I posted earlier about an erratic idle frequent stall in neutral question on my 245. Thanks all for the advice . I cleaned the Mass air flow sensor with the appropriate cleaner and also used throttle body cleaner to clean out the body without removing it from the car. Lastly I used seafoam both some in a new tank of gas and also shot some down the vacuum line while the car was running to clean out the intake . The car put out a lot of white smoke and then ran great all day yesterday . Idle was smooth and the car seemed fine.

Today I started it and realized the car will not come off of a fast idle . Also the car is very hard starting . I will leave it sit some and see what happens.

Would appreciate any advice people have . Is there a possibly i clogged the car by running all the gunk out of the exhaust ? Or maybe I have clogged something in the intake ? Thank you !

When I cleaned my throttle body, the idle increased to about 1400 RPM. I finally had to readjust my throttle body and sensor to lower the idle.You can search how to do that or read the Bentley Manual. Two weeks later my IAC went.
In my research, I've read, if the throttle is still high after replacing a IAC, check for vacuum leaks.
Good luck.
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Sandy '83 244 DL current, '90 240, '93 850 memories

Original poster:

I have removed the throttle body and cleaned and ensured that the throttle position switch clicks properly. Also examined the air bellow tube and ensured it was intact without holes.

I have also installed a used Bosch IAC from another vehicle and cleaned it out prior to installation.

The car still shows the same symptoms. Idle escalates once the engine is warm and it will not come back down.

Does anyone have suggestions to explore next?

Hi Dale,

I spotted your post awhile back and saw you get the same good advice that I would have tried to post. I will try to help, if I can?

It looks like you have done all the things to stop excess air from getting into the engine from the places we normally look.

If you have the throttle plate as closed as much as it can be, that throttle switch is clicking to tell the computer that you and the throttle plate want it to idle, then it was left up to the IAC to do that.

Now, since you still have the problem the computer must be getting told that the engine is at some other operating temperature.
The only other perimeter not met is the ECU knowing the RPM's. I would kiss that last one off. It is running because it is getting a signal.

The engine coolant temperature sensor is the most likely candidate. It controls two things the for the engine, mixture for coldness to start and mixture for economy. Its then up to the ECU to decide things based upon that.
Pulse width for the injectors with side input from the O2 sensor, and timing!

You see if the ECU thinks its over heating it will retard the timing in order to prevent detonation. 1983 may or may not have a knock sensor but in either case the ECU has a program.

A hot engine can be seen two ways, one as just heat but it can also be a lean mixture. Without or with a knock sensor, a O2 sensor is being the "boss," it has to decide to enrich the mixture or move the timing. Emissions protocol in the program will be to fire the spark After Top Dead Center which revs the engine more but it cools the combustion chamber temperatures due to a less complete combustion. The protocol is an "idle emissions" situation.

If this is going on then it just might be the cause of your hard starting problems due to the ECS sending a low resistance signal or an erratic one for lean mixtures!
This is an 1983 and it could be old or its WIRING issues starting, I thought in 1984? '83? First year of the LH's, with the turn over from K-Jet.
HYBRIDS don't you just lov'em?
So, I like it so far!
How about you?

Hint....
You might find out what pin it goes into on the ECU. A little easier access but tricky to confirm what is doing all the time unless it's totally shot!

Also, Bye the way, if you have not found it out by now, the connectors are released by pushing down into the center of the spring wire which spreads the ends outward away from the tabs on the component. Then wiggle and tug it apart.
At least on other LH's it's done that way.

Phil

Phil and all,

It has been awhile since I posted on this issue because I thought I had the issue resolved. I originally posted about a stalling situation on my 83 245 (stalling when in neutral, sort of bogged down). I procedded to clean the air mass sensor and the entire throttle body, and after hooking it back up the car displayed sort of the opposite symptoms - in that after the warm up period the car went to a high idle and would not come off of it.

I then replaced the IAC with a new used part and the car has worked great for many weeks - I have probably driven it about 2k miles in fact. About a week ago, after exiting a 40 mile drive on the interstate, the car suddenly developed the high idle syndrome again. When this happens, the car is nearly impossible to start until you let it cool down, so I dare not stop for fuel, etc.

