I have very little experience working on non lambda KE cars.

Without an O2 sensor you should probably get to 0.0ma at idle. I think you should have no enrichment from zero except for airflow potentiometer initiated acceleration enrichment and temp sensor based cold enrichment. You should see decel fuel shut off -60ma on decel. You might look at the coolant sensor.

I do find it illogical for you to have 11ma EHA current warm without O2 sensors. That is a base zero car isn't it? The onlt cars I know of that aren't base zero are the early 190s and they are base 8ma because they can not go negative current.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Hi Chuck,


my major worry is that when I turn the engine off and take the key out of the ignition and lock the car, the EHA current remains at 11mA for serveral minutes. I don't know if this is normal?

Does anybody else know?

Tony

Update:

After much reading and research, I found a MB article which states that EHA voltages and current can remain for up to 15 minutes after switch off. I’ve carefully examined the wiring diagrams and pin 30a OVP relay, is connected to pin 1 CIS-E and is live/hot at all times but is fused via th10A fuse on top (OVP). So that now makes sense.

I removed the CIS-E unit cover and soldered a wire directly on pin 13 (02 sensor signal). When all powered up it measured 0.45V. Don’t know where the signal is generated. (Neither does local MB dealer) There is definitely no Lambda sensor fitted as I fitted complete exhaust including front pipes and just performed head overall and cylinder head gasket change)

MAS pins 12, 17, 18, 8, 11 are connected to CIS-E pins 11, 42, 3, 27 respectively. Pin 9 MAS to pin 45 CIS open circuit which is what I expected.

Connected meter to X11 pins 2, 3 KOEO read 28.9 % (engine cold) turned key and sat at 49.6% up to operating temp and beyond. I then cleared fault code 9 on CIS memory and took it for a drive.

With meter in car, only on deceleration from high speed did the % change and it rose consistently to 88.9 -89.6% every time. When I got home and checked memory fault code 9 also reappeared.

I also asked my local MB dealer if they could tell me the EHA currents measurements for my vehicle but the said the car was too old and did not have that information. – Great.

Does the fault seem to be a fuel pressure related fault?

I was going to swap the EHA with the one off the 103 engine. When I unscrewed that one there was no fuel pressure but as I tried to remove mine, fuel squirted out at high pressure until the pressure had gone (Both had ignition off!) I swapped them over and the EHA current was still around 11mA.

Is it normal to still have fuel pressure at this point after switch off?

Could the fuel pressure regulator be at fault?

Does the MAS unit only pulse the fuel pumps or are the on all the time during the engine running.

(The 103 300e has now gone so I can’t swap the FPR.)

Once again

Thanks Tony.

So they are faking out the CIS-E brain with a constant voltage, just like a proper O2 sensor's.

Some of this is OK - you are getting about 30% KOEO, and then you get a perfect reading of almost 50% after warm-up. Under deceleration, you are going to nearly full open to divert fuel from the cylinders. The problems are that you are not getting any enrichment during warm-up or on acceleration. Maybe the brain finds this illogical.

I think that you need to get ahold of the W124 CD for the UK cars to find out what the current should be. I would call the main number which is on the Mercedes UK web site -

http://www.mercedes-benz.co.uk/ and ask for technical support.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Thanks Chuck I give them a try.

I do get warm-up enrichment via the EHA its up at 36mA decreasing slowly until full operating temp.

Tony

I wonder why you wouldn't see that in the on/off ratio?

The 103.980 spec is 21-27 at 20 degrees coolant temp up so you are still in the 11 mA too-high-range.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Was this problem ever solved? I have the same problem - can't read out on/off ratio from connector X11, pin 3, because ratio is constantly @90% meaning "Electro-hydraulic actuator current implausible" or "Current at electro-hydraulic actuator out of range."

What kind of car?

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

MB 300CE-24 ´92. I believe the engine is 104.980 KE.

Can someone tell me how to get the fault cade from a 1990 300 sel?

Thanks
Ed...

You need to make an impulse counter, hook it up to the correct pins and count the flashes. I think there are a couple of posts on how to make one.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe