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93 300sl starts fine but does not drive

1928 Views 52 Replies 7 Participants Last post by  rayhennig, 
Momo08
I’m not sure if I’m in the right place. I’ve looked everywhere on the internet and in your forum for similar cases to my car, and so far nothing like it. So I bough this 93 300sl not running. Looked really good and complete minus the ignition control module. I found a used module online and bought it. Connected the different sensors to it and the car turn on like clockwork. It idle a bit high but I figure that was normal since the car had not ran for a long time. The po mentioned it hadn’t ran for about a year. So I let it idle for a bit, after a few minutes I put it in drive and that’s when I noticed the car would not engage into gears. It drove super slow and as I tried to accelerate harder it would kind of just want to turn off. To the point it just turns off randomly. I’ve replaced dristributor cap, rotor, cables and some rubber hoses. Still have the same symptoms and I just don’t know where to start looking. So again, the car will start fine, idle ok, and after a few minutes will just die out randomly or if I try to put it in gear and drive off it has no power and shuts off as well. Any help or suggestions would be much appreciated. Thank you in advance.
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Momo08
Thank you for replying, so how could I check if it’s leaking? Any videos or literature on how to go about doing this work?
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Momo08
Ok I don’t remember seeing anything that wet in the engine. Then again, I was not looking for anything in particular. I’ll look it up tomorrow and come back with updates. Thanks
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Momo08
Thank you UncleWolfy, that’s definitely a lot of info and I’ll start on it as soon as weather permits it here. Will get back with updates soon.
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Momo08
It does engage into gears it just doesn’t pick up speed. It turns off before it changes gears.
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Momo08
UncleWolfy said:
Sorry to hear that! The KE Jetronic is very funny sometimes. The fact it starts is good. That probably means the EZL you got is somewhat working, but since it controls pretty much the entire ignition system, it doesn't mean it is working correctly. If you have a 1993 300SL-24V, you need to check, if you have the proper EZL.

Please take a lock and confirm your BOSCH/Siemens part number is printed on it. If you have the M104.980 or M104.981 engine your acceptable EZL's should be: 0075457032, 0075457132, 0105459532,0105459632, 0125452032, 0125452132. Make sure it has the round MAP controlling resistor 0155456728 plugged in.

Even if you have these installed, no guarantee it is a working one, other than you have a refurbished with warranty.

Next you need to start the car, idle it and then check the On-off ratio. If that is out of range, your car will not accept power and or stumble or die. The EHA does not adjust idle mixture ratio, but acceleration fuel pressure. If that thing is wacked, it will not drive properly. There are many protocols out there that can help you measure and adjust.
How old is the fuel? Is there enough fuel pressure coming from the fuel pumps, Do both work? Do you hear them humming when the car runs.

So many ways to mess up an M104. Since the car starts, you do have compression and spark and some fuel.
Go from there.

Greetings
Click to expand...
S
UncleWolfy said:
Sorry to hear that! The KE Jetronic is very funny sometimes. The fact it starts is good. That probably means the EZL you got is somewhat working, but since it controls pretty much the entire ignition system, it doesn't mean it is working correctly. If you have a 1993 300SL-24V, you need to check, if you have the proper EZL.

Please take a lock and confirm your BOSCH/Siemens part number is printed on it. If you have the M104.980 or M104.981 engine your acceptable EZL's should be: 0075457032, 0075457132, 0105459532,0105459632, 0125452032, 0125452132. Make sure it has the round MAP controlling resistor 0155456728 plugged in.

Even if you have these installed, no guarantee it is a working one, other than you have a refurbished with warranty.

Next you need to start the car, idle it and then check the On-off ratio. If that is out of range, your car will not accept power and or stumble or die. The EHA does not adjust idle mixture ratio, but acceleration fuel pressure. If that thing is wacked, it will not drive properly. There are many protocols out there that can help you measure and adjust.
How old is the fuel? Is there enough fuel pressure coming from the fuel pumps, Do both work? Do you hear them humming when the car runs.

So many ways to mess up an M104. Since the car starts, you do have compression and spark and some fuel.
Go from there.

Greetings
Click to expand...
So after reading this, I went to check on the ignition control module and the serial number does March one of the ones you wrote up here but k just noticed it doesn’t have the resistor that you’re talking about? Or at least I can’t spot it.
Auto part Font Metal Household hardware Titanium

This is what I got apologies it was a bit dirty when I took the picture
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Momo08
UncleWolfy said:
Yes, you are missing the resistor, that maps the EZL to the car/computer. Here a picture where it is and how it looks like. It's a plug-in, you might be able to buy one on Ebay. View attachment 2800230
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Ok, so can I get a resistor or do I need to get a whole new ezl?
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Momo08
rayhennig said:
You should be able to find a resistor by Googling the part number. I guess you'll want No: 2 for premium fuel with Cat. There's one here:

1990-2002 Mercedes-Benz Adjustment Connector 015-545-67-28 | Mercedes-Benz Parts

1990-2002 Mercedes-Benz Adjustment Connector 015-545-67-28
www.mercedesbenz.parts www.mercedesbenz.parts

The car will run fine without the resistor - I can barely tell the difference.

