Idle problem - 94E320 HELPPPP
 

First of all, I would personally like to thank Gillybenztech for assisting me with this problem. Last week, I had an emissions problem so I had the air mass sensor changed. The cars idle fluctuated from 500-1000 rpms in the park position only, otherwise ok.

After having that part installed, the idle stopped fluctuating in the park position. But then I got an irratic idle. THE IDLE WAS FLUCTUATING FROM 500-700 RPM AT A STOP SIGN OR RED LIGHT IN THE DRIVE POSITION WHEN STANDING STILL. Sounds like "VRM VRM VRM VRM". When the car accelerates it's fine. The car surges forward then back only when I'm standing still. After 10 seconds or so It would stop.....the car gives up!!!! I can still drive but at the stop sign or red light I have to put the car in neutral.

The damage....idle speed conrtol unit....02 sensor $1,450.00. I've read on the boards that I might not need one. I know that I will need to spend money on this one but certainly not $1,450. The 02 sensor is not directly related...that's for emmisions.

Throttle Actuator?? self adaptation?? engine wire harness??air slide valve??? used tested idle control unit????

The car 99K on it. The car is at the shop waiting for my decision on Monday Jan 14.

Thanks,
Ron

BY you description I would say the throttle actuator is defective. List price is $1,100.

Welcome to my nightmare. Had same problem last week- required Wiring Harness, and Throttle Actuator. Dealer paid parts cost on Wiring Harness, but I'm still out $1500. This after having a water pump and Battery replaced last week. Lousy track record for a garaged, Dealer serviced '94 E320 with 86k on it. This is my 3rd MB, but it may well be my last.

davey I totally understand what you went through. I guess that the idle control unit and the throttle actuator are one of the most expensive parts to replace. my mechanic says thats its the ICU.
I will definately mention the throttle actuator. I guess hell test it.
my rough first month!!!
could someone explain in a few sentences the function of throttle actuator. Is this also called throttle motor?

"Theres always a better way"

I have tested and replaced many of the throttle actuators and none of the control units. The throttle actuator is an electronic accelerator of sorts. It controls idle, cruise and accel functions. One easy way to test is to see how well the cruise works. An ill cruise system is an early indicator of a faulty throttle actuator on the 104 engine.

I would test this circuit then cut open the throttle actuator harness to see the wires inside. My bet is that they are faulty.

Hi Ron:
The throttle motor is part of the actuator, it's all one assembly though. In it's simplest description, it controls the throttle (the butterfly valve in the venturi). They went to this when they wanted to incorporate control of the throttle into the anti-skid control (traction control). They figured "what the heck, lets do it electronically all the way, then we can use it for idle control and cruise control too". My experience on bad ones has been mostly with the 119 motor V8, the 104 motor I can't recall replacing one personally. I think the heat gets to them on the 119 motor, it has to get hot practically buried in the valley between the heads. Usually they are going into a back-up mode called "limp home mode", either that or they idle bad like yours is.
I still maintain that since it works OK off idle, not in limp-home mode, and that the air mass meter was replaced, that the tech may have reset the self-adaptation of the fuel trim and neglected to reset the throttle stop position. I believe that on these, you erase the throttle valve stop (electronically) when you reset the self-adaptation. Maybe the tech is unfamiliar with this procedure and started learning the throttle stop, thought it was done and removed his scanner early? Given the scenario, I would "back up" and look things over more closely, at least try having the throttle stop relearned before going this route. Just to much "coincidence" for me to start ordering parts already.
Gilly

good points gilly and donnie. thanks. I will look into the self adaptation and check the wireharnesses. If it isn't good I will have Mercedes replace it under warranty. $500 otherwise.

the problem is that this mechanic is the shops owner...20yrs+. he said he pulled the codes etc. Hence idle control box or unit. He might actually mean the throttle actuator because he said its the box that controls the cruise control etc. You guys feel its the throttle actuator. I'd like to go with you on this one. I read in one of your posts that you have never replaced the control units and that you could see this only if the throttle actuator is faulty and it blew out the computer. You also mentioned that if you replace the controller without the actuator then it will eventually blow too.

so now you see I'm a little worried. He puts in the new unit and a month later the faulty actuator messes it up.

either way it looks like a big job. well now ill be prepared for tommorows showdown!!! I'll keep you all posted...stay tuned

Well eventually I had the throttle actuator replaced but that did not solve the problem so my mechanic removed it. He installed a new Engine wire harness becuase he felt that both parts died at the same time.

