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Please help! 300e 24v M104.980 won't start or starts and stalls

51K views 374 replies 17 participants last post by  Gerson C. Grossl Jr. 
#1 ·
Hi, i'm new to this forum ,
I have a serious problem with my 300e 24v , I have fuel and spark but won't start. i read the codes and gave me code 17 on port 8 (crankshaft position sensor) i replaced my cps and still no start :( I also replaced camshaft position sensor and nothing. dont know what to do, how can i test the EZL ? but if that was the culprit shouldnt it give me the code on code reader?
 
#2 ·
Sounds like dying EZL, which that particular engine is known for without exception. It happens to every single one.

There is no real way of testing the EZL, although I would recommend removing your unit, remove the white thermal grease compound (on both the EZL and vehicle body), and reapply a fresh layer of computer grade thermal grease

Other than that, start looking for a replacement EZL although find a functional one at a reasonable price is going to be a challenge as they are in very short supply

BTW, which brand and model spark plugs are you using? Using the wrong ignition components can mess with the ignition system and possibly even kill the EZL
 
#4 ·
Let's back up a bit here. First off, welcome to Benzworld and the W124 forum Gerson. You say you have spark and fuel. What have you done to verify spark? When did the problem begin? How many miles on the car and other than the items noted, what sort of service history does the car have?

Feed us more information and we'll be able to get you heading in the right direction.

Welcome

Jayare
 
#5 ·
Thank you Jayare , Verifying spark i just put a spark plug in the spark plug wire outside the engine and asked someone to crank engine for me. i could see a spark coming out from wire, i did that to all 6 wires one by one. as for verifying the fuel i removed all injectors and jump started fuel pumps, look my video here when i was testing the fuel injectors ( ) I got this car with this problem already. previous owner said the car was running fine until 4 months ago when this problem suddenly occurred after he parked the car in his garage then the next day the car simply doesn't want to start anymore or when it does it will die right away. car now has 195,075km (around 121,000 miles) it's a 1992 300e 24v . ex owner didnt have receipt for services made but After i got the car i have replaced spark plugs/ dist. cap/ rotor/ crankshaft pos. sensor and camshaft pos. sensor, also i put fresh gas in tank.
 
#6 ·
You imply that it sometimes does start and/or that you have a spark. In that case, your EZL is working. In my experience, they either work or not.

Certainly, replace the heatsink compound under the EZL to ensure perfect thermal contact with the metal underneath.

Now start with the simple things. Make sure your HT is in first class order with original quality parts and scrupulously clean and dry. Check the distributor carefully.

Check you are getting a good spark.

The fuel system must be the next suspect. I've not had any trouble here so I'm not an expert but try tipping a bit of clean fuel down past the airflow meter on to the butterfly valve. Try starting the engine.

Does it fire?

My motto is to be optimistic and not assume that expensive components are dead. The 300-24 system is pretty reliable if its well looked after with the EZL also being pretty reliable in my experience. Naturally, the EZL may suffer in very hot conditions if it cannot dissipate heat.

My rule has always been to check and ensure absolute cleanliness of all electrical connections. Unplug everything on-by-one and apply a good quality contact cleaner to thoroughly clean all contacts. Do this also to all electronic module connectors.

Good hunting and keep us updated with progress.

RayH
 
#10 ·
hi everyone, i tried to jump start and still nothing. only crank and sometimes starts and stalls immediately, this eliminates MAS as a culprit ? i also put a new heatsink under ezl as i noticed it was very old and just a little bit then i checked spark again i saw it had a good spark coming out. so this eliminates Ezl ?
 
#12 ·
The MAS can drop out during cranking. Ie; just because the pumps sometimes run does not mean the MAS is in 100% working condition. If you want to test for a faulty MAS –remove the MAS module and jumper the fuel pump pins in the multiplug. The pumps will run continuous when jumpered. If the car starts and runs fine with with the pumps jumpered like this then that confirms a faulty MAS module.

Regarding the EZL- my experience of them failing is they go dead. No spark at all. If you car is firing sparks to the spark plug wires then the EZL is likely fine. Proceed with the MAS test above first & foremost.

If the car sometimes fires up then it seems your problem is fuel supply related – not dead ignition system. You have said you are getting good spark at the spark plugs so the Ignition system is not suspect for your no start situation IMO.
 
