Do not let anyone do another thing to that car until they know for sure what exactly is wrong with it. A good mechanic should be able to figure it out without throwing parts at it. Anyone can do that!

Finish running that cleaner through your engine. Change the oil once it's done. Build and then use the code reader!

As cold as it is right now where you live, that "white smoke" just might be steam.
Regards, Eric

I agree. The code reader should not have been a skipped step.

I am a little confused . From what I have read the code reader that I build will pull the codes that the dealers scanner that plugs into the 39 pin connector will , at best.
I watched him use the scanner when we changed the fuel filter last week . Also my friend / dealer mechanic who I know for 15 years said it gave him no codes.

Are you saying the code reader I would build would find codes when the MB scanner would not ?

Both of these mechanics are Techs . Do you think I could do better on my own with the code reader than they can with all their equipment

Eric do you think the code reader I would build is better than the 39 pin scanner that 2 Mb mechanics have used? I have physically watched him use it and draw no codes . What will I gain by using the one I build.

PULLED CTS SENSOR
 

Someone suggested CTS sensor since it only happens when car is warm. maybe I could fool ECU into thinking car is still cold.

Here are the results:
Well well Iive and learn . First I found the CTS sensor and when I looked at the wiring I saw some wire was exposed and the black covering sorta crumbled a little more as I handled it.

So much for the condition of my upper harness ( I think ) . I proceeded to take connector off engine with engine off , temp approx 95C pre disconnecting it , restarted and drove it around a little . No difference . Engine missed at the same RPM 1400-1800 under hard acceleration. Feathered throttle produced no engine miss as usual

So then I turned it off for about 1 1/2 hours to cool down and retry. When I started it again the K6JRF view in the climate control window on position #6 said LOW instead of a temp.

But the instrument cluster showed the temp approx 65C. Also the instrument cluster temp gauge got up to over 80 C in city driving , and back down to 70C on the highway . When I first start in the morning the cluster gauge shows below 40C and at that temp it never misses .

Now we know that the car has 2 independent engine coolant temp sensors. EUREKA

I left the sensor disconnected and drove home.
The miss/bogg was still there. Nothing seemed different at all ! Actually after a half hour of highway driving , and slowing down to 40 MPH and 1700 RPM an attempt at rapid acceleration without a downshift caused the famous miss/ bogg 2 more times and one time I was going slightly downhill.

The longer the engine is running regardless of temp at the moment , the more likely the engine will bogg down.

I am going to let the car cool down entirely overnight , so that I know I am at the same starting point and drive the car tomorrow,let it run 30-60 seconds , and see if it STILL NEVER MISSES COLD, and at what temp it will start to miss when warm as usual , with the CTS sensor on the engine manifold disconnected .

I am also going to build the code reader this monday

The above quote is from post number 58. Like I said, it is a known problem of MBs of that time period and all of your techs should have known to check this as a possible source of your problem which is why I have doubted their competence all along. Now that you know that your wire harness is bad, you must address that before you go any further. That rotten harness is causing your ECU to receive confusing signals from the sensors. And leaving the CTS disconnected is not the answer either.
Regards, Eric

Just as you say in post #58 the harness is a problem in these cars. When I first called my second Mechanic ,before even meeting him , he told me over the phone my year car was notorious for that problem. He said it was related to the Green Partys policy in Germany about wiring being ecologically sensitive, and biodegradeable . So I knew in advance , that he knew about the harness.

But then he said it is OK and I believed him . The wiring on the CTS sensor is supposedy one of the the most likely areas to break down.

Only one wire was partialy exposed and the other was fine . Does that necessarily mean the entire harness is bad? I am going to do a separation of those 2 wires and then coat them with rubber paint . Where else should I check the wires. I hear the connector by the injectors is next and I also hear that the harness usually goes bad in the engine bay, where heat is the highest and moisture is a problem .

I also am sceptical because this started the day after I put that questionable gas in the car. I am also sceptical becase it only happens when the engine is warm, and only when I try to accelerate aggressively in the 600-2000 RPM area.

If I choose to drive by accelerating gently, instead of aggresively, which is how I usually drive to baby my tranny etc.,I can drive for the next ten years without the car missing a beat IMHO. But I know this is not normal and that bothers me.

I will also inspect the rest of the wires myself. But my wifes cousin looked at them. 2 MB trained mechanics looked at them , and aside from what I found yesterday everyone said they looked good.

What happens if I just replace the harness, and it is the MAF that is bad, or the injectors, or the plug wires, or the coils, like my first 15 year trained certified Benz Mechanic said. Am I not just becoming a parts changer like the mechanics that we mention in this forum ?