Problem still not solved. The computer is now showing that the idle control unit is faulty. One of the most expensive parts for this car and it has to be programmed at the dealer.

We will first install the actuator and see what happens. The dealers in my area would not install the harness under their good will policy.

Has anyone else been through this? Any thoughts?

Ron:
I'm confused as you state you will "first install the actuator and see what happens". You said you had the actuator installed and it didn't fix it.
I still maintain, unless the mechanic states otherwise, that the throttle stop may not have been learned. They will run like this if the stop isn't learned, and this could all go back to when the air mass sensor was replaced. If he reset the adaptation and didn't relearn the throttle stop it will run like this.
Does the mechanic say there are now codes indicating a faulty EA control module, or does he just "think" it needs a new EA control module?
Gilly

Gilly,

He just put in a new wire harness. Before he just put in the actuator or air slide without the wire harness.
So now he wants to put the actuator back in.
But the EA control mdule is showing faulty code....a $1,200 part.

I heard in the past that the diagnosis machines are sometimes wrong.

I am pretty sure that he relearned the throttle stop. I will double check.

Buy the way, does the EA control module need to be programmed at the dealer?

Ron:
Usually the codes aren't really "wrong", but alot can be left up to interpretation.
See if you can find out what the code is in EA and myself or Benzmac can tell you what we think.
My thought is that the mechanic may be thinking "lets see, it wasn't the actuator, it wasn't the harness, hmmmm, must be the control module". I can't say that's what's going on for sure, just makes you wonder though.
Gilly

Gilly and company:

We just installed the air slide valve or actuator. We decided that since idle control units rarely go bad we decided to replace the air slide. To update a new engine wire harness was put in a few days ago.

Still the problem exists - irratic idle. The computer is showing Idle control module faulty code... but I Did not see it. Since he cannot program the module he is recommending that it be taken to the MB dealer.

We have not decided if we are going to remove the actuator.

Ron

Ron:
Go ahead and take it in. I'd like to help, it sounds like no one on that end is listening to my suggestion about learning the throttle stop, I still maintain that this may be the only problem. Maybe the guy doesn't understand this needs to be done when replacing the throttle motor (throttle slide=same thing, tech definition vs. part definition). When he went back to the original, it needed to still be relearned. I think he's chasing his tail now. When the throttle stop is not learned, it will drive OK, except when coasting or at idle, it won't idle correctly.
It may learn it by itself if you just turn the key to "ON" and wait a minute of 2, or it may have to be put in to the learning mode, it seems like this varied from system to system. If it's learning it you will hear a strange electrical motor sound (like a whining or high pitched buzzing) as the electric motor runs the throttle plate from one stop to the other.
I am especially skeptical because now he seems to be backing down from his assertion that the EA control unit is bad and suggesting the dealer. If he has a fault code for a self-diagnostic failure of the EA control unit, why not accept it and order the control unit? I'm sorry, I don't know if this needs to be adapted to the specific car or not, but I do know you sure as heck will need to learn the throttle stop!!! Also why didn't he give you the fault code that is telling him that the EA control unit is faulty? "You didn't see it" makes me think "He's bluffing". Good Luck!!!
Gilly

Same Problem!!! Same year!!! Same diagnosis
 

I am having the same problem. My car is hard to start unless I keep my foot on the gas. Stalls in stop and go traffic if the A/C is on, no A/C...runs fine but idles low and surges occasionaly but no stalls. I just got it back from the shop and the Tech said the Cruise Control/Idle module (P/N 0001415725) is the problem. I did not see nor did he provide the code. The cost is $750 for the part (new) and about $275 Labor. This has been going on for quite sometime and for that kind of $$$ I figure I can live with it for now. Just had the wiring harness done for $750 and this car is starting to become a money pit. New Alternator $550. Motor Mounts $280. Belt Tensioner more $$$. On top of my $500 + car payment (paid off in July) you can see my frustration. I feel your pain! BTW, I found one of these units on a slavaged car for $400 w/ 90day warranty.

toyberg.

