Hi folks,

I have tried all the tricks I can think of with this.

Everything is clean and adjusted (this problem arose when throttle body was cleaned) the cis was open circut and has been replaced, but still the same 1250 rpm. Sorta like if you disconnect the tps it runs fast.

Throttle plate and tps is correctly adjusted, have swapped a tps that I know is good and fixed any sign of harness trouble.

Have checked for vac leaks, nothing. We have vac at breather hose from flame trap, the 1/2" hose that connects to intake tube opposite cis intake.

When cis intake hose is pulled the engine stalls and when breather is pulled it drops about 300 rpm, back to 950 rpm. The throttle body was seriously crudded and maybe someone tried to cover the problems by making adjustments.

I have since returned it to factory settings so I'm getting short of places to go on this now and would greatly appreciate your help. After checking the archives and faq and didn't find the answer there I'm hoping someone has some ideas on it.

Thanks to all for taking the time to read this.

A friend of mine had a intermittant high problem. The cause was the connection to the ECU temperature sensor. When the connection is open, the computer thinks the car is cold & the car car idles much higher than normal. This sensor is a little hard to get to. Hidden back by the flame trap under the intake manifold. If you need test point & have an ohm meter, you can check the resistance at the ECU connector.

Tony,

The ecu temp. sensor might be worth looking at.

The thing idles nice now but is set up as a carby type manual setting, not auto control.

My friend took the car home this morning on a 6 hour trip,(I bought the car for him) so I won't see it again until xmas when they come back.

Hopefully we will find the problem before then, so I will check the sensor on one of the other cars and get him to to check his and compare readings.

I can see that this is a problem for a few of us so I shall put a bit of time into it and see if we can sort it out.

How do you manage a 3000 rpm idle with an auto tranny?

Thankyou all for your help and when I find it I'll let you know.

Regards. Ian

I am the proud owner of a 1986 240 sedan that had a similar problem.

Idle was fast at times and unsteady. Also the engine started running rich. (black smoke out the exhaust).

I checked obvious things that you have checked. Finally took it to a shop that is known to be savvy.

Problem found: Engine wiring harness. Apparently these were made with wiring insulation that breaks down over a period of time and then the wires begin to short here and there.

I remembered seeing something in a IPD newsletter about replacement harnesses and why they go out.

Ordered a replacement from IPD in Portland, Oregon USA and the shop installed it for me.

On the road again. This I assume happens often given the aftermarket availability of this harnesses.

Wiring harness is not out of the picture entirely as yet, I have repaired it as there were only a few that were affected that I could find.

My latest research tells me the cis and tps are not getting a signal, more research needed there.

ATTENTION ZEE!!! you might have the same problem. Temporary fix to get idling under control, I have put a plug in the tube from intake near throttle body to air idle valve (cis) and reconnected it, do it so you can easily remove it when we find the solution to this. All looks normal, you can raise or lower speed by idle screw.

Now the car starts and idles nicely around 800 rpm and has no performance problems.

The cis and tps are only in the picture when you come back to idle anyway, I think, but could be wrong.

If you find anything to the contrary please let me know.

I'll post it if I find the proper fix.

Ian. 89 745T. 89 740T. 82 244. 83 240.

PS: Paul your rich mix was probably wiring to your mass air meter affected, only a hunch.

Wiring harness is not out of the picture entirely as yet, I have repaired it as there were only a few that were affected that I could find.

My latest research tells me the cis and tps are not getting a signal, more research needed there.

ATTENTION ZEE!!! you might have the same problem. Temporary fix to get idling under control, I have put a plug in the tube from intake near throttle body to air idle valve (cis) and reconnected it, do it so you can easily remove it when we find the solution to this. All looks normal, you can raise or lower speed by idle screw.

Now the car starts and idles nicely around 800 rpm and has no performance problems.

The cis and tps are only in the picture when you come back to idle anyway, I think, but could be wrong.

If you find anything to the contrary please let me know.

I'll post it if I find the proper fix.

Ian

PS: Paul your rich mix was probably wiring to your mass air meter affected, only a hunch.

Someone else and I have been having this problem -- only worse.

my '86 is "idling" at 2500-3000 RPM!!!!

It would start, run as fast idle for a split second, begin to lower into normal idle speed, then ZOOM up to 2500-3000.

It actually idles better with the connector to the ICV disconnected. Grounding it to the strut tower by way of the blue-white wire makes no difference. However, even with the ICV disconnect, it still sould kick up very fast.

I have tried three ICVC's on it and it still zooms.

The other guy suggested he thinks he reversed the connectors for the Idle Control Valve and the Throttle Position Switch.

I didn't think I had done that, but, I was desparate, so, I tried reversing them.

This got my idle down now to about 1000-1200, without the extremely fast idle.

But I don't know if this is actually a solution. The connectors now appear "wrong" for the positions they are reversed to (pardon my grammer). Also, the idle is still about 950-1200, so, it is as if the ICV is merely in disconnect status.

First of all I want to state that I have the B23F engine with LH

2.0. Not your B230F with LH 2.4 controller.

I am sorry I was so inarticulate. I would never suggest swapping

the ICV (Idle Control Valve) and Throttle position switch. I is

something I inadvertently did when I replaced the wiring harness.

I have tried to remove my temporary plug from hose upstream of the

throttle body that goes to the ICV. Then I removed the electrical

connection to the ICV. I am sorry to report that my engine races

up to 3000 RPM just as before. This could be from a bad ICV, but

I have replaced it (only once not twice like Zee)

I too am at a loss to understand why my car wants to run at

this high idle. If I hit the accelerator for a second, and

let it drop back to an idle, it seems to want to control the

speed at about 1000 RPM for a second, and it takes off back

up to 3000 RPM.

Did yoou then swicth those connections back?

What happened?

(evidently you now have the correct wires on their proper sensors, so, I take it something else is the probpem?)

Yes something else is the problem. I wish I knew what it

was just like you. I am at a loss to explain the engine's

behavior and just was agreeing with you that I had a similar

problem.

I am now running with the plug in the air inlet to the ICV

(Idle Control Valve) to keep the system idle at a resonable

level. That is the only practical advice I can offer. It

works, but it is not a "fix" only a "jury-rig."

I tried your suggestion to disconnect the ICV wiring, and

that did not help. It did for your engine. I don't know

if that is because we have a different root cause, or the

difference between the LH 2.0 and 2.2 systems changes the

behavior.

I know it may sound too ridiculous but have you simply tried adjusting the idle screw down??

How about the linkage that connects the throttle body to the accelarator, maybe the previous owner ajusted that (turnbuckle) to compensate for a gummy throttle body.

Geeez what else is there? You seemed to have run the gammet

Tony,

All the settings have been checked and restored to base except the idle screw, it's in as far as it will go.

I only bought the car last thursday for $2100 it's a nice car and has been inland all it's life, no rust (has the m46) all service history has been kept up to date, average price is $4500 to $6500 over here for that model.

Someone has had this problem with this car in the past and adjusted things to cover it, I intend to get to the bottom of it. I'll let you know the results. The throttle body was well crudded, had not seen a clean for a long time.

Zee I read your posts on "high idle whooooas" I was wondering if you found the problem.

Did you see the movie "THE TERMINATOR" (1) I shall adopt the same attitude as he had until I find it. Still open to any clues out there.

Thankyou again. Ian

I wish I could help out with an answer, unfortunately I cannot but I am experiencing the same problem. I blew up my engine and had a local shop take a month to put in a new used engine. he pointed out my wiring harness was burned out, I am assuming from the looks of it, it was not burned and is just brittle insulation on the wires as described, he wrapped the wires for me, but with this other engine in I am also getting a battery light every time I turn the car off. This leads me to believe that my two problems are connected. unless there is any difference in the wiring harness from a b21ft and whatever engine I have now (I really have no idea what was put in It's either a 230 or something else, If anybody has a good way to tell I would b thankful)

I hope this helps somebody that is a little more familiar with this model, keep us updated.

Tom LeRoy

Ok, here's an update on what I've experienced so far today I inspected my wiring harness and found my mechanic wrapped most of the wires so I re-did them just so I could be sure it's not his fault, but I found nothing to help my woes. I still am having surges but now when I get them if i push the group of wires that dissappear under the intake manifold the surge stops till i either let go or push it far enough that it dosn't cone all the way back to it's original position.

I think I still have the same engine B21ft just now I have the original turbo not intercolled does that make sense?

hope this helps. keep us posted on any fixes please.

tom