I appreciate all your help and I am not being argumentative, but like you I want definitive proof of a part being bad , before I go changing it.

Which code reader do you advise I make

Make Jim F's code reader but you won't be able to believe what it says until you replace the harness.

Like I said before, the areas that are the most hidden are the areas that rot the most. Under the air cleaner, look inside the hard black housing that runs along the passenger side of the engine, you'll see some more scary wire insulation rot. And that CTS wire? The further inside the sheathing you go, the worse it gets. You probably haven't seen the worst area cause it's too far in.

I was told over 4 years ago on a thread that my harness was bad. I looked, checked and found nothing. I posted that they were all wrong and the wires were good. Three years later I was at a junkyard and saw an M119 car partially disassembled and saw that area inside that housing. It was scary! I went back out into the parking lot and immediately checked mine in that area. It was scary too! Yes, I've milked that rotten harness along now for over 4 years but that doesn't mean you need to. If it's bad, replace it. Even if it's not causing problems now, why wait for it. It won't be pretty when it get's you and it will be at the worst possible time too. I'm on borrowed time with mine. And it does have days where it causes me maddening fits. But at least now I know what's causing it.

It is true we do not replace anything unless we know for sure it needs to be replaced, but in this case, we now know it does so we should.:):D;)

Even if doesn't cure the issue, it wasn't wasted time or money cause it was something that needed to be done anyway.
Regards, Eric

I will probably replace it and do all the proper maintenance becuase I love my car. But I need to know what is causing this particular problem and fix that first. I want to eliminate that flat spot and being a hard headed Greek that I am I want to do that first.

Then I plan to change motor and tranny mounts , flush tranny, replace thermostat , gas up the freon, maybe plug wires or maybe later, and at least clean MAF.

But first I what to find out what is causing this hesitation when warm only.

My wifes cousin swears by a guy who does a cleaning process on injectors and who said the throttle body could need it also . may try that plus cleaning the MAF first .

Now I am taking the car for a ride with the CTS sensor disconnected .I will post my results .

Thanks again

Again I appreciate your thoughts , but I would still prefer to cure the problem , which in my case is very slight and can be avoided by just not stomping on the gas till after 1800 RPM .

In reality if I was not an obsessive perfectionist , I could drive this car the way it is for prolly another 50K miles. Two friends of mine have already said leave it alone and drive gently till it gets either better or worse.
One of them is a very close friend of mine , my skiing buddy , and a Doctor. He thinks I am nuts obsessing about it ,and he is a Psychiatrist . Leave it alone and just drive it he says .

Not good enough for me .
I must solve this problem , but not at a $1500 or $2000 cost on a gamble .

My cousin recommended a guy named Chris who has equipment to clean out fuel injectors .

I went to see Chris.He works on all types of cars. His shop does oil changes and various other things. He was helpfull and we took the air filter housing off and he said the Fuel throttle assembly was spotless. He said it looked like it had been cleaned very recently.

I told him Joe my BenzDealer mechanic had it for a few days and changed plugs etc. and maybe had cleaned it

He said it looked like it was clean, but then sprayed some CRC Mass Air flow cleaner in it while it was running.

We looked at all the wires , vacuum lines etc., and he thought his $70 process would be a waste of money so he did not even do it. He thought MAF would cause a rough idle and not the symptoms I described , but admitted he was no Benz mechanic and recommended someone else for me to see IF I wanted to.

While we had the hood open I saw that the sensor beneath the coolant tank was not plugged in or in its bracket . Prolly from the time I had my coolant changed or one of the mechanics who has been looking in there disconnected it , to check it and forgot to reconnect it , and put it back in its proper place.

After we closed it up I took it for a ride , same thing, miss on heavy acceleration with engine over 70C .

Chris said when it is running cold , it compensates for the lean mixture by giving it more fuel, thats why it never misses/boggs when cold .

He liked the FUEL REGULATOR not working properly theory someone postulated in another forum a lot.

Willy the guy I am using now (Let me give him a name so you do not confused with the first guy (Joe dealer mechanic ) who up until today, had said it was prolly injectors ,and today changed his mind to coils, said that tomorrow he might be able to swap out a coil. It migh be injectors was his first thought. Thats after changing caps and rotors which we did already .