If you are in Southern california, Give MR. MB motors in tarzana a try. Enrique is an excellent mechanic, and has always done great work and provided excellent diagnosis on our family cars.

I try to stay away from the dealers unless I need a part that day.

Alon

engine cut out at idle
 

Hello Dan Gillitzer,

I have read your replies in this threat with big anticipation. You are the first that describes the problems I have in a fitting way. I have a 93 280E (US 300E 2.8 I think) with ofcourse the 104 engine. Since a while I am having problems with the engine cutting out at slowing to a halt or coasting at a regular speed. The problem will not be there after a cold start, she will run fine. After warming up the engine and caosting at a nice pace on the highway the engine wil start to hick up without a sound, it feels more as if the car is hit witha gust of wind from the front. It will do this once or a few times in a row. This problem is more present when I hit a bump in the road, this will be immediatly followed by a hick up. If I come to a halt or slow down to very low caosting just before making a turn the engine may cut out without a sound or the idle will be safed by jumping up and then normalizing. If the idle does not fall through it is normal, 650 rpms in D. The idle is a little unstable but then the engine ahs done about 90000Miles so what could I expect.
I have sofar replaced the oVP, fuel pump relay, spark plugs, air filter (even tried a K&N replacement one). The car has had regular maintenance at the mercedes shop so I asume that the etrol filter has been exchanged at the time that it should be.
It seems as if the problem is getting more frequent over time.
I figured that I have to do with a loose wire or sensor since the problem will be apparent when hitting a bump but if I run the car at idle and fiddle everything that I can see under the hood, or even hammer it to copy a bump, I can not reproduce the problem.
Does any of this sound familiar to anyone? Could it be a loose wire or a vacuum in the fuel system?

I am not very technical so please, if anyone has answers or question keep it slightly in laymans terms.

I would be gratefull for any suggestion or info.
Thanks,

Marc

Marc:
Since your car isn't (I assume) US spec, I have to make a few assumptions, mainly I assume this is a SFI (sequential fuel injection) engine, probably LH or HFM-SFI, both really the same system, only the design of the mass airflow sensor is different.
If this is the case, I would start to suspect the engine wiring harness is the problem. There are a number of places this can be checked, although some of the areas may not apply to a Euro spec engine. The places I can usually make a good confirmation on this problem are the front of the cylinder head. The plastic panel needs to be removed, and there may be a couple switch-over valves under that. There will be electrical connectors on these switch-over valves. There are conduits over the wires for these connectors, sometimes you can see the insulation cracking off the copper wires just by observation of the wires coming out of the conduit, if not it may be adviseable to cut back the conduit to see more of the wiring. What happens is the insulation gets brittle and flakes off of the copper wires. If this happens in places where the copper of different wires can touch, you can have various problems, including the symptoms you have described, although I have to admit that by your description, it really sounds like the overvoltage protection relay, but you've done that already. Other places to check for a failure of the harness is the harness for the mass airflow sensor (harness outer covering needs to be cut open though) and the individual wiring connectors for the injectors. On a US car, usually you will get a "check engine" light, but a Euro-spec car I know has different equipment in this regard. Maybe there are stored codes in the engine management system similar to a US-spec car which may indicate the failure going on, even though there isn't a "check engine" light like a US car?
That's the best advice I can give assuming it is a SFI engine.
If it isn't SFI, if it's a CIS-E engine, let me know. If it's carburetted, you're on your own!
Gilly

Thanks a lot Dan.
 