#13 ·
sorry i wasnt clear when i said i jump start i did exactly like you said i removed MAS and jump started fuel pumps and car still doesnt start. i did spark test from coil wire to dist cap and i also got spark. i starting to think it's fuel related problem.. or ECU maybe? Is there any possibility to be the ECU ?

now i'm swapping the fuel distributor for the original one that came with the car but due to it was leaking fuel when i got the car i just changed it for another FD i had at home from a w124 M103 i had before. i will need to replace the gasket for the good one.
 
#14 · (Edited)
I've never really had problems with a fuel distributer before so maybe someone else can assist with that.

If the fuel pumps are running constant with a audible buzz then it sure should be getting fuel.

A ******* test to diagnose a fuel starvation problem is to spray a little 'easy start' or similar ether product into the intake & crank it. If it fires right up for a few seconds every time you spray a little ether then it's a confirmed fuel fault.

Also if you haven't already done so do make sure all fuses are replaced with copper ceramic ones. It could be an electrical fault still which might have a knock on effect on the injection. Like a immobiliser fault or ignition tumbler.
 
#15 · (Edited)
In order to help you with the best suggestions, let us know everything you've changed out. I have a correct M104.98 FD at home. I'll be returning to FL in another 10 days or so. In the meantime, replace all fuel related parts you've changed out. Then, with a can of starting fluid in your hands, spray some into the intake and crank the car. If it fires off, then it is a plain and simple fuel issue.
 
#16 ·
yes fuel pumps are running constant and with a buzz, i had replaced the fuses and cleaned the area when i got the car.

things i have changed: camshaft pos. sensor , crankshaft pos. sensor, fuses, dist cap., rotor, spark plugs, and swapped the original fuel distributor for a good one with new gasket from a M103 w124...

I have done this spray test before but still starts and dies. but going to do this test again tomorrow.

i still wonder , could this be ECU problem ?
Thank you.
 
#18 ·
These things start without most of the engine electronics, except the EZL that you've verified.

It fires but won't continue. True?

I would be thinking about the air metering flap. Is it moving smoothly and does it settle to the right place. I'm not expert here but I recall that the flap can defeat the running of the engine.

Sorry, I'm working right now so better get back to that!!!!

R
 
#17 ·
I understand what your saying. What I'm trying to convey is keeping the car running by shooting quick burst of starting fluid before the initial firing dies off. Just outboard of the FD is a metal tower about 2" tall. It should have a metal ball on the top if it hasn't been tampered with (anti tamper ball). Is the ball in place or has it been removed?
 
#20 ·
no , the car doesnt have that anti temper ball anymore. i couldn't make that spray test today. i was fixing the car's original fuel distributor to put it back in then after finish i removed the working one i had in the car and installed the original and jump start to check if worked. it doesnt. i tried many times with different tower position still nothing. then i thought.. OK give up just put it back the working one.. but when i jump start strangely even the working one now doesnt work anymore ?? WTF i didnt disassembly it why not working anymore. after spent many hours in that all i gave up. maybe the problem is now on the meter plate. :( so frustrating.

yes it fires but wont continues, yes metering flap is moving very smoothly but i dont know if it's settle to the right place. how can i check that?
 
#22 ·
... i tried many times with different tower position still nothing. ...
Am I right assuming that you mean you changed the Lambda control (duty cycle) adjustment many times?

While checking it is one of the standard diagnostic measures and too often neglected, changing it is too often done too easily, IMHO.

Anyway, if you did change it:
1) Which duty cycle did you see at idle (warm engine) before you changed it the first time?
2) To which duty cycle did you change it (with the warm engine at idle)?
3) Which duty cycle did it show after that at 2500 rpm?
4) Which duty cycle do you see:
- with ignition switched on (engine not running)?
- and air sensor plate manually deflected?
- and with air sensor plate in rest position and throttle manually fully opened?


I’ll apologize if it turns out that this specific suspicion between my lines is unjustied. :wink_2:

H.D.
 
#23 ·
Gerson,

First off, complete your profile so we'll know where you're located. It makes a big difference. Secondly, are you saying you've disassembled the FD itself (not just removing it) and you've been turning the adjustment screw inside the metal tower?
 
#25 ·
hi sorry i was out it's been a busy sunday. Im located in south side brazil (i apologize for english mistakes)

yes i mess up with the lambda adjustment already, and i dont have a tool to measure duty cycle i only have a common voltmeter

when i said i tried different tower positions i was meaning the tower inside the fuel distributor i tried all the 6 possible positions but none of them makes the FD works again. when i jump start and press the air meter flap no gas is coming out of the fd anymore :(

thanks alot for the pdf gonna try resseting it.
 
