Hi...

My car, W124 93 320 E, 280k km, starts to shake violently once the temp reaches 85C or more. Putting the Gear in neutral has a very minimal effect on the vibrations. While vibrating, the cars acceleration drops drastically, taking almost 14 seconds to reach 80kph, but i can reach higher speeds though. If I switch off the car then on Again the problem goes but comes quickly as the car is still hot.

I took it to several repair shops and the almost unanimous decision was to replace the wiring harness. After Paying 700$ for the harness the problem still persists. Is there any proper testing procedure to try to pin down the problem, or simply replace all suspected parts (anyway the car done almost 300k)?

One of the repair shops told me before replacing the harness that the ECU (computer) might have been damaged due to bad cabling. Can this be a reason?

I really like this car a lot. I hope to find a solution here.

Thanks

Robin

It sounds like you have a mis-firing cylinder(s). It's a pretty simple diagnosis, as long as your shop has the right equipment.

"starts to shake violently once the temp reaches 85C or more."

"Water Temp Sensor" Easy DIY & cheap, also very common in many cars

Most every thing else will cause problems in all temp ranges. Of course there's always the expensive items, but try the cheap one first.

Bob

Get the codes.

Thanks for the replies,

I remember changing the water temp sensor just over a year ago, I will do that again if it will solve the problem.

If the problem is due to a misfiring cylinder, wont it occur whenever the engine is working, regardless how high the temp is? And how much wold it cost to repair?

As for the codes, can you please explain how to get them. I do not have any code panel next to the battery.

Did anyone experience vibration issues due to a faulty computer/ecu?

All help is appreciated

Thanks.

There are a lot more people that know a lot more than me on this list. In the meantime, I'll give you a few ideas until the masters like Arthur get back to you.


You wrote
I remember changing the water temp sensor just over a year ago, I will do that again if it will solve the problem.
>>>It's probably OK. It was only a quick though of mine.

If the problem is due to a misfiring cylinder, wont it occur whenever the engine is working, regardless how high the temp is? And how much wold it cost to repair?
>>>It could be just one or more spark plugs or coils or spark plug connectors. Your car has 3 coils each feeeding 2 spark plugs [only use Bosch f8dc4] This engine doesn't like platinum. Under each coil is a connector [$10 ea] that is prone to detoriate because of heat. You need a 5.5 mm allen to remove the bolts and a 10 mm socket for the 2 nuts holding the air tube. Loosen the clamps at both ends of the air tube and be careful with the MAF sensor in the pipe close to the battery. It's expensive.

As for the codes, can you please explain how to get them. I do not have any code panel next to the battery.
>>>It's about 3 by 2" located about 6" in front of the right side of battery. It has a plastic flip off cover.

Did anyone experience vibration issues due to a faulty computer/ecu?
>>>From all my readings on this list, it's rarely the computer. You don't wanna have to buy even a used one. They're rather pricy.



As Arthur said, you need to get the codes. You can get a complete diagnostic check from either a MB dealer or inde [who has the correct computer] or you can build one of Arthur's code readers that produces an anazing anount of information. You can get all the parts to build the code reader from Radio Shack for less than $10. I've attached piks of wiring schmetic and photo of my code reader. I used a 35 mm film container. Also is an illustration of the diagnostic module in your car.

You push Pin 1 to get codes from it, and use the code reader for pins 8 and 14. Do a search on "arthur dalton code reader" for more info.
Once you "read the codes" you can search and post to the list noting the pin # and code # with chassis [124] and engine [m104] and people can help you much easier.

For build specs of your car go here an enter its serial #
http://www.detali.ru/cat/oem_mb.asp

You wrote
I remember changing the water temp sensor just over a year ago, I will do that again if it will solve the problem.
It's probably OK. It was only a quick though of mine.

