91 300E M103 - Starting Issues
 

My wife's 300E has had random starting issues since we purchased the car over a year ago.

Mostly when cold, and it has the feel of lack of fuel. Sometimes after starting the idle can be rough until accelerator pumped, then it runs smooth.

I am about to get it evaluated but would appreciate any ideas and feedback.

Check following:

Distributor Cap.

Rotor.

EHA on side of Fuel Distributor for leaking.

EHA should be adjusted per Mercedes Factory
Service procedure.

BOSCH KE3-JETRONIC MIXTURE ADJUSTMENT


300E Idle Mix ok, but when revved goes off the scale to rich. - MBWorld.org Forums



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Don't mess with the EHA valve. Do the dist cap and rotor first. Then, plugs (only copper, non-resistor)and spark plug wires (if not fairly new already). The EHA valve is probably ok. It's also a pretty expensive part ( like $350.00) and the adjustment is very easy to screw up and not be able to get back to starting point (I ended up buying a new one and it wasn't the issue...ouch). Report back after you do the above.

AU Contraire MON Ami....if the EHA is leaking, it needs replacing....period. If the c/o % is very low after setting ratio/on-off values to 45 to 50 % then the EHA ratio needs adjusting as per my link above.

If ever you adjust the Allen screw in back of the EHA, then yes...be very careful not to lose the original setting as the Allen is quiet loose and easy to turn.

The EHA is everything to smooth engine running, starting, acceleration. ...providing upper to lower pressure is correct.

Cap and rotor are usual suspects, I agree.



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Thanks, I will start with the cap & rotor and move on from there.

Hmm
 

The random nature makes me suspect a failing:

Crankshaft Sensor, Rear
MB# 002 153 92 28

and/or

Overload Protection Relay
MB# 201 540 37 45

and/or

E.H.A. Valve (Electro-Hydraulic Actuator)
MB# 000 070 39 62

Mercedes-Benz Driveability
Evaluating Electronic Engine Controls
by Steve Brotherton, Import Specialist
Published in: ImportCar, February 2001
PeachPartsWiki: Mercedes-Benz Driveability

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I had some cold starting issues however they were semi-consistent. I bought a fuel pressure tester ($75-90) and verified my system pressure, lower pressure chambers, etc and found they were at spec.

I found my lambda tower was out of adjustment. It was running very rich (low % numbers) I readjusted it to 45-50% at idle.

It worked like a charm no more starting, stalling, and restarting or needing to push the gas down to keep it running.