High Idle Club New Member - Help!

[shayes]

Having unwittingly become a Member of the W126 High Idle Club (not everything gets diclosed by e-bay sellers!!) I like the Car and would prefer to solve the problem.

I have read most of what has been said by Members about the problem both here and in the USA.

CAN ANYONE HELP?? If you have owned a W126 Series (my car is a 500SEL -having sadly disposed of my 500SEC) 1985 model.

DO YOU HAVE AN ICV which you took off your Car having purchased a new replacement, only to find that this was NOT THE PROBLEM?

If you have a redundant but (possibly) perfectly good one in your Garage, can you please send it to me strictly on the understanding that I will return it and pay your postage. I have a 100% positive rating on e-bay for over 200 item sales (which you may check) so I give my word that the item will be returned and all postage costs reimbursed to you.

By checking an alternative ICV it may tell me if this is the problem part or it must be the vacuum or a voltage matter. I have already removed the existing, and found very little carbon came out using Car and throttle cleaner. The Car has only done 103k, one owner, miles. The Electric part with fuse seated in the fuse box looks brand new. Vacuum lines I have not checked in detail. The headlamp adjustment seems to work via the vacuum. doors lock OK, Am waiting on a Vacuum guage but confess to being a bit out of my depth when it comes to electrical testing etc

Did discover that the Air Filter had started to split at the corner nearest to the intake and thought "this must be it" running weak. Having put in a piece of card in the area it did not solve the problem.

Problem is, starts OK runs from start at about 600rpm when cold in P. Drives OK but possibly when in drive RPM does not fall below 1100rpm so going down to 30mph requires breaking. When engaging N or P when hot revs rise to 1600rpm.

SO, HAS ANYONE GOT A SPARE PURELY FOR TESTING PURPOSES. My details will be given to anyone who can help. Direct e-mail stuart@south-of-france.info

THANKS

 

[shayes]

Just had a belated thought.
Has anyone used a steam cleaner jet to try to clean out a Idle Control Valve??
Not clear what is inside but can get into it more via the side vent.

Read that some people get loads of junk out of it. I soaked it for a couple of hours and frankly got virtually nothing out - even had to wipe the inside of the hose ends with a rag to get the soot off.

Can be blow dired with a hairdryer after blasting.

Am I going slightly mad?

 

[Mikesmerc]

Stuart, I had the same problem with my 1990 560SEC and I bought a Second hand valve for 80euro from a breaker. Sorted the problem.
Rgds
mike

 

[shayes]

That's great Mike,
Just done a deal for a second hand one for £25.
Here's hoping!
Will let all know, later this week.

 

[shayes]

Sadly the replacement ICV is not quite the same diameter aperture to the rubber on the Engine and so back to the seller in the hope that he will supply the rubber and that the Engine connection will be the same as my own!!
Frustrating and so decided to steam blast the original one. Certainly cleaned it out better than Carb cleaner, question is, has it done any good.
Too eager to understand where the moving parts are in the mechanism and so admit to doing a little tapping in the end.. Probably not a good idea. Will see tomorrow.
The other bad news, and its been a day of disasters, is that phoned Euro where the item is quoted as priced "from £81.75" to be told they have none in stock, none on order , and the price will be £286.00 + VAT!

Going to have to re-invent the wheel as Bu.....d if I'm going to pay that much! Must be an alternative. Think I read that some guy in the States bored a 5mm hole somewhere??? Don't ask me what that was all about - will have to find the thread.

 

[Myros]

try immersing it in brake fluid overnight

it certainly gets a lot of crud out. it also dissolves the part number on the sticker. I ended up with one from Mercman, £100-ish and it worked fine, still does.

 

[dougtsc]

Could try here:

http://www.247spares.co.uk/carparts...t_condition=used&part_name=idle-control-valve

 

[Mikesmerc]

Keep looking Stuart, plenty of breakers out there and quote the Bosch serial number to them, there are a few different types. These units are very often not servicable.

Regards
Mike

 

[shayes]

Could try here:

http://www.247spares.co.uk/carparts...t_condition=used&part_name=idle-control-valve

Thanks Doug

 

[shayes]

Well I've got a replacement Idle Control Valve but no change so unless its duff then something else is at fault.

A black box under the dash (the control unit) I'm told may be the culprit, but first need to test the Coolant temp switch. Is it as simple as just straddling the female connectors with an electrical tester when the car is cold and first idling?

What goes wrong with the "black box" is it dried out solder connections? Is this thing a sealed unit?

Trying to avoid going to Merc specialists if I can.

