So I'll start with some background information...the car has been having issues with running for about 20 minutes alright and then shutting down. So i went through the car and replaced the cap and rotor with oem bosch parts and replaced the seal behind the adapter, after putting everything back together the car ran like new! It then ran for about 30 minutes and died...Now it has no, and i mean zero spark! I went through and double checked the cap and rotor and they look great, checked the resistance of the crank position sensor(looks good), and now im testing the coil and the resistance is good but i have zero voltage when the key is in the on position but when i crank it it jumps to 3 volts, so I switched the coil out with another 300TE that I have and no difference. Finally I tried jumping the larger terminal of the coil (10mm) with a wire running from the battery still no difference. I'm kind of stuck any help would be appreciated!

 

Nobody really wants to help?

 

Hello w210e55amg,

Don't lose hope too quickly, there are plenty of folks looking to help out when they can.

I'm going to assume you have the M103 6 cylinder gasoline engine which is the same in all 300E, 190E 2.6, 260E, 300SE, and of course, 300TEs.

I recently had a 1990 300E. with spark outside of the combustion chamber, have a no start situation where the ignition coil was corroded and gave the ignition system extra resistance that couldn't ignite the fuel in the engine.

I would recommended checking the condition of the ignition coil first. If you have access to a known good one out of another car with a M104 (2.6, 2.8 or 3.0, it doesn't matter), you can swap them and see if that solves your problem. If so, either try cleaning the old one out or go buy a new one.

Do that and we will see what you come up with.

I look forward to hearing about your progress,

-201Freak

 

thanks for the reply! and yes you are correct on the engine size it's a straight 6 3.0L so i've already tried using a coil from another running 300te and it made no difference, i'm guessing it's the ignition control module otherwise known as the ezl might be bad, i'm going to try swapping that out with the running car and see what happens. But I do have a little confusion with the crank position sensorS? i thought the only cps was the one on the front of the engine down by the crank pulley but i was wrong. The cps that comes up when you search any decent parts site is the one mounted on the rear of the engine. do both of these sensors work in conjunction with each other? does one control ignition timing while the other is...?

thanks any help is appreciated!

 

I have never had an issue with the CPS on my 190E 2.6, having 196K on it. I have seen some people has problems with the CPS and there are ways of checking them.

If I recall correctly, there should only be one CPS near the front of the engine. You can take a multimeter and check the resistance of the sensor to see if it is bad or not. Swapping the EZL sounds like a good diagnosis too. This is really nice that you have a running 300TE to help diagnosis the problem.

I don't know exactly where to check the sensor and where the connections are, but I have seen quite a few threads around the internet outlining it. I do know that the CPS can be funky to replace and most manuals say to take it to a dealership but I'm sure someone has done it.

Swap the EZL and check the resistance of the CPS. You might have to look the CPS online.

See what that gets you and we'll talk it from there!

-201Freak

 

I really appreciate the input 201freak!

Ok so I switched out the ignition control module and still no difference I also checked the ignition switch and swapped out the ovp relay. So this is what I have completely eliminated:
ignition coil
icm(ezl)
ignition switch
ovp relay

the cps when testing the resistance from pin 7 to 31d reads 850ohms (spec is 680-1200)
now im also supposed to test the resistance from terminal 7 to the ground and it should be >(greater than)199ohms, is this the center pin and any ground (battery, etc.)?
now theres supposed to be an ezl reference sensor? that should read 750ohms
where is this ezl reference sensor?

Now my second round of questions on the mercedes troubleshooting diagram for "doesn't start(cranks ok)" goes:
1.) ignition spark test (no spark at the plugs)
2.) TD signal test, What is this?
3.) Lambda Control System Quick-Test , I'm guessing i need a special scan tool?
4.) Fuel Pump delivery test (I smell fuel after cranking)
5.) Starting system test, what exactly am I testing in the starting system?

those are in order of most likely to least likely.

Now should I be getting 12v at the coil (10mm(+) and 8mm(-) terminals) when the key is in the on position?
If I should I'm not, what signal tells the ezl to give the coil 12v, I believe thats where my problem lies. But I want to cover all my bases.