Hello Dan,

Thanks a lot for all this information. I will check up on the areas that you mentioned. I have asked the benz dealer to check for error codes but they said that there were none. They also told me that they replaced the OVP. Maybe I should make really sure and replace it myself so at least I am really certain that it has happened. Nothing surprises me anymore when it comes to making money.

At least it is not a carburretor engine but a modern 24 valve one.

Yesterday I took out the airmass meter, it looks like a very thin copper plate with three or four flat steel plates soldered on to it. It is about half an inch high and even less in width and is about 2 mm thick. What I did found out is that the clamp that holds the housing of the metertight into the following rubber sleeve was fairly loose, thus giving the possibility of false air being sucked in after the air mass meter. An other thing is that the hick ups at caosting doesn´t really start then after coasting on a nice speed (90-95 Mph). If I hit the freeway and coast at only 60 miles it seems to take much longer before the hick up starts. After it starts theer is no stopping. The wiring I agree with since the hickup can almost be provoked by hitting a bump, this does sound like something mechanical.

I will try what you suggested and let you know the outcome.

Thanks a lot,

Marc

How MBZ get's around a design flaw
 

I had the same symptoms with my 1995 e320w and took it to the dealer since it was still under the 100K emmsion warranty in Calif. The dealer first said that the pick-up magnet on the flywheel had fallen off and the trany would have to come out. I guess when I looked at him with my "You must be smoking something" look he went back to his service forman get a better answer. The answer was that I needed a new wiring harness and it would take 12 hours to install. I had the head of my 300TD in half the time. I did not beleive the answer and decided to wait and call MBZ customer service. The next day the dealer called and said they would cover it under warranty. I did some more research and found this to be a common problem do to a change int he insullation wiring spec for a couple of years. This should be a recall item. My uncle who had the identicle problem took it to his local gas station and had the mechanic install it for him. He bought the wiring harness and by the mechanic. It took 2 HOURS for the uncertified mechanic to installit at a cost of $190.

I HAD THE SAME PROBLEM
 

YOURE ALL GOING TO THINK IM CRAZY SAYNING THIS,, IM NOT A MB MECHANIC BUT I HAD THE EXACT SAME PROBLEM ON MY 1994 E320 LAST WEEK AND I TRACED IT DOWN TO A SMALL LEAK ON THE VACUME HOSE THAT GOES TO THE THROTTLE VALVE ASSY.. A 5 DOLLAR PART FROM MERCEDES BENZ.. NOW IM HOPING SINCE YOU VE HAD YOU R CAR TO THE SHOP THAT THEY WOULD HAVE CHECKED THAT FIRST ,, BUT SOMETIMES WE OVERLOOK THE SMALL THINGS AND MAKE THE PROBLEM BIGGER THAN IT REALLY IS!!!:D

who knows
 

Hello All,

Again thanks for all the info and tips, Jay, where is that hose situated that you had replaced? There´s a photo of my engine bay included in previous post in this thread.

Gilly: I have checked the wiring harness and the insulation of the wiring itself looks good, not brittle but flexible like it should be. So it either has been replaced or has never had the problem. I checked the spark plugs again because I also read some threads on those. I had exchanged them for copper core Itanium ones from Bosch. The tips were clean but light grey, I think this indicates a lean mixture going towards starvation?
While doing this I noticed that one of the ignition coils was not a 100% locked in position. When I pushed it to see if it was in al the way I could hear it click over the last part of the spark plug. Maybe this could cause a stall in a bumpy ride. I doubt it but one never knows and hope floats.

A lean mixture and a low idle are thingstha are not easy to change. I know from reading these forum threads that there are possibilities but usually the TEC speak is already driving me insane. If someone answers in this thread please describe the part to me visually and the location also. I have added a photo of my bay and can add photo´s of any part that I can see with my cam so that we can agree on what part is mentioned in a thread.

So far so good, I need to take her out today so lets see if she stalls or hicks after having the ignition coils refastened.

Thansk all and since it is a saturday morning here, have a nice weekend.