 

[shayes]

Not yet got the problem licked but will bore you with the story so far.
Interestingly, when I disconnected the Thermo switch to check, it made no difference to the High Idle situation when I drove the car a few miles. Strangely, however, after stopping briefly, I drove to a Builders yard to collect some things, and the idle speed behaved CORRECTLY.
I did only one thing abnormal, which I thought at the time could not have caused the correction. I switched off the Car whilst stationery, in the drive position.
Having used the car several times since with the thermoswitch re-connected the High Idle problem continued until yesterday when I tookthe car to Mainly Mercs in Colchester a distance of some fifteen miles me. It's sod's law, en route, having found the high idle recurring at various stopping points I was tweaking a heater control and felt a small surge in the throttle system and from then on, until my arrival at Mainly Mercs the car behaved properly. So!!! drove home - everything fine..
Today, high idle again!!! BUT, tried switching off in gear when stationery and correct idle situation resumed. I guess it must be a Vacuum thing causing the problem or the car has a Poltergeist as someone suggested? Anyone had a vacuum problem and if so, where best to look please?

 

[42847]

high idle

two years ago my v8 w107 tickover would rise from 700 to 1600rpm when it warmed up...i tried everything...then i removed a vacuum pipe from the distributer area and its been 700rpm ever since with no side effects ...thats 2 years ago....is this any help?

 

[shayes]

Presumeably from the Vacuum that is attached to the distributor which is a sort of advance /retard mechanism for the distributor, I think. Maybe you dislodged some dirt in the tube but interesting that its removal corrected the problem.
It is an irritating phenomenan as on some days the car idles correctly. On others I have to apply the brake to keep it below 30MPH. I have looked under my Dash and don't find a Control Box which I want to examine as thought to be the cause? Only largish box (7 x 4.5 x 1 inch) under there is an Aluminium box with orange connector which someone tells me is cruise control.

I also wonder if the vacuum system operates the Heater vents and may have something to do with the problem. Must get someone to check the system as its driving me nuts!

 

[television]

the vacuam system does operate parts of your heater system

Malcolm

 

[Myros]

i think it might have been the exhaust gas recirculator

it has its own diaphragm unit down on the left hand manifold, looks just like the advance/retard unit on the dizzy. If the system were all fouled up or not right, it would send the idle up as the engine would not be getting as much air. Disconnecting it "restored" the balance. If you had disconnected the distributor advance/retard, you wouldn't be driving anywhere in a controlled fashion.

 

[shayes]

Thanks Myros I'll look at that other diaphram.
Funny thing when I owned an SEC I discovered that one of the springs in the Advance /retard mechanism in the dizzy was missing. Eventually managed to find an alternative spring but it did not seem to affect the engine at all, from what I recall. How such a thing could go missing always baffled me!

 

[shayes]

Car warmed up, I stopped at the mechanics and high idle occuring. Stopped engine and removed vacuum pipe from Diaphram near to exhaust manifold - restarted engine - high idle continued, so replaced. Took off vacuum pipe from Dizzie Diaphram, started up - same high idle - replaced.

Not found a Control Unit under my Dash as on earlier SEL's (85) and Mechie said he thought maybe the Kickdown black box in the fuse box is the controller of idle, petrol, etc.

If not, can anyone tell me where my Control Unit is situated?

Thanks.

 

[shayes]

Discovered the black Idle Control Box under the Dash (AFTER ALL!). Took out and see that it's a Mercedes replacement part 04/97. Looked in pretty good order though could see that someone had been "at it" by the fact that the nut holding the cradle was rounded and the cradle bent at one end. also, only sitting in place instead of bolted each side. Made it easy to get out. Anyway, cleaned pins but no change to High Idle - until switch off car when stopped and still in "Drive" position. Strangely, when I restart the car it idles at the 600rpm rate. So whats the fault? Have a s/h Control box en-route to me and the guy suggests that the "lock out Switch" may be faulty. It stops the Car starting in Drive position and does connect to the control box. ANYONE HAD ANY EXPERIENCE OF A FAULT WITH THIS PART?
Cheers

 

[television]

The idle control module is a common fault for high idle othe than a sticking idle valve.

If this solves your problem, If you would care to post the old one to me I will test it, and see what goes wrong, repair it for your and return it free of charge.

Malcolm.

PS I would take out the second spring in the distriutor, though it may have spare lugs, two were very seldom fitted, this has nothing to do with iddle.

Malcolm

 

[shayes]

Thank you Malcolm.
I have replaced the ICU with an older and grubbier looking version of the same AND IT HAS SOLVED THE PROBLEM - no more high idle. I will if I may take you up on your generous offer and send you the original unit for your expert inspection. Have sent you an e-mail direct, and if you would like to let me have your address - maybe a New Year job with the bustle of Xmas.

Thanks again.
Stuart