On a sidenote I'm using alldatadiy for my sources so i am aware that some information might be incorrect because they might have used a generic description for some parts that might not even exist on my vehicle.

Any input is helpful!

Thanks

 

-w210e55amg

Stupid question: did you check all fuses?

I'm starting to run out of ideas of what can be cause this no spark issue.

You may have luck with that EZL reference sensor but I would not know anything about that. I've seen some Ford trucks have and issuse where there was a reference signal that was not getting to the ignition computer, causing no spark.

Otherwise, I'm out of ideas for now, best of luck to you.

-201Freak

 

Thanks for the reply!

And all the fuses in the fuse block have nothing to do with spark as far as I know it's simply the fuse, or fuses on the ovp, Maybe you can correct me. And I'm confused if maybe the reference sensor is the crank position sensor? And I'm guessing that the EZL directs 12volts to the coil when the engine is cranking, I'm not positive but seeing how the voltage goes from 0 volts and then when cranking it jumps to 3 volts. I'm going to do some more research and then probably switch out the cps and see what happens.

 

One more thing: is there spark to the distributor? This will tell if the coil itself is producing spark. You can check this by cheaking the coil lead that goes into the distributor.

There is a small chance that the new distributor might have a bad lead or something that doesn't get spark to the plugs.

If there is still no spark, you could consult a specialty German auto shop (not a dealership, this cars are ancient to them) and they might have some info if they ever had a problem like that.

Good Luck!

-201Freak

 

Finally got a good day and break from school to look at the car, So hopefully someone who has a decent wiring diagram and some deeper knowledge of the ignition system could just direct me to what seems off,

So re-cap
Ignition coil is good (came out of a running parts car, and resistance checks out)
Crankshaft postition sensor is good (resistance is within spec)
EZL unit is good (came out of running parts car)
OVP relay is good (came out of running parts car)

Now my issue is that I am not getting the voltage I need at the ignition coil.
-So moving forward with my troubleshooting, this is what is coming off of the ignition coil and what the readings are:

Terminal 15 (+)
-red thin gauge wire that runs to the ezl unit wire is in good shape and there is no resistance when i check the coil end and when I check the ezl end, so its a solid wire. But whether the car is on or not I can't get it to show any voltage when I touch the positive side of my volt meter to this wire and the negative to the negative battery terminal. I'm guessing this is a "sensing" wire for the ezl.

-Thick Pack of two wires larger gauge one is mainly white with a red stripe and the other is mainly red with a white stripe, when the ignition is on If I touch the positive end to this group of wires and the negative end to the negative battery terminal I get great voltage!

Terminal 1 (-)

-black thin gauge wire runs along side the thin red one to the ezl unit I'm also guessing this is a "sensing" wire for the ezl. it has no resistance testing from the coil end to the ezl connector so it is a solid wire, but I can't get any voltage when i touch the positive side to the positive battery terminal to the and the negative side to this individual wire.

-Thick green wire runs with the thick pack of two positive wires. I belive this is where my problem lies, I have no voltage when the vehicle is on and the positive end of the volt meter is on the battery and the negative end is on this individual wire. I'm guessing the wire may have burned out or has become disconnected, either way I need to find the other end of this wire and I would rather not rip apart a whole bunch of stuff to trace it to the other end, if anyone has a decent wiring diagram and just tell me where this wire goes to and/or what pin it is, if its on a connector.

Thanks!

 

Any help would be appreciated, maybe someone could just take a reading from their coil on a good running car with the key in the on position and tell me what the voltage is, that would help me confirm that it definitely is a wiring issue or a coil problem!

Thanks

 

Hello again!

Can you confirm that there is spark to the distributor? I know there is a lot of good parts behind it but I have seen cases that the distributor itself, even with a new cap and rotor, can kind of fall apart and not get spark to the plugs.

-201Freak

 

You mention the thick green wire. Are you referring to the one with the cap like plug that plugs into the EZL? If so, that is the CPS which terminates at the back of the engine below the oil filter.