If the problem is due to a misfiring cylinder, wont it occur whenever the engine is working, regardless how high the temp is? And how much wold it cost to repair?
It could be just one or more spark plugs or coils or spark plug connectors. Your car has 3 coils each feeeding 2 spark plugs [only use Bosch f8dc4] This engine doesn't like platinum. Under each coil is a connector [$10 ea] that is prone to detoriate because of heat. You need a 5.5 mm allen to remove the bolts and a 10 mm socket for the 2 nuts holding the air tube. Loosen the clamps at both ends of the air tube and be careful with the MAF sensor in the pipe close to the battery. It's a expensive.

As for the codes, can you please explain how to get them. I do not have any code panel next to the battery.
It's about 3 by 2" located about 6" in front of the right side of battery. It has a plastic flip off cover.

Did anyone experience vibration issues due to a faulty computer/ecu?
From all my readings on this list, it's rarely the computer. You don't wanna have to buy even a used one. They're rather pricy.

Bob
PS I noticed your milage is in "km." Where are you located?

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It would be unheard of for the coolant temp sensor to cause any issue like this. The HFM system will substitute a nominal value for a sensor acting radically and it would take a radical action to produce a mixture capable of such. The system just wouldn't tolerate it from an adaptive point of view either.

The system recognizes misfires and shuts down the injectors on offending cylinders to protect the catalytic convertor. It does this until the key cycles. This is the reason the problem goes away briefly on the key cycle and also conclusively insolates the diagnosis to one or more single cylinder misfires. On that motor that almost always means a coil or the plug connector under the coils. Because the connectors are so fragile, cheap and hard to specifically diagnose we replace all three of them when we replace plugs. I would suggest doing such. If it isn't the solution then you likely have a coil problem. Hopefully the misfire will be identified to a particular cylinder by fault code, but I wouldn't bank on it on a 93 model.

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

SB,

The misfire will show up on pin 8 on that HFM model.., coil output also will trigger a code on the same #8 module.
As you state , most likely is coil to plug connectors misfire coupled with injectors being shut down b/c of misfire...these connectors do not get changed when they do the wire harness [ why not is beyond me ]..but I learned from you to change them out when doing plugs regardless.
I would also make sure they have not gone with Plat plugs on you . Same misfires with occur with plats on 104 HFM engines. [ possibly due to Waste Spark set-up of series plug wiring] ......Like to know your opinion on that ,SB..if you would..

T-Bell,

..here is some code info for that system
http://www.peachparts.com/shopforum/showthread.php?t=107630

Arthur,

From your own code list, there are no misfire codes. I think they only set misfire codes after 94, but I could be wrong. I'm not even sure a 93 would have a DM.
The platinum plugs are just bad everywhere. I know of no particular waste spark issue that would make them worse in such a situation. But fouling across the ceramic seems to be the problem and the waste spark could get it started, I suppose. I do know I have wasted plenty of time looking at rough idles that those plugs caused after being told the car had new plugs and not thinking plugs would be the issue. after all those cars never have plug issues unless the plugs are terribly old.

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

Thanks for the generous replies...

I took my car to the mechanic today, changed 2 fo the 3 coils ( the shop ran out of stock) but the problem persisted. He interchanged the positions of one of the new coils with the remaining old coil but again the same problem. I hope to get a third coil tomorrow and solve the issue. I will also change the coil connectors and spark plugs, and will make sure the latter are Bosch f8dc4.

I bought the car from a showroom that imports used cars from germany, so I guess it was meant for the german market.

I will update as soon as I get the car fixed

Thanks

SB,
The USA version '93 124 with 104 HFM/SFI is the first year with the DM , but only in Cal version . Same as the 94/95 E320 vintage, with the exception of the 93 came in both Federal and Ca. versions , with the Ca. version having the built-in Led/Sw and the N59 emmissions DM module. The Fed version did not have this feature, but all 94/95 USA- HFM/SFI 104s had the Cal version w/Led/Sw.
I do have info here that states this difference , but I also have another source that agrees with you on the inception date of DM being 94/94 E320, so I guess if it has a CE , it does, and if it doesn't , it's not there ........