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Old 08-23-2005, 06:59 PM
Registered User
Join Date: Jun 2005
Location: Hopkinsville, Ky
Posts: 107
Exclamation hard start.

I am having trouble starting my 91 300e. when i turn the key the car cranks but it does not catch at times and when it does the idle is so low that it usually dies right after. i normally have to give it gas and then it will start up and run fine. although the start up idle is usually 1000 rpm or slightly less(i had to clamp the intake hose on the idle control valve). i have replaced the spark plugs with the recomended ones in the manual. and i replaced the distributor rotor. i have not replaced the wires though. the wires are bosch premium i think. i also smell fuel odors under the hood when i start the car. the car has 200,000+ miles on it so i believe that some things may need replacing. FYI i also have transmission problems, could that be the sorce of my problems, or a fuel pump going bad or leaky EHA and possibly injector seals or mabey something else i dont notice? all imput and advice welcome.

thanks in advance.

Last edited by masonn300; 08-23-2005 at 07:08 PM.
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Old 08-23-2005, 07:23 PM
Machine man
Join Date: Jul 2005
Location: Friendswood Texas
Posts: 32
Tough one.

Without asking you 50 questions here goes.

1. Have Oxygen sensor checked or just replace it. It did wonders for my 175,00 mi 1988 260e. O2 sensors or Lambda sensors can be damaged from an engine burning oil (thus the new one will go out as well) also driving through high water and the engine stalls. (thus water in the tail pipe to the O2 sensor will damage the O2 sensor.) and they just clog over time and don't respond as fast as they need to for your car to run smoothly.

2. Try running Premium Chevron with Techron through it this could not hurt anything. Especially with the miles on it.

3. Remove the resistor. Tie wrapped on the AC line next to the fender well drivers side. I removed and what a difference. Car starts first time everytime. do a search at this forum for resistor and there is a lot of info about it.

I was having same problem as you are describing. However I did not smell the fuel under the hood as you describe but I am a smoker and I don't smell thing too well. I replaced my O2 sensor and removed the resistor.

Also take a look at these 2 items

EnviroMax Plus is a Revolutionary Money Saving Fuel Catalyst. Save on Gas. Up to 35% better Mileage. Increase Horsepower. Reduce Emissions by up to 80%.

*Fuelstar* enables leaded and premium unleaded petrol engines to run perfectly on regular grade unleaded petrol without:
· Loss of power
· Valve seat recession
· Pinging and detonation
· Spark plug fouling
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Old 08-24-2005, 12:31 AM
Registered User
Join Date: Jun 2005
Location: Hopkinsville, Ky
Posts: 107
Question what about the wires?

what about my ignition wires. the plugs that were in it before were bosch platinum? i didnt replace the wires. would that make a difference? the problem was worse before but changing the plugs, distributor motor, and using electric tune up grease got it this far.
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Old 08-24-2005, 04:12 PM
Registered User
Join Date: Jun 2005
Location: Hopkinsville, Ky
Posts: 107

would turning that little screw on the back of the eha valve make a difference and if so, which way do i turn it?
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Old 08-24-2005, 05:54 PM
Machine man
Join Date: Jul 2005
Location: Friendswood Texas
Posts: 32
wire check. CHECK OVP!

Check the fuse In the Ovp. This will cause the same symptom.

You can check your wires with a ohm meter. I do not know what the resistance should be and I will check my old ones and my new ones to see if there is any difference. The other way to check your wires is simply open the hood start the car and look at the wires at night time, in as dark of a setting as you can get. Preferably in the garage with the lights off with the garage door slightly open to let the fumes out. DON'T run for too long you don't want to get dizzy or passout from the fumes nor do you want the significant other to call the loony bin to come and take you away!

Examine the wires closely for arcing. If you see a blue arc anywhere around the wires you should replace.

(from Benz Repair World)
I smell gas in the morning under the hood…
The first place we used to look on all vehicles equipped with Bosch KE injection is the E.H.A. valve. BTW - that stands for electro hydraulic actuator. The E.H.A. valve is located on the side of the fuel distributor.

First remove the air cleaner assembly. After the air cleaner assembly is removed you will be able to see the fuel distributor. The Mercedes fuel distributor is the size of a Big Mac with a bunch of steel fuel lines coming out of the top of it. On the side of the Mercedes fuel distributor you will see a small black rectangular part, held in by 2 screws, with an electrical connector. That small black rectangular piece is the E.H.A. valve. The valve leaks not the O rings behind it. The valve cannot be repaired and must be replaced.

Also make sure you check every fuel line coming to and from the Mercedes fuel distributor to make sure there are no leaks. You must be extremely careful to take precautions when working with gasoline. Check your Mercedes service manual for the proper procedures for your chassis and Mercedes engine.

(from BenzRepair 8-2004) in this forum
EHA adjustment on older engines
Normal differential pressure on KE-jet engines w/ EHA is .4 bar (5.8PSI); adjusting it slightly higher (.45 bar/ 6.5PSI) will allow for fuel distriburor wear on high-mileage vehicles. I have found that your first time adjusting should be 1/4 turn clockwise; proper adjustment will almost always be right on or within 1/16 will likely have to readjust the CO mix to compensate.

This link should tell you everything you need to know Adjusting an EHA. It IS possible!!

Last edited by cnctony; 08-24-2005 at 06:10 PM.
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