After this incident, once I got the car parked at work after this happened, it started up fine that evening and ran great the whole drive home. I used the car for another 2 weeks approximately with no issue at all, until driving today, when the car developed the high idle again.

Can anyone help me determine what this may be? It seems to be an intermittent issue. When I had the "old" IAC on the car, it would go to high idle anytime you drove it to operating temperature. Now, it has only done this twice out of dozens of trips with the new IAC. The car does have the original engine harness which concerns me (alternator and ignition coil wires have already been re-routed. Yet in my mind I feel that if it was a wiring issue I would see this problem all the time. I was originally suspect of the engine coolant temp sensor wire.

Very much appreciate any next steps anyone can offer. Many thanks. Love to keep this thing on the road but have no idea where to start investigating further.

Nice to hear you made progress and got it to run a lot better.

My only suggestion is that there maybe a wiring problem to the IAC.

You see, on this car the IAC it does not use a return spring and it has three connection pins. The later IAC's push against the spring with power.
It pluses power to modulate or flip open or shut the vane in the IAC per direction from the ECU.

What maybe happening is there is a break in one of the three wires and most likely the one that rotates or closes the vane. The IAC should rev the engine up, past normal idle and down ever time it starts up.
It could be a wire itself or some corrosion affecting the terminals continuity.

The next time it does it, try wiggling the wiring on the IAC or removing it and replacing it a few times
You can do this while it is running too fast.

Also there is that blue/pink wire that's used during basic idle setup that grounds the IAC into non operation or closed. I am not sure on that.
You might try that to see if it effects the IAC and not touch anything else. Who knows, it might be getting grounded in some way at times by it.
One would think it would make it idle lower unless it just freezes the IAC in its present position. I never pondered the possibility.

These wiring harnesses can do some weird things.

Electricity in itself is not a very good driver without excellent roads. The wider or thicker the better!
It loves to take shorter paths like going down two roads at the same time.
It can drop off a few buddy electrons towards another place or just stop dead in the middle of the road and yet it can obey all the traffic laws, of physics at the same time!

You are the highway manager. Doing one thing at a time with some logical troubleshooting plus time honored patience will win out though.

Thanks for the updates!
It makes thinking and writing about how things can happen more fun than just having tools to toss up in the air!

Phil

I just went thru this last week. I have an '83 also. I pulled and tugged too. Finally used a flat blade screwdriver and pryed it off. It came off pretty easy. Careful taking the hoses off. I tore one. I have been driving it without a IAC, placing duct tape over the respective openings andputting it in netural using left foot for brake and playing with the gas.
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Sandy '83 244 DL current, '90 240, '93 850 memories

I am going to remove and clean the Idle Air Control Valve. Having a bit of trouble removing the electrical connection. Does anyone have any advice for how to remove this connection? I have been pulling on it with no success and am afraid I will break something off. Seems there must be a trick to get this off that I cannot see or am not aware of due to the tight space with which to reach my hand under there.

Appreciate any help - thank you. Is there anything I should beware of when reinstalling the control valve, such as an adjustment, etc.?

thank you

Thank you all. I will remove the idle control valve and clean it. I found where it is on the car. Is there anything I need to be aware of other than cleaning the valve and hooking it up to 12v to make sure it functions? Such as is there anything I could screw up as far as an adjustment or is just remount it and hook up the electrical connection ? Thanks again

Also wanted to mention that while I mostly have a fast idle , i have noticed that on occasion the car will drop to a normal idle while driving , usually only to return to a fast idle upon accelerating again . Thanks again

Yes check the ICV and clean it.

It may be full of crud causing slow return to normal idle. It could cause your hard start too if it stuck open more than usual leading to improper air-fuel mix.

Also check your spark plugs. Cleaning your engine may have pushed all the gunk to be combusted thus fouling the plugs.

Hope this helps.

Amarin.

I didn't see anything about cleaning idle control valve.
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