Idle problem seems to be fixed!

[Chadahar]

I have been troubleshooting a bad idle, no idle high idle, and an abrupt, though intermittent dying problem at idle. On slow down for a turn or a stoplight or sign.
I changed the OPR and it fixed it for about twenty minutes.

I noticed that when I would tap on the ICU when it was idling(high or low) that it would change (up or down) or die completely. ICU was suspect, but I could not rule out other things.
I bought a recently rebuilt ICU on Ebay. I installed it this morning.

VOILA! that seems to have worked. now starts and idles(first at about 1100, but drops back to about 900 (in park) almost instantly.) It now idles at about 600-700 in drive or reverse. Drove about 25 miles and it worked perfectly in all modes!
WHEW!
I really need it to idle right when I take it in to have the Smog test done. I feel really good about the car now, as I had the oil changed and they checked the spark plugs and all were firing right(they're new). All looked just like a good firing spark plug should look. Oil filter was TOAST! Can you spell falling apart! Car had had Castrol in it all it's life so I put that back in it (20-50) Am thinking about Synthetic after i get the little oil leaks (none underneath) fixed.

Now to get the CCU fixed. I tried to re-solder connections but I think it was toast before I started(some traces burnt through, Nothing working but one motor(heater blower on low??? and crosstalking I'm sure)so I have to get another. Blower motor OK as it worked intermittently, either with AC or Heat. I also bought a good Heater/AC relay
Before I put in the new ICU I took the old CCU out so as not to take a chance on a faulty CCU doing damage to the OPR or the ICU.

One by one I'm getting through the small problems on this fine old car. I am a happy camper today!

[CamelotShadow]

Good news!

I found out I have a bosch air idle control valve.
Same place but sits upright
It was that alum cannister I suspected.
Must have been a later addition as I still have the empty socket plug sitting there for the ICV

Car now is almost perfect

except the hard warm/hot start

Still has a hi cold start idle
but thats only when cold & in park

It drives fine...

Took it out yesterday
first day after breaking & bypassig the TVV
& it runs flawlessly
cept when you have to restart it hot...

OOOh well,

Least its working fine

Old machines
sometimes a bit easier w less computer headaches...

I have seen ICV for $200
They retail $800 or so I heard
arrghhh

You clean your old one out?
That sometimes helps...

[Chadahar]

Yep I cleaned my ICV twice, once with carb cleaner and once with WD-40.
Look on Ebay for an ICV, haven't seen one like yours but I haven't been looking either, I know they have ICV's like mine on there. So Far so good with the parts I have puerchased off Ebay. One guy in in Sylmar, the others are out of state. Guy in Sylmar has good used parts.

[CamelotShadow]

Well, its good you solved yours

I think my ICV is fine
I saw an old listing
one like mine on ebay
sold for $2.99

LOL

My wierd idle is just on cold start up
its high in park only
I can live with that
but wondering where it is steming from

[Chadahar]

Tap on the ICU smartly and see if the RPM changes, if so the ICU probably has problems. That is what mine boiled down to. Either there are Cold solder joints or there is another problem. I kept my old ICU as a "get home" repair if the good one takes a dump and I'm stranded. Same with the old OPR.

Happiness is a MB that'll start and idle like it is supposed to.

[CamelotShadow]

Originally Posted by Charlies84380SE

Tap on the ICU smartly and see if the RPM changes, if so the ICU probably has problems. That is what mine boiled down to. Either there are Cold solder joints or there is another problem. I kept my old ICU as a "get home" repair if the good one takes a dump and I'm stranded. Same with the old OPR.


Happiness is a MB that'll start and idle like it is supposed to.

My feeling is with those things
esp if they respond to tapping that
its an electrical connection in the unit

I changed all of my ceramic fuses
I got my old OVR too
New one didn't seem to fix anything
but those things are a sure bet to give some problem after 100K
So a new one is insurance

Mine definitely idles at lights better

I changed alot of old vac hoses
I cahnged the rotor & dis cap
So any of that could & should have helped

I;m also running a bottle of techron cleaner

Yep happiness is a benz purring down the road...