#26 ·
Anyway, if you did change it:
1) Which duty cycle did you see at idle (warm engine) before you changed it the first time?
2) To which duty cycle did you change it (with the warm engine at idle)?
3) Which duty cycle did it show after that at 2500 rpm?
4) Which duty cycle do you see:
- with ignition switched on (engine not running)?
- and air sensor plate manually deflected?
- and with air sensor plate in rest position and throttle manually fully opened?


I’ll apologize if it turns out that this specific suspicion between my lines is unjustied.

Saw your questions now. i got the car like this already so im trying to fix by myself for around 1 month already but couldnt make it yet. so i dont know about duty cycle if it was adjusted already or not maybe it was and now messed up :(
 
#27 ·
kinda lost haha i saw more question on previous posts . yes i had disassembled fd but not the one that was working fine in the car. i disassembly another one (original one that came with the car) to try to fix it changing gasket inside but it did not work. and very strangely the one that worked fine and i did not disassembled that also didnt not work anymore !? really could not understand why. maybe because i mess up with the lambda adjustments?
 
#28 · (Edited)
You will be able to measure the duty cycle by using a common volt meter. In our DIY sticky is a thread "fuel mixture adjustment" that has the formula to use to convert volts to duty cycle. Use that, and H.D.'s instructions and you should be able to get the car running.

I'd suggest re-installing the working FD and not make any adjustments until you fully understand what you're doing.

Jayare
 
#29 ·
Okay Gerson,
I (almost) get the whole picture of what you have done … but I don’t want to ask you about further details … it’s too scary … lol

I give you some suggestions now about how to ‘reanimate’ your KE-Jetronic, but I want to remind you that following them only makes sense if done precisely ... and when people from where I live say “precisely”, they mean it … lol

Step 1)
Check the air sensor plate’s zero position according to the pdf I posted. And while you’re at it, check if the air sensor plate is centered in its housing - the gap between the plate and the housing should be homogeneous all around. If both is okay, don’t further touch the air sensor plate.

Step 2)
This step is the actual KE-Jetronic reset. That’s a basic hydraulic calibration of the FD, of course, in this case of the one which was not disassembled. I suggest to do the reset like this:

  • Put an absorbant rag around the FD, and loosen one of the injector pipe fittings on top of the FD.
  • Let the fuel pump(s) run by connecting them to 12 V, for instance via jumper wire in the MAS socket.
  • Let the spring loaded adjustment pin in the adjustment tower between the air sensor plate and the FD snap into the adjustment screw by pushing it carefully down and turning it a little to and fro with the Allen key. Don’t put too much force onto the key, so that there is no downward force on the actual adjustment srew, otherwise the reset wouldn’t work (properly).
  • If fuel is coming out of the port with the loosened injector pipe, turn the Allen key counterclockwise until no more fuel comes out, plus half a turn.
    As an alternative to loosening one injector pipe to see whether fuel comes out or not, you can also listen close to the injectors and try to hear whether they spray or not. But I think for a first-timer the loosened injector pipe fitting is the better way.
  • Then slowly turn the adjustment screw clockwise until fuel just starts to come out, respectively you can hear the injectors start to spray.
  • Then turn the adjustment screw more than a quarter turn, but less than half a turn counterclockwise again.
  • Tighten the injector pipe fitting again.

Step 3)
Provided that there are no other inhibiting problems, you should now be able to start the engine and perform a correct Lambda control (duty cycle) adjustment.
For that I suggest rather a thread I created less than two weeks ago than the thread in the DIY sticky, which Jayare mentioned. It’s tittle is “KE-Jetronic Lambda control (duty cycle) adjustment” and you get to it via this link:

http://www.benzworld.org/forums/w12...97-ke-jetronic-lambda-control-duty-cycle.html

I listed everything you need to know at this point for the duty cycle adjustment clearly and in detail up from the chapter “Purpose of the adjustment“ in post 2.


I’ll be a little short of time in the next couple of days. If there are questions about further details like “how do I get the fuel pumps to run via jumper wire”, etc., I’m sure there are other friendly members who can help you.

And please don’t disassemble FD’s again. :wink

H.D.
 
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