Marc:
Interesting about the coil/coils not down tightly. Let us know if that changes anything. Here in the US I use Bosch F8DC4 spark plugs exclusively, gap .8mm, torque to 29nm.
If it keeps having problems, i would try to rig a fuel gauge so yo know if you can eliminate fuel supply as a possible problem.
Gilly

In regards to the coils, the click/snap connection on these is not on the plug end themselves, but the plug connector boot/resistor to the coil towers. The plug end is simply a coil spring that rest on the plug from compression.
These are known troublesome boot/resistors and should be changed [ $8 ea.] Your car is HFM [my assumption-dist-less ign.]and when there is ignition failure, [ skip] , the ecu also shuts down fuel.
The other plug ends [ #1,3,and 5 hold up better as they are not trapped between the coil and plug chamber [ heat damage]
So, I would lift each coil and check that the boots all "POP' back on to the coils. [ better to change them at the same time]
The other click/snap connection is a screw shaft that the coil mounting hole [ only one per coil] slips over that has a clip connector for coil ground.
I doubt this to be the problem because , once the top inspection plate is secured, the plate mounting screws also go through the coils and ground/secure them.

Changing these 3 boots may/may not solve your problem, but are worth the $$$ and time in eliminating the possibilities ....

Hick up and stalling.
 

Hello All,

I use FR8D+ plugs with indeed a 0.8mm gap.

After making certain that every coil snapped and indeed one of them needed the extra snap I drove her around a bit on the freeway and on bumpy roads. And behold my amazement that so far no hickups and no stalling (yet). The stalling might indeed be caused by fuel shutting down after a misfire. If this happens while slowing to a halt the engine will drop to zero without even making a sound. So besides exchanging the OVP and the fuel pump relay this is about the cheapest thing I ever did to this car. Toke it out for a spin and really pushed the pedal later this evening,......no problemo what so ever!!!!!

I will keep you all posted if any trouble reappears. So far, really thanks a lot for all the tips.

Greetings,

Marc

>> I use FR8D+ plugs with indeed a 0.8mm gap. <<

Is that a plat/resistor plug ??

Plat/Resistor plug refers to a platinum plus I assume. No,...it is a new copper core plug. the super plus from Bosch. Havent had any problems with them so far.

See photo for packaging and typename.

Greetings,

marc

Hello Arthur,

I do have the idea that my coil was not properly grounded. The snap that I felt really felt as if the coil itself had to snap onto something on top instead of something deeper into the engine. It would also make sense that if you unground one coil, two cylinders are about to misfire and the ecu will shut down the injectors.

If anything happens I will let you guys know. Next time the cover comes off, I´ll exchange the connector bots. I have read about them being troublesome before so better safe then sorry for that money.

Thanks again and greetings,
Marc

Cool..
I have not seen them here in the US yet, but they should be fine.
Looks to be an up-dated Super /Copper, which is what seems to work best here in US. [ if you can find them anymore]
The "R" sort of indicated a resistor plug in my mind. Guess not.
The boots on the coils and wires are the resistor, so a resistor plug is not need.
Some countries call for different resistors and the US version uses 2K on the 104 engines. Your's may be different [ stamped on the boot, next to part #]
Would be interested in knowing such...

Good Luck

THE HOSE IM TALKING ABOUT IS VISIBLE IF YOU REMOVE THE AIR INTAKE TUBE THAT CROSSES THE TOP OF THE ENGINE AND LOOK STRAIGHT DOWN BESIDE THE THROTTLE BODY..(YOU MIGHT NEED A FLASHLIGHT.. THE HOSE IS ABOUT 3/4 IN ROUND ON ONE END WHERE IT PUSHES ONTO THE TOP OF THE ENGINE AND ABOUT 1/2 IN ROUND ON THE OTHER END .. THE HOSE IS ONLY ABOUT 6 INCHES LONG ALLTOGETHER.. SORRY I CANT USE MORE TECHNICAL TERMS BUT MY CAR WAS DOING EXACTLY WHAT YOU DESCRIBED ABOVE AND I TRACED IT DOWN TO A CRACK IN THAT HOSE.. WHEN I REPLACED IT THE IDLE AND EVERYTHING SMOOTHED RIGHT OUT.. BENJAY:cool:

Marc:
I'd get those plugs out of there and go with the F8DC4's, the R in that plug number indicates a resistor plug. These engines require a non-resistor plug.
Gilly

spark plugs not oke?
 

