[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.

 

[isthenew]

To me, this screams bad EHA. Is it leaking?

That said, it could be anywhere in the KE-jetronic system. And if the EHA isn't leaking, start elsewhere. Bad OVP. Bad fuel injectors. Mis-adjusted 3mm tower or air flow plate. Bad air flow potentiometer.

 

[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?

 

[isthenew]

The EHA will be leaking gasoline out of its weep holes. This is a picture of mine.

Here's a pdf on the KE-jet tonic system. You'll want to study up on it.

 

[isthenew]

Your best bet is to search the w124 forum. They have a lot more information on the m103 (and m104) engine(s).

 

[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

 

[UncleWolfy]

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

 

[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.

 

[UncleWolfy]

Almost forgot, you mentioned it won't engage into a gear, but it does move slowly?! Try reverse, 4/3/2/1 maybe your torque converter is toast or low on transmission fluid and no matter what you do to the engine the car doesn't get the torque onto the rear axle. Idle the car and check the transmission fluid level when it is warm. It should be between the two markers. If it is too low, your car might not want to drive. If you need tranny fluid, go to Autozone and get Valvoline MaxLife full syn ATF (DexronVI, Mercon LV, DEX/MERC in a red bottle/red fluid). On the back it says Mercedes-Benz NAG-1 compatible. That fluid works well for our older 722.4 or 722.5 transmissions.

 

[Momo08]

It does engage into gears it just doesn’t pick up speed. It turns off before it changes gears.

 

[Momo08]

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

S

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

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.

This is what I got apologies it was a bit dirty when I took the picture

 

[UncleWolfy]

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.

 

[UncleWolfy]

Here is what I found about the trim plug. Car should still be running without it, but you never know.

Here is the official MB guide as to what EZL trim plugs to use for specific conditions.

Version	Fuel RON	Trim Plug Connector part number*	Resistance (ohms/kohms)	Ignition timing correction (crank angle w/o vacuum)	Number on plug
CAT	Premium 95	015 545 67 28	2.4 kohms	0	2
Without CAT	Premium 95	015 545 71 28	220 ohms	0	6
CAT	Regular 91	015 545 68 28$	1.3 kohms	-3	3
CAT	Regular 91	015 545 69 [email protected]	750 ohms	-6	4
Without CAT	Regular 91	015 545 70 28	470 ohms	-4

* If no adjustment coupling is available, the injection timing at full load is retarded by approx 3 degrees crank angle.
$ With frequent regular fuel operation
@ With pinging complaint using regular fuel

 

[Momo08]

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

Ok, so can I get a resistor or do I need to get a whole new ezl?

 

[rayhennig]

Ok, so can I get a resistor or do I need to get a whole new ezl?

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

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

 

[Bill SD]

Another thing to check, is the OVP relay...a failing one the car will run but poorly and exhibit other symtoms

OVP Relay: what does it do, exactly?

Sorry for visiting a topic that seems to have already gotten a lot of airtime, but even after digging through many forum threads, I cannot find a definitive description on what the OVP relay does and why Benz owners are always suspecting them as THE culprit for many engine woes, and subsequently...

www.benzworld.org

 

[Momo08]

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

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

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?

 

[rayhennig]

I wonder if that actual clear slim tube might need to be connected somewhere important?

A vacuum tube from the inlet manifold is connected to here:

R

 

[Momo08]

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.

Ok, so I went out in the rain here in sunny souther Cali, and this is what I found.

my question would be, do I just replace the green little O-rings, or would I need to replace the whole unit?

 

[isthenew]

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.