What you describe is to me an external leak. The fuel should pass through the fuel dist and into the injectors without leaving raw fuel anywhere else. If you were to lift the fuel distributor from the airflow meter there should be no fuel dropping from it.

One could test this by removing the dist and leaving the feed and return lines coupled to it. I would plug the injector lines to keep fuel running out the outlets from obscuring the test.

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

This is what the lower half of the ditributor looked like when I inspected it earlier. It was wet from fuel.

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It seems the interest on this one has cooled, so I'll pull the distributor and try to replace the seal myself. (Fools rush in where Angels fear to tread) What have I got to lose?? It's isn't driveable like it is.

Stever, you are my hero

I fixed it just like you said to do. I warmed up the car and had a multimeter hooked up to the EHA current. Sure enough it started dropping to 0 slowly but right away since the computer was correcting the mixture. When I unpluged the 02 Sensor the current right away jumped up to 8ma, plug it back in, it fell to 0.

So I left the 02 sensor pluged in since it was obviously doing it's job and very slowly turned the mixture adjustment screw ccw, gave it some gas held it in place, relesed, and I could see the current slowly rising, but I had to make about half a turn before I started seeing the current go up. Eventually I had it at 8ma where it should be, the engine hummed perfectly, the 02 showed .5-.6 Volts, which is a bit low, so I might have emission problems, and I accidentally killed the engine when I pushed the 3mm allen key in a bit too hard, too much fuel drowned it. When I had it at 8ma right on, the engine would not start, so I had to turn the mixture screw back just a tiny bit. Now it runs like a dream, NO Hesitation, no Missing (so far, I just did this yesterday morning and drove it twice for a few minutes) and hopefully the fuel economy will jump up too.

I will make a seperate post for this just in case someone might find it uself to fix their problem.

I also put the right spark plugs, new distributor cap and rotor arm to finish off the repair, next fill up I'm adding some fuel system cleaner to get rid off all the deposits left after it's been running rich.

Once again, Thanx a million Steve, if I ever get a chance I'd love to thank you in person.

XP

Hi Cap'n Carageous and all...

I was just wondering of your 300E was running good yet, because it seems that I am having the exact same problems that you have had or are still having. Fuel build-up below throttle valve, so much that it will not crank, so I have to remove the new spark plugs and dry them, then it will crank and flood again, only to die and do the same process over again.

I have tested many components, and have new parts as well...cap, rotor, plugs, wires, fuel, filter, rebuilt head....let me think some more...lol...

Basically I thought I was getting a good deal on a blown head gasket 300E, but now I'm not so sure why God chose me to save this car from the junkyard (crusher actually ).....but as we know, God works in very mysterious ways ....so I won't complain.

New tires and chrome rims make it a great looking car to come home to, even though I can not drive it out of the yard...even to get the new tires (0 miles) out of the same spot that they have been sitting in for over three weeks! I got Cooper 225/55R16 tires, with aftermarket Benz chrome rims. Maybe I could get the engine running right and sell the engine & trans, then transplant an engine of choice...a 1970 340 Dodge engine (nickname "Baby Hemi)....parts would be very reasonable and I would increase my horsepower under the hood! LOL! I would then rename it to a 340E!!

What do you think? Also, I have wanted to conduct a poll to ask viewers if they would be interested in modifying their Mercedes to outfit it with an American made V-8 drivetrain.....what's your thoughts on this? I also want to start a 300E car club, for 86 to 91 (no 4matics)...

Looking forward to your reply and thoughts.

Attachment: My next preference of transportation....non-Mercedes and very unconventional!

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My 300e continues to confound me. Like you I am considering an American drivetrain in mine but haven't had the time to do it yet. I would like to remove the name "Bosch" from my car since the components are unreliable and cost ten times what they're worth. I'm hoping that one day I can install a Ford drivetrain and fuel management system and have a great looking reliable car.
I'm not a MOPAR fan but if you can pull it off, then you have MY admiration!!

PS. As far as saving our cars from the 'crusher', I may be doing my car a disservice!! I think it would make a great toaster!!

I know your pain you feel with your 300E...mine is loading up, possibly the seal under the fuel dist. (not o-ring, but leaking seal). On cold start (attempts that is - lets not get happy here thing this thing would crank ) it will almost sound like cranking, then simply spins over. When the spark plugs are removed and cleaned & dried, it will crank again, but only if I dry the plugs, and spin the engine over while the plugs are removed. My air flow meter chamber is wet also...too wet...too much fuel, fouling the plugs.

This process is getting old....disconnected O2 sensor did no change...EHA disconnected no change, adjusted air flow meter plate, no change. Like Steve said earlier, it is getting too much fuel. I will be looking into it tommorow, after buying plugs to plug off the injectors and pressure test the fuel dist. for leaks on the underside (with 7 & 8 pins shorted in the fuel pump relay plug).

