Tough question 4 KE Jetronic expert - PeachParts Mercedes-Benz Forum

ThomH · #1 04-08-2004, 12:35 PM

Hi

when I unplug my idle control valve, the idle revs go down. Actually they should go up. I already tried a new ICV, however, the problem remains.

Do you have any explanation why this happens?!

I am not sure if this has actually any effect. But since I would like the idle to get a bit smoother, I am trying to remove all potential causes. But here I don't know what to do.

Cheers
Tom

sbourg · #2 04-08-2004, 01:21 PM

I'm no expert, but why do you say the idle should increase when unplugged?

Steve

mbdoc · #3 04-08-2004, 03:58 PM

On MB's with that system the idle speed will increase ONLY on the M116/117(V-8) engines.

What model car are you refering to?

ThomH · #4 04-09-2004, 04:55 AM

Now you confused me. Sorry, it's a M103.982.

I just had a look, where from I had this info but couldn't find the reference. Somewhere I have read this. However, this could have been related to the M116/117. It only makes me wonder that the expert mechanic around here also expected it to go up. He inserted a new ICV for testing but this didn't change anything. Also I don't find a reference that this should happen with a M116/117. I just had another look in the MB workshop manual for the KE, KA and the electronic type.

Stupid question but are you absolutely positive that the increase should not happen with a M103?!

Cheers
Tom

PS: would be good as I don't know how to help this problem, would be bad as I would have to find another cause for the slight shaking of my idle...

ThomH · #5 04-09-2004, 05:48 AM

Hi again

I had another look in the manual and now I found it at the general KE description. Also with the M103, the ICV has a higher cross section with no voltage applied than with the idle voltage pulse.

So, any clue?

(Please keep in mind that the problem is not with the ICV. The proper one showed no difference. I would imagine that the ICV does not get sufficient air supply and hence has to open during idle more than in should (and with a bigger cross section than with no voltage applied). So far I did not see why it shouldn't receive enough air. However, thinking of it, I will have another look. But still, if you should have another idea or a more detailled one why it shouldn't get enouph air, this would be highly appreciated!

mbdoc · #6 04-09-2004, 08:01 AM

The idle control on a M103 engines operates by of a "duty cycle" voltage signal. Inputs to the CIS-E ECU & an internal map in the ECU determines the correct duty cycle, should be 30%(approx +-).
ON a good running M103 engine the engine idle speed will drop when you disconnect the electrical connection when the engine is running.

WHAT is the engine doing?? Stalling?

ThomH · #7 04-15-2004, 05:19 PM

I wouldn't call it stalling. But it's a pretty rough idle with the icv unconnected.

I just wonder, because the workshop manual says, the revs should increase since the emergency cross section (when no power supply) is larger than the stanard idle cross section.

However, I noticed that the EHA valve is leaking. I will start a new thread for this

Cheers
Tom

joe p · #8 04-15-2004, 08:28 PM

With the exception of the 116-7 engines all KE cars go down as the natural posistion of the valve is shut. the 116-7 engines natural posistion is partially open for some obscure engineering reason.

A EHA that leaks fuel is simply broke, get a new one.

Joe

btw, 103's will do wierd idle stunts with the idle micro switch bad or being missed by the linakge.