Hello Gilly,

Thanks for the warning. I stil have the previous plugs and they were fairly new so exchanging should be no problem.

What could happen if I keep driving the `R`plugs?

Sofar the engine seems to run fine on them, although I have the idea that the tips are too light grey.

I have driven her for some time now after clicking the coil in decently and I havent had her hickup or stall on me again. Every thing runs smooth and fast.

Please let me know about the plugs. Its a ***** of a job being an amateur but if I risk damaging anything I´ll do it straight away.

Thaks and have fun,

Marc

Marc:
I don't think the spark will be as good with a resistor plug in there. About the worst that could happen is to fry a coil, but it's probably safe to keep using what's in there, especially since it's running good now. If you get bored and have the time to change them, fine. I wouldn't consider it an emergency.
Gilly

sparks and spare time.
 

Hello Gilly,

Thanks for the fast reply, I was already worried about possible damage.

If the risk is that I fry a coil, expensive enough, I think that I wil have time very soon to change the sparks back to the non resistor ones.

The stupid thing is that Bosch promotes the R ones, at least these ones, for my car and says that these are the new stock plugs for mercedes. I will ak my local Benz shop.

Thanks again and have fun,

Marc

Marc;
The general idea is for them to cover as many models as possible per type of sparkplug. They are willing to take the risk that no damage will be done. Obviously they won't recommend a plug that will cause direct damage (impact with the piston for example), but other than that, if they think thay can convince enough folks to buy "triple gold plated, platinum tip, rhoedendrum core, solar influx capacitor equipped with mother-of-pearl insulators" spark plugs to make a profit, they will do it.
Bosch makes great spark plugs, but they have a marketing dept. just like the rest of them. Stick with the plain ol' "Super" and you'll be better off.
Gilly

I agree with Gilly.
Bosch is marketing their Plats to the point that we are having to run all over the place just to find Super/Copper. And we all know how some Benz Hate Plats !!
My thoughts on Resistor plugs for Benz with Distributorless Ignitions [ and I notice KYB is also recommending Resistor], is
that because each coil fires 2 plugs at the same time, you are now taxing the coil because the resistance is double. KYB's info page claims this is insignificant, but does not mention 2 plug firing.
[Also something to remember for those who like to open the gap past spec. Total gap is double for one coil]
So I stay with the copper and have been satisfied. [ and they cost less- which is not my motive].
Benz claims [ and I agree ] that the plug firing on the exhaust
stroke requires less power from the coil [ no load] in the "Waste Spark" type ignition. But I think adding additional un-neccessary resistance that has to be asorbed regardless of which stroke the engine is on is not for me......

I might go along with using a resistor plug and get rid of the resistor /boots that seem to give so much trouble , but doubleing up on the resistance does not make any sense except to the Marketeers ..

more on throttle actuator
 

Gilly,
I follow all these threads on the M104 motor to learn what I can. I saw with interest your comment on the throttle actuator and its relation to cruise control. My CC has been erratic and has not been working lately. It started working again sometime ago, but I had no occasion to use it. When I tried again recently it wasn't working again. I've already had the wiring harness replaced in the course of getting the head gasket done because it wouldn't run right after my mechanic buttoned it up. The car ran perfectly when I bought it (52k "low miles"). The oil leak just bugged the hell out of me so I had it done. It seems that disturbing the equilibrium on the car unearths all these little bugaboos. The only other symptom which seems to be throttle related is that a couple of times it wouldn't start on the first try in the morning. It felt like it was about to get flooded, but cleared up immediately after. I attributed it to some bad gas which I've had with some local stations but now I'm starting to think about this expensive part. I know it has similar problems as the wiring harness. Are any of these symptoms indicative of early failure in the throttle actuator? Should I leave well enough alone?
Thanks for all your help,
Joe

SUPER PLUS SPARKS
 

Hello Gilly and Dalton,

Thanks both for the firm language. I just exchanged my new Super plus (copper cored, not platinum) for the standard ones.