I just bought a cool domain name pertaining to fixing your Mercedes.....it's http://www.fixmymercedes.com and it will be up & running soon ....within a few days....maybe I'll post photos and technical data concerning the issues I have had with my 300E!

Top of the day to ya!

WOW, I see you revived this old thread. Good info in here.
I tried contacting you before, no response, I am in Clayton, NC.
If you need a helping hand let me know.

__________________
1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
609 Certified

I forget which thread it was, but I posted that my car attempted to use all the gas in world! I replaced the fuel pressure regulator, all six injectors and even the ENTIRE fuel distributor/airhorn assembly to no avail. Only after gutting the catalytic convertors did it return to respectable fuel mileage.

Hi Cap'n!

I am currently also confused with my EHA readings and just discovered this interesting threat.

At the point were Steve lost you I am still lost. Steve says: "Hook your volt meter to the O2 sensor lead (leave it disconnected from the controller). If you get 1v the system is rich (or the sensor is lieing). Use the 12v thru Cap'n method to lean it out. Does the method make the engine run poorer? Does the voltage drop below 1v?"

What did you do exactly? I understand that I disconnect the O2 sensor and that I measure the voltage with the engine running. But with the sensor disconnected, how do lean out the mixture? I thought if you use the 12v thru cap'n method you are applying a >1v signal, so how could it drop below 1v?

And just to be sure: In the steps before when you grounded the signal or when you 12v-thru-cap'ned it, you had the sensor connected, right?

Final question: Did you switch off the engine + ignition to dis/reconnect the O2 sensor. I am always a bit afraid to (un)plug connectors whith ignition on.

Cheers
Tom

I just had a look at the wiring plan and finally I got the point. So forget about question 1.

But I would be still interested in the other 2

Tom

THANKS Cap'n. for this interesting review.

I wish all the best for your an your family in the new year 2004.

Cap'n I have problems yet with the idle in my 190E. Please read my threadid dated 12/ 18/ 2003.



Mario Farias
laprefar@cantv.net

__________________
MB LOVER

I am not sure which question is one or two but let me rephrase the concept for the record.

It is wise to not unplug connectors with circuits in operation, but it is no problem with an O2 sensor SIGNAL. I yelled that because the other two wires in some sensor connectors are heater circuit wires that carry 1-2 amps and souldn't be disconnected when powered. The 300e has separate connectors for the heater circuit and the signal wire (green) can be disconnected while running although it isn't necessary.

The lambda fuel correction circuit manages "closed loop" control. Closed loop is a control concept used for many systems but in this case what it means is that an exact mixture is maintained by monitoring the results and continually correcting. When the mix deviates rich the voltage of the sensor (the sensor is a power generator) goes high (above .45v). The system sees this and changes the EHA to lean out the mix. The sensor then goes low in voltage (less than .45v) and the EHA current is dropped to lean out the mix. All of this takes time so the actual voltage goes to .8 mabe .9 before turning around at the rich end or .2 to .1v on the lean end. This all happens more than once a second in a warmed good running system. Going down the road it probably happens a couple times a second or more (the hotter the sensor the quicker its readings change).

So, as diagnosticians we wish to see whether the controller can do the EHA control necessary for closed loop control. We will probably be doing this to a system that is not in closed loop control. The range of control at the EHA is about -12ma to +12ma (from lambda control). In reality this is not quite enough to take a car from running badly rich to running badly lean. (THIS IS IMPORTANT to realize). It is enough usually to take a smooth running engine to roughness in both directions, but it may only be enough for one direction. This is because the engine will run fine in a mixture range defined in percent CO exhaust gas of from about .5%CO to about 6% CO. Lambda control keeps it to .1%CO to 1% CO. So if you send the maximum lean correction to a car runnning 6% it may only take it to 1.5% and the car still runs great. On the other hand a car at 5% sent rich will go off badly at over 6%.

So now we have the O2 sensor disconnected. If we attach a voltmeter to it, the range of voltage possible will be 0 - 1v. This gives us good evaluation of mixture in the 0-1% CO range. It gives no idea about the 1-6%CO range in which a car will run fine.

If we monitor the sensor (while disconnected) and apply our own fictitious values to the open lead that goes to the controller we will initiate lambda control reguardless of actual mixture.

It is easy to apply 0v by grounding the lead. It is a little more complicated to creat the 1v signal but the 12v through the Cap'n method does good except you may have to replace the Cap'n with your own body as he is busy. By putting one hand on battery + and holding the green sensor to controller lead in the other hand the necessary voltage is transfered to the controller to imitate a rich signal. If one has an exhaust gas analyzer one can see the full range of correction that can take place with these maximum value inputs. This gives a view to the capability of control.

