle (2000rpm) a while back so rather than pay $1200 for a new unit, I removed it. The car is a little harder to start in cold weather now and is cold blooded for 2-3 minutes until it warms up, but works fine without it otherwise.Fred

Here's an idea that might work: With the AAR removed but the hoses still attached to the manifold and IC locations, install a pull-cable operated valve and run the cable up to the cockpit. Pull it open when she's cold to get the high idle, then close it down when warm. Crude but just maybe affective. Or, to your point, just live with it.

And yeah, I thought I detected a NY accent. Just so happens my best friend is from Brooklyn.

[Tt surgeon]

Originally Posted by oilonly

Tt next time it happens take a look and see if your fuel pump fuse (6th one in from windshield) or 2 fuel pump relays (closest to windshield) are hot.

Both hot
I'm gonna do some diagnostics that mark suggested, but sounds like one of the fuel pumps is out.
c

[oilonly]

Originally Posted by Tt surgeon

Both hot
c

Tt I had the same problem as you, after driving for a bit the car would not idle, had to keep my foot on the gas at all times, I actually learned how to heel toe because of this problem. My fuse was hot and one relay. I rewired my fuel pump fuse like this 930 Fuel Pump Fuse Overload - The Solution. Now that I have two fuses and the two red relays I could pinpoint what pump was not getting power or was faulty. Maybe this weekend you come by Captree or maybe Milleridge In and I will show you exactly how I delt with this problem. It was not AAR or AFR adjustment related but instead power getting to both fuel pumps properly. JMHO

[Tt surgeon]

Al, that sounds good, give me a call on my cell
c