The local Benz shop told me that i could use the new super plus´s without risk. Arguing that if Bosch tels you it is oke for a 104 engine it is oke for a 104 engine.
They attributed the R in the product description to a radio interference block. So it had nothing to do with a resistorplug that might damage the coil but with a plug that does not make noise over the radio.
Whatever, just for my piece of mind I will drive the standard ones for a while. If they perform thesame as the new and improved ones I will just use the standard ones.

Thanks for the advice and I´ll keep you posted.

One more question: at 4000 rpm´s the engine gives a real kick. I do not know what causes this real surge in power. Is it the ignition, the cpu or the air intake that allows for so much extra power. Since I do not use the revs over 4000 very much i would be looking for a way to get this kick down to 3000 rpm´s or even lower.
Anyone any bright ideas?

Thanks a lot and happy motoring,

marc

<<at 4000 rpm´s the engine gives a real kick. I do not know what causes this real surge in power. Is it the ignition, the cpu or the air intake that allows for so much extra power.>>

It is a combo of the variable valve/cam timing, the ecu controlled ignition, SFI fuel management, and a big breathing feature-the
variable tuning of the intake manifold . There is a damper in there that actually changes the lenght of the intake for the higher RPMs. Top that with the 24 valves and you have a pretty powerful engine for a 6.
Don't know on the Euro's, but US is spect. at 217.
They are also known for having a flat torque curve, but suffer dead stop accelleration cuz of a 2:65 rear ratio [ which I like for cruisin.] That is helped a little with the 1st gear start.Considered a nice improvement of the earlier 124s.

<<They attributed the R in the product description to a radio interference block. So it had nothing to do with a resistorplug that might damage the coil but with a plug that does not make noise over the radio.
>>

I have not seen this plug here in the US, but R plugs are generally 'Radio Interference" plugs. And how they accomplish that is by adding Resistance to the plug.
Perhaps the new ones have some new tech that allows interference blockage without the resistance-- That would be nice.
Seeing that you have some of these and they are out of the engine, it would be interesting to do an Ohm reading from the tip to the electrode and see what you get , Do you have a meter???
The NGK page list there R plugs at 5K ohms.
Thanks ,
Arthur

R plugs.
 

Hello Arthur,

so the radio interference plugs are in fact resistance plugs.

Nice trick up Mercedes sleeve and bad advice at that.

I changed back to the non R plugs tonight and just took her out for a spin. No loss in performance at all so I´ll leave them in nice and quiet.

I do not have an Ohm reader but I do visit people that probably do. I´ll leave on of the R plugs in my car ( the trunk that is) and try a reading when I can.


Thanks for all the info,

Greetings,

Marc

Marc,
Cool,,, Anytime you have a chance to get one read, post it up..
just curious,
Thanks
Arthur

Marc and Arthur:
I can comment just on the resistor issue for now:
We're talking about the same thing when it comes to resistors and radio interference. The reason for the resistors is to reduce (or suppress) radio interference from the secondary ignition system. It is my opinion, and I believe this will be confirmed by consulting a Bosch spark plug catalog, that the "R" in a Bosch plug indicates a resistor type plug. Again, the only purpose I am aware of for the resistance in the plug, or in Mercedes case resistance in the secondary ignition wire end, is to suppress radio interference. There is no advantage, and in my mind a disadvantage, to having resistor spark plugs combined with resistance designed into the secondary ignition wiring.
Gilly

Gilly.
I totally agree. R allways meant Resistor plug to me and one thing I always like about Benz ignitions is they never opted for the easy out of going with resistance wires.
So adding another 5K resistance to the plug when it already has a 2K resistor sitting on top of it is a waste of ignition power.
On the older Benz, the Euro resistors were 1K , but the US versions had to have 5k in order to satisfy the US Gov. regulations on radio supression.