A properly set up mechanical portion of the KE system will have a mixture that can be read on the open circuited sensor. Some early systems suggested adjusting mixture with the voltage from the disconnected sensor. The mixture was set to .5-1.0v. Then the sensor was reconnected and closed loop had no problem because its capabilities could handle that base setting.

During the range observation (explained above) one should be able to get a view of this proper voltage range somewhere during the lean correction. That is the 12v through the Cap'n connection. Controller sees over 1v, interpretes a rich mix and rather slowly changes the EHA to -12ma eventually ...it takes a while .. maybe15-20sec (I'm guessing I have never timed it).

If the car was actually lean when this process starts the engine will probably die. Most often the mix is rich and so far above 1% CO that full -12ma may only get the system down into the less than 1%CO range necessary.

These are the views you can get. Getting meaningfull answers will require aquiring realistic experience of these happenings so that conclusions can be formed.

The thought of replacing this exquisite Bosch system with anything domestic blows my mind. This simple gourgeous system replaced with a crude, undiagnosible, carburator....there is real progress...not!

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

Steve, you have the patience of a saint. I already pointed this question to the cap'n, so you don't have to explain the same thing over and over again.

Today, I made a strange observation again. You might remember my problem from the thread AFM pot. I made a little mistake there when I sad that EHA receiceves a current of 0 to -8mA which is 8mA when the engine sounds loaded. This should have been -8mA.

Anyways, last time I measured KonEoff a stable 10mA for the first 10s then switching to a stable 20mA (19mA). This happened again today. However, as always I forgot to memorize the polarization before starting the engine and hence turned off the engine again. When I immediately turned on the ignition, I saw the 10mA for 10s again. However, then the current didn't move forward to 20mA but to -7.5mA. I started the engine, turned it off, turned on the ignition: again a stable -7.5mA after approx 10s. What has happened? And is it common that I have these 10mA first?

My other readings were:
Computer side of O2 connection grounded: 10.5mA EHA
Computer side of O2 connection Cap'ned: -15mA EHA

Computer side of O2 connection grounded: 0.95V O2 sensor
Computer side of O2 connection Cap'ned: 0.02V O2 sensor

To my understanding this proposes a working O2 sensor, a capability to control and a mixture that is not too far off to be controlled. Though I am wondering about the asymetric EHA control capability (-15 to 10mA).

My primary problem was the EHA current fluctuating between 0 and -8mA. I assume that the -7.5mA problem started today, as it never happened during my 2 measurements before. As the parts I tested today seem to work, I would assume the problem to be either fuel pressure (differential pressure in AFM, system pressure), a wrong mixture that is hard to control or something I don't know. Would you agree that if the sparks, the injection valves or the idle valve would be the problem, the rough idle would occur also with EHA off?

Unfortunately I don't have the equipment to measure those pressures. Is there anything else I can do to narrow down the problem?

I really appreciate all the time you spend to answer our questions. For me it is also very interesting to follow your logic to search the origin of such a problem. I do have an engineering background, but as you know, the gap between theory and practice is in practice far larger than in theory. And with this car (W107 SL) I am very interested to learn what is happening behind the curtain.

Thanx a lot
Tom

Does anyone know what pin #3 at the service connection should read with ignition on and a fully charged battery? Battery voltage is at 12.41 with radio playing, at 65 degrees.

My readings at service connection:
Pin #1>11.48 volts
Pin #2> 0.00 volts
Pin #3> 3.76 volts >>seems low from what I've read in other posts...
Pin #4> 12.33 volts
Pin #5> 12.33 volts
Pin #6> 12.37 volts

Readings at TDC (crank) sensor plug: 794 ohms

Voltage reading at EHA plug (disconnected)> 4.14 volts

Fuel Pump Relay:
Pin # 1> 2.18 volts
Pin # 8> 12.40 volts
Pin # 9> 12.31 volts
Pin # 10> 11.47 volts

When the fuel dist. was checked under pressure, it was damp, and wet each time when depressed by thumb. Actually the stem/seal fit is loose...very loose, where the stem travels through the adjustment/locking cap. Maybe someone rearranged this fuel dist. before I purchased the automobile?.....the locking washer showed evidence. If I need another fuel dist. for parts (to obtain correct fitting to the stem locking cap), would someone have a bad fuel dist. for parts? Will make more tests tomorrow and post them here. Thanks for everyone sharing info, especially to Steve
!

__________________
'87 300E | 2.6 engine
Artic White - Navy blue interior, chrome rims, very clean and sharp!
91 300E
89 300E


The rest of my collection are just cars and trucks...no more "automobiles"...