[melroseparkrags]

hey brothers i dont want to sound like a goof but can you descramble your texting of the parts your talking about, the reason is im having these problems myself and if i knew what the parts actually were ,i might be able to check them out, its tough getting old ,thanks in advance

[CamelotShadow]

Originally Posted by melroseparkrags

hey brothers i dont want to sound like a goof but can you descramble your texting of the parts your talking about, the reason is im having these problems myself and if i knew what the parts actually were ,i might be able to check them out, its tough getting old ,thanks in advance

ICV- idle control valve

OVR overload protection relay

TVV themo vacumm valve switch

Yeah, our benzes are not getting older
there getting classic

Good Luck, Bro

[mercmad6.3]

Originally Posted by CamelotShadow

Well, its good you solved yours

I think my ICV is fine
I saw an old listing
one like mine on ebay
sold for $2.99

LOL

My wierd idle is just on cold start up
its high in park only
I can live with that
but wondering where it is steming from

What you have is an auxliiary airslide from a very early V8 either a 380 or possibly even older such as 450 or 3.5 with djet injection.
With this the idle should be high at cold then slow down to normal 500-650 RPM.
Big problems arise when the aircon clicks in because that idle device is "static". the electronic devices speed the engine up as load increases.
You have probably found the idle dropping really low as the car gets warm,you are in drive,air going at the lights and you want to make a turn...right?.
Someone has fitted it because a fault in the electronic device has caused a high idle and they either didn't know how to rectify it or were being cheap.
The heater type airslide such as have will work oK ,as long as remember that it is very limited in it's application.

[slk230red]

Originally Posted by mercmad6.3

What you have is an auxliiary airslide from a very early V8 either a 380 or possibly even older such as 450 or 3.5 with djet injection.
With this the idle should be high at cold then slow down to normal 500-650 RPM.
Big problems arise when the aircon clicks in because that idle device is "static". the electronic devices speed the engine up as load increases.
You have probably found the idle dropping really low as the car gets warm,you are in drive,air going at the lights and you want to make a turn...right?.
Someone has fitted it because a fault in the electronic device has caused a high idle and they either didn't know how to rectify it or were being cheap.
The heater type airslide such as have will work oK ,as long as remember that it is very limited in it's application.

Hey, would this type of ICV be considered cheap? If all else fails, go to Home Depot.



It's a "Home Depot Gate Valve Special", requires no power connection (note the dangling power connector) and YOU can control the idle speed.

[Chadahar]

ROFLMAO! Cold Milk thru the nose all over the keyboard! That is some fix albeit cheap.

[slk230red]

Originally Posted by Charlies84380SE

ROFLMAO! Cold Milk thru the nose all over the keyboard! That is some fix albeit cheap.

Glad you enjoyed it! I borrowed the photo from someone that likes to be in control of his idle speed. He likes it, so I guess that's all that matters.
Whatever floats your boat.

[CamelotShadow]

Originally Posted by mercmad6.3

What you have is an auxliiary airslide from a very early V8 either a 380 or possibly even older such as 450 or 3.5 with djet injection.
With this the idle should be high at cold then slow down to normal 500-650 RPM.
Big problems arise when the aircon clicks in because that idle device is "static". the electronic devices speed the engine up as load increases.
You have probably found the idle dropping really low as the car gets warm,you are in drive,air going at the lights and you want to make a turn...right?.
Someone has fitted it because a fault in the electronic device has caused a high idle and they either didn't know how to rectify it or were being cheap.
The heater type airslide such as have will work oK ,as long as remember that it is very limited in it's application.

That's not nice
wonder who mickeyed with it like that

It was owned by a Rich DR
Well are there really poor ones..?

Maybe the curbstoner?

Haven't run the air yet but it idles fine in drive 650 700 ish

What would it intail bringing it back to being right?

[Chadahar]

Would being a Euro cause it to have the airslide instead of the ICV? but you have an ICV connection in your wiring loom too. HMMM!

[mercmad6.3]

The gate valve is exactly how it works....except the factory set up uses engine heat to open or close it...

good ida that,except that as mentioned above you could find a proper one on ebay for $2,whereas hardware shop prices are around $10.

That's not nice
wonder who mickeyed with it like that

It was owned by a Rich DR
Well are there really poor ones..?

Maybe the curbstoner?

Haven't run the air yet but it idles fine in drive 650 700 ish

What would it intail bringing it back to being right?

I wouldn't worry unduly about it. To set it up right,get the engine hot,and with the aid of an assistant,put the car in drive with the engine IDLING ,turn on the air,then turn the large plastic screw slowly until idle sits at 650 rpm. It will idle fast in park ,without the air but who drives a car in park?.
To convert back to stock you need to find both the airslide and a control module,if it's missing from the car. I see them on US ebay quite often. But be aware that you must get the correct parts for your car.right hand drive and left hand drive cars have entirely different parts.