Arthur:
I'm not really sure if the gov't has anything to do with this (not sure, not saying it doesn't). It seems like usually when i replace a resistor end, it is a 1K resistor, and we do everything "by the book" so I'm sure it's the correct end. I do know there are other resistances, as you mentioned 5K, I think the 5K is a different outside profile, usually found on the older V8's (116/117 for example)with the "W" first spark plug number, and uses the larger spark plug socket to remove them. The smaller end I believe is the one which is 1K and is used on "H" type spark plug which uses the smaller spark plug socket, such as the 102/103 motor. I have the most experience in needing to replace 103 engine wire ends, the ends seem more likely than other engines to seize to the sparkplug, which ends up needing to be destroyed to remove, then the end is ruined to get it apart.
The need to somehow suppress RMI (radio magnetic interference) is a mutual kind of thing, as the offending vehicle with non-suppressed secondary wiring will be receiving just as much interference (zot zot zot zot) on his radio as the other vehicles around him.
It rarely occurs that anyone ends up with a non-suppressed secondary ignition. As Marc has found out, you have to really try to find non-resistor plugs these days.
Gilly

I don't know which Gov agency controls the rules of radio suppression, [ Maybe FCC or another enviroment control sorts],
but I can remember when Mopeds were first imported into the
States, they could not be Registered/ Inspected until a radio supressor/resistor was added to the plug wire end as it was not
a stock item.
So , I think there is some control on this . It may even be considered under emissions rules ???
I notice the 104 eng uses 2K.

I will do some homework on it.....

NON "R" plugs
 

Hello Arthur and Gilly,

Actually it is easy for me to get the non "R" plugs here in the Netherlands. They are still the standard plugs used by the Benz shop. I just stumbled on the R ones ( the ytriums) by acident. They were marketed by Bosch as the new standard on Mercedes etc. and I figured why not try them?

Well, I went back to the non "R" ones and am happy as ever to be driving a benz that does not stall or hick up.

The only thing missing is a 500E in my garage. The 300E 2.8 is a nice car but misses the kick of the 500E.
So who knows, maybe the next messages will be on a whole string of problems and frustration of the next project.

Thanks anyway and greetings,

marc

Marc:
My point being you are less likely to get a non-resistor plug "by mistake" for a car which requires resistor plugs as opposed to being given resistor plugs for an MB, which happens quite often when trying out an "exotic" spark plug.
Gilly

resistor plugs
 

Hello Gilly,

I stand very much corrected. I have been driving the non resistors now for a while and the engine does react much better.

Once over 2000rpm´s she pikcks up better and the overall performance is smoother. A little scare when the engine would again start to cut out. I changed the sparks back to the much newer coper ytriums to see if the nomn resistors where aging. Then engine showed the same error so i put back in the on resistors again.
The cutting out at idle remains as before.
Only in Idle and odly enough it happened the first time when going from D to R to back up into a parking place. Since then she does it regularly, mostly when nice and warm. More in D then in N but also there I have to keep the engine running by keeping the car at revs over the limitt of idle. No warning lights nothing.
It may be a coincidence but since short I can hear a distinct airbubble in the warm heater air. As soon as I put the heating on I can hear water running with airbubbles trappped in the system.
Could there be a conection. I know there is an article about this in here but I can not find it anymore. Any thoughts or tips here.

Greetings,
marc

Update

I am pretty sure that my irratic idle mess has been solved. I originally did not mention that I had problems with my belt tensioner. Just 2 weeks ago I put in a new one and had the temperature sensor replaced as well(fan wasn't working). Now the idle revs normal. Every once in a while it surges slightly then normal again. Just a few days after I had the tensioner installed it started making noises again and the rough idle surging Reoccured in drive and park. So I brought the car back to my mechanic and he made a few adjustments to the tensioner and since then (about 10 days) its been fine without the crazy surges. I really hope this is it!!

So if you dont hear from Then all is well....and thanks everyone.


Ron