Chris said in his experience electrical things usually work or they dont . He thought coils was unlikely to produce my symptoms. Does anyone agree or disagree with the coils theory applying to my symptoms

It drives so dam well when past 2000 RPM etc and I had it going at 60-75 MPH today off and on for an hour. The only thing is at those speeds engine really cools down to approx 70 C so engine temp is lower,therefore the problem is eliminated ? Only runs bad when warm and pushed under load.

I dont think I know enough about sophisticated cars from working on them in my youth mostly. But the way it drives after it gets past 2000RPM is wonderful. It feels as good as when I got it with 29 K miles on it 15 years ago.

Aside from that one little glitch it performs flawlessly. Its peppy on the highway ,starts up easily even when sitting out for days in the freezing cold idles like a kitten and accelerates wonderfully by downshifting or just applying more gas , after 2000 RPM.

Chris looked at the harness and said it looked good . I find it hard to believe it is top harness.

Hopefully I will get Willy to swap out a coil tomorrow to disprove that theory.

Maybe I will order the Pressure injector and have someone else put it in since Willy doe not think its the problem . Is that an easy part to change ?

Any more creative ideas, that can tie together my symptoms, and lack of symptoms ,to eliminate things, and then be left with the only sensible deduction .

What do you think of, keep on running it hard and letting the gas run down to almost empty, like 1/8 tank and then refill with additive?

Well with luck Willy will swap out coils tomorrow and rule them either out or in , and I will either know, or the process will go on.

Replace the harness first because it may be the cause of the problem! If you don't replace it and it is the cause, you will continue to chase your tail forever!

Again, to really be sure about the condition of that harness, it must be checked the way I described in my earlier post. Has that been done yet?

I'm glad you admitted to your hard headedness! Now I don't have to say anything about it.:P;):D
Regards, Eric

I checked the CTS wire as you suggested . Amazingly it was only degraded for approx the first 1/3 inch or so. I pulled the sheathing back and separated the wires with a toothpick and put electricel tape on it.

Many people have checked the wiring although no one has cut into it with a knife YET.

I will have Willy look at it better today. WE are going to swap out coils today, and look it over again , and if he has some lying around we may swap out injectors.

He does not agree with the Fuel Pressure theory but if we do not find anything I may just bring it to someone to change if nothing else works.

The theory of running out the gas is still in play because the symptoms appeared the day after I bought that questionable gas.

Hardhead LOL

SUCCESS ! IT WAS THE COILS
 

Well I went to see Willy today to swap out coils that he had on hand to be installed in a 400E that he was rebuilding.
When he pulled the old coils , we noticed one of them had white residue by the outlet (orange) end . He said it looked like it was arcing.

We changed them both and I took it for a test ride.

Success. BAD COIL IS THE VERDICT . I drove it till engine heated up to 98C, up and down hills almost WOT and no flat spot just smooth acceleration . Drove 30 miles home, and in city traffic etc and it definitely is fixed.

He said harness would be a good idea , no rush , but he will look for a good used one from the junkyard that he can find that was replaced and not the original harness. I emphasize good idea , not the cause of the problem. The coils were the cause of the problem . The harness would be good maintenance.

We got to the cause of the problem . Sometimes its good to be a hardhead. Or as some people would say DETERMINED

Talking to other benz owners I heard stories from a guy that has 95 SL with 150K and all original parts except brakes and tireshttp://images.intellitxt.com/ast/adTypes/2_bing.gif. Willys mechanic has a friend who is running a gas 93 SEL benz with 626K on it , and Willy himself has a 1988 WITH 425k that the only real work perfoRmed on it was a tranny rebuild. All were gas engines

Actually it is a little ironic. One of the two original partners that looked at the car thought is was coils, while the other thought it was caps and rotors.

So, had I started with the caps and rotors partners suggestion , I would have spent $1100 and just got new caps/rotors and coil.

In spite of all the time I spent for the same $1100, I got new caps / rotors, coils, spark plugs, 3 spark plug suppressors, fuel filter,and brake booster hose , plus was fortunate enough to find an honest person , willing to swap out parts when he could, and not taking your eyes out .

I also got to familiarize myself with the car so I have an idea how to access different parts and periodically check hoses etc myself.
It was very educational !


What amazing cars, when taken care of .

Thank you all for your suggestions.

P. S.
Remember we got no codes from 2 scanners . The lesson is scanners are not perfect either.

Also I hope this may help someone in the future with similar intermittent symptoms

Glad all is good now!
Also glad that harness is gonna get replaced.
Please remember, those spark plug wires are gonna need replacing too at some point in the not too distant future. Keep an eye on them!
Regards, Eric

Thank God for the problem being found. I'm going to go look at my electrical system now.