Hi everyone. New to the forum today. Thanks to all for what I hope will be some help. I have a 1994 C220 and the engine stall on a regular basis, say when approaching a stop light. Th dealer read the codes and tells me my alternator might be week, but the code says it is the Idle speed actuator. THe actuator cost over 850 bucks from the dealer and I can get one for about 460 from a parts store. How tough a job is it to replace? Thanks to all.

PB

 

I am not familiar with this particular model.

But the price for this item should be about fifty bucks.

They are generally pretty simple to change. The difficulties are that the engineers seem to have to out do themselves on cleverness of the electrical connections, they are usually a Rubic's cube of a puzzle, so use patience there, and many times the screws holding them in place are well frozen into position.

Before I would change one, especially at thei price, I would disassemble and clean the throttle body assembly. The idle Speed Control, Idle Speed Actuator, Idle Air Motor, etc. there are a milion names for it, merely moves a plunger between two openings in the throttle body. That gets carboned up so the plunger does not move freely. often times a new AIC will not cure the problem and a perfectly good AIC gets thrown away. In conjunction with this is the TPS, the throttle position sensor, also generally a fifty dollar item. It merely tells the computer how far the throttle is opened. It does this by varying the resistance, so you have a probe sliding across a resistive coil, just like the fuel lever sender in yout gas tank. They wear out.

I did a search for your part on Autozone and it was not available there. Good luck

 

Hi pbarth,

Welcome to the forum Hope you enjoy your stay.

Any of the following items can cause stalling:
EGR Control System, MAP Sensor, Throttle Position Sensor, Crank Angle Sensor, Vehicle Speed Sensor, Air Intake Sensor, Air Intake System, Fuel Supply System, Electronic Accelerator Actuator, Cruise control/idle speed control actuator and so forth.

When problems like this start to happen, I often ask people how long has it been since the car had a FULL tune-up (full meaning all filters as well as the usual stuff) and I am amazed at the amount of people that say I've never done one, then they wonder why the car is acting up.

I am by no means saying that you are one of them, so please don't take this the wrong way. If you can, please give us an idea of the history of the vehicle maintenance wise, and it should help to give you a more conclusive answer.

Start by checking the connections on your crankshaft position sensor. Sometimes they come loose and cause your problem, also it doesn't cost you anything to do so.

Then, if a FULL Tune-up hasn't been done in a while, I would perform one, then clear the codes and see how the thing runs, that way you can eliminate those items from the equation and start to work on the "REAL" problem if indeed one still exists. And if the tune-up wasn't the problem, then when you do get to the culprit causing you the headaches and fix it. You'll have peace of mind knowing that you can go for many more miles without worrying about the engine's state of tune ... (of lack thereof)

Book shows 1.7 hours labor to replace the Idel Speed Actuator Valve

Hope this helps.
TJ

 

Yikes, 1.7 hours, an eternity for many engines.

I would like to offer a diffetent opinion on the crank shaft position sensor. It has been my experience if that is somehow or other compromised, the motor will just plain not run. So I would not look there first. Others may have adifferent experience, and my experience is not with MB. I can never disagree with checking things that do not take much time though. You always want to start with the easy things. That way you may not have to do the hard things.

In the original post the poster indicated that the codes indicated the IAC. So that is where I would start, but you will be chasing your tail if the routine maintenance items need doing. Also, just because a code appears, that does not mean the sensor is bad. It may also mean that the sensor is accurately reporting what the condition is.

 

Thanks to all for your input. I'm still working the issue. The problem is getting worse. It died at every stop light today on my wifes drive home. I did replace the overload protection relay a few days ago. That didn't help. I did a little research and it looks like the plugs have about 44K on them. The were replaced at just under 40K and the car has about 83 k. I'll replace them tomorrow. I doubt that will help, but it is probably time. I'll get a look at the wires and boots then. I'm trying to approach this by working the little things first that need attention anyway. I'll also be checking the battery cables tonight, cleaning etc. Looks like the battery may be 5 years old also! It still cranks strong...More to follow and thanks again.

PB

 

have you tried SL600_Cruzin advise to check/replace the crankshaft position sensor first?

 

Sleep, no I haven't checked the crank sensor. Mostly because I havn't a clue where it is or what is looks like! I don't have any manual yet, so I'm flying blind here. The car has performed very well for the last 2.5 years and 12k miles. The car has reached the stage where it shouldn't be driven anymore. I've looked closely at the Idle speed actuator assembly, but I don't know how to disconnet the linkage at the bottom and I have no idea how to get my hands down to where the harness connects under the intake manifold. Maybe from the bottom....

Thanks to all,

PB

 

the CPS should be between the engine and transmission bell housing...from the top side.

 

Here's a picture of it's location



[IMG]local://upfiles/5574/57AF9D8721514E4187962478A4B67E1E.jpg[/IMG]

[IMG]local://upfiles/5574/D4611C1725F04A4EBCC30BB46D0326E5.jpg[/IMG]

 

Thank Cruzin,

I haven't been able to find it yet from the top. The pictures aren't exactly that of my motor, but it gives me a really good idea of what to look for. Thanks again.

PB