I'll be optimistic here and say that, if the car starts, your EZL is OK. That has been my experience over 24 years with the same car - same engine as yours.

If you can find another EZL, I recommend that you put one in stock. They are increasingly difficult to find and costly - well over 1000€ in Europe and 2300€ here in rip-off France.

Also, don't forget a thin, even layer of good quality heatsink compound between the EZL and the bulkhead - nice clean surfaces too. You don't need any foil layer either.

Good luck - nice engines when they're working correctly.

RayH
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Thank you RayH I will definitely keep my eye out for one. I stupidly thought that the missing resistor slot was actually a vacuum hose, went and plugged one there that was not connected to anything. I wonder if that actual clear slim tube might need to be connected somewhere important?
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Momo08
isthenew said:
The EHA will be leaking gasoline out of its weep holes. This is a picture of mine.
View attachment 2800174

Here's a pdf on the KE-jet tonic system. You'll want to study up on it.
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Ok, so I went out in the rain here in sunny souther Cali, and this is what I found.
Hood Motor vehicle Automotive design Automotive tire Gas

my question would be, do I just replace the green little O-rings, or would I need to replace the whole unit?
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Momo08
isthenew said:
You can try and replace the o-rings. That's what I did. In my case, that didn't work. And I bought a new EHA. And I bought like 10 of those o-rings. Because you can lose them.

Oh, and if you're new to MB, I'd suggest buying the EHA from fcpeuro. They have a lifetime warranty. And my EHA which is 18 months old just tested as "bad." So I'll be sending it back using that warranty.

And everyone will say don't buy a used EHA. I tried it. Didn't work. It was bad. Bought new.
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So updating, I put new O-rings. Didn’t change much, except it is not idling as long as it was before. It starts idling really high and bouncing between 1000 and 2000 as if I was trying to rev it up but I’m not even pressing the gas pedal at all? I’ll definitely have to get the new eha, but was wondering if the symptoms meant anything?
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Momo08
The transmission fluid is not dark or black but it’s not red or pink for that matter. Now, quick question, how does the transmission play into the cars bouncy idling? And can I do a transmission fluid replace or flush before doing an overhaul? Thank you for your input btw
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Momo08
It was pretty wet when I took it apart haven’t paid much attention after I put the new O-rings. I definitely would like to test it, although I’m ready to buy a new one from tcp as you mentioned.
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Momo08
Tcp I meant to say. And do you have any links as to how to test the eha? Also, where else would I look if the eha turned up to be good or I get it replaced? Thanks
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Momo08
Ok, stupid question, where would I find the ovp in my car?
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Momo08
2
Bill SD said:
Its under the cover behind firewall on passenger side, you can test this before replacing blindly. I think there is a thread on testing it.

www.benzworld.org

OVP - basic function and test

Mercedes OVP – A Basic Primer and Test Process I am dealing with my second failed OVP and reviewing the various links prompts me to try to consolidate some of the scattered information into this single format. I hope it is useful. See Figure 1. below for a picture of a typical OVP relay...
www.benzworld.org www.benzworld.org
Click to expand...
Musical instrument Wood Plucked string instruments Jewellery Folk instrument

Automotive lighting Finger Magenta Plastic Electric blue

good afternoon everyone, so I’m a bit confused right now as to this ovp relay. One, can someone explain to me why it has 9 prongs but it only connects to 6 of them? Two, the 2 10amp fuses seemed fine and not corroded, could this ovp still be the cause of some fo the issues I’m having? Thanks for all the info everyone has been sharing by the way. I’m not a full on mechanic incline person by I’m trying and I love the car and would love to drive some time in the near future with everyone’s help
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Momo08
aam said:
More pins?
Is two relays in one.
Same part for many...
Regards,
aam.
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My mistake, yes, more pins. Actually 3 of them stay unconnected so I’m wondering if that’s actually normal
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Momo08
Good evening everyone, so things seem to have taken a turn for the worst. So after checking the ovp, and not seeing anything out of the ordinary wrong with it, I went ahead and installed the ovp back on it. At this time I go and crank the car and it won’t stay on. It starts and dies right away. I bought a new ovp, hoping maybe I messed it up some how, installed the new ovp and the car starts but dies as quickly as it turns on. I’m at a lost here. Seems I’m going backwards instead of forward trying to get this car to daily driver condition. Please help
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Momo08
No, the car used to start and stay on for a while before it just fine, before it would unexpectedly cut off. After the ovp issue, it starts and dies right away. Correct me if I’m wrong, I’ve looked for fuel pump relay location here and it shows me that there is no relay for my car. It’s points me to a box that looks more like a module. Is this the correct part? And if not, where is the fuel pump relay located on a 93 300sl? Thank you again
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Momo08
I’ll keep looking and let you know what I find. Thank you for replying btw
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Momo08
No, thank you for any bits of info. Everything helps so I don’t go in completely blind trying to fix it.
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