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  #1  
Old 09-05-2003, 02:24 PM
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Angry Fuel distributor replaced and no change

I found used distributor on an engine a local tech had swapped out because the owner ran it hot. Tech said he knew the distributor was good because it was one of his regular clients. I opted to buy the entire airbox including fuel regulator, eha and MAF meter. Took it home installed it, flushed the injector ports with the fuel pump before atttaching the fuel lines. Installed it with six brand new Bosch injectors. I start the car and hold my breath. Let the car warm up and hit he throttle. Black soot from the pipe just like before. No amount of adjusting the 3mm mixture screw will stop it. Another $550 down the drain.
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  #2  
Old 09-05-2003, 04:35 PM
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If this is true even with the EHA disconnected, then primary pressure must be too high - e.g., bad pressure regulator.

Steve
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  #3  
Old 09-06-2003, 12:11 AM
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Well, you're not alone. From my experience, fuel distributers are the single most mis-diagnosed part in the world of gasoline-powered Mercedes.

Ron
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  #4  
Old 09-06-2003, 09:59 AM
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Can a plugged cat cause this? I know mine has been saturated in soot for a while now.
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  #5  
Old 09-06-2003, 11:10 AM
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I have tried to only express technical opinions in this and most other posts.

Every once in a while I like to point out how cheap it would be to have a professional deal with the problem. Your in deep do-do now because you have neither the ability to test the new distributor or evaluate your current condition. I only say that because of your volunteered past results.

If you have 5 cylinders with no flow and 1 with flow you can condemn the distributer, but unless you find similar simple results with the new one you will never know.

One out of ten cars that I do diagnostics on (I only do the tough ones) busts my butt, but not the customers.

Let me tell you about one: it was a 1990 300CE (104 motor KE). I picked up the car at the customers houes and thought it might not make it in. it was raining hard. By the time I got the scope hooked up for a drive, it ran fine. Over the next few days I drove it a lot with my scope set to take a snap shop. The way the snap-shot works is I can choose the time interval...up to 30 seconds. I also can choose where my set point fits in the 30 seconds. Standard setting is I feel a problem and hit the snap-shot button. What I see then is the previous 15 seconds and the next 15 seconds from that point. Over a few days I caught misfires on three different cylinders. I tried plug wires, dist cap, coil, rotor, everything except the ignition conrtroller. I almost changed the crank sensor. I walked.....

One of my better techs that works next to me had been following the process and the car was parked next to him so he took the plugs out to see what he could see. What he saw fixed the car and it had nothing to do with the state of the plugs. What he figured out was the wrong plugs were in the motor! Never seen such a thing and its possible we put them in there. The plugs that were in the car were right for a 103 motor but not the 104 motor. They are the same heat range, same size, but they have a different seal type. One uses a washer and the other a conical seat. What this did is put the plug into the plug hole, which caused a misfire under heaviest loading conditions like high humidity and the load that comes from starting off in second gear.

I could go on for hours telling such war stories. We had many hours in that car, lots of dyno time and a bushel basket of parts. The customer is the city manager of a local town and has a city crown vic (police special) as a daily driver so the time we spent doesn't bother him. There will be no bill as it is very likely we put the wrong plugs in. (although we can find no records in the last two years... he doesn't drive the car much though).

Actually there will be a bill though as he was so happy we found it that he is going to fix that leaking head gasket.
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  #6  
Old 09-06-2003, 11:59 AM
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so how do you deal with situations like this?

I was wondering how a professional would deal with a situation like this?

$550 is no small potatoes, and it still didn't fix it. I would be quite frustrated at that point, but if it was my car, and my diagnostic skills that reached this conclusion, I would accept it as the price to pay for learning and move on, but the bottom line is the car still won't work.

Cap'n, is there anyway you can toss the cat completely? Just stick a piece of straight pipe in there instead and see what happens, it should not cost much at all, and if the black soot is coming from the exhaust, then there might be something stuck in the cat causing this. I don't see how the engine would produce the soot unless you are burning oil, and you're not are you?

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  #7  
Old 09-06-2003, 01:45 PM
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Its hard to express how a professional would do it. To you it looks like a mountain to climb. To me its what I do every day. Likelyhood is that the problem is so simple I wouldn't even see the car in my shop (I only do the hard ones).

Most problems, even for experienced techs, boil down to something simple camaflaged under some poor assumptions. How about another example of one that toasted our...you know.

My best strategic tech does most of our BMW diagnostic work. He wound up on a 93 Audi 90CS 2.8l v6. The car is brought to us by the cheapest car wholesaler (that is cheapest wholesaler not cheapest car) in town. Knowing the source we should decline the business, but we are good guys.

The story is that it is a no start. He has already replaced the crank sensor. (keep track of the camoflage). We test the car and sure enough it has no spark signal or injector signal. After doing pin-outs of every terminal of the controller we have found that the controller is awake and capable of displaying fault codes. We cause a couple to be sure. Other than the codes we cause there are no codes. While testing all the controller inputs we come across some problems with the signal from the cam sensor and we replace it. Still no ignition or fuel pulse signal outputs from the controller. We are about to bail as with the known status of the customer we know he will whine after we charge him for the first hour of labor and there are a shop full of real customers cars.

Our diagnosis at this point leads us to thinking it is a controller issue. We spend some time finding a real cheap used one ($125) and with it installed there is still no ign or fuel control. *****!

At this point the professional says: I'll deal with it tomorrow! (as of course this problem has risen to my level - I of course suggested the cheap used controller at my tech"s controller diagnosis - diagnostic risk management is also my specialty).

Well what would you do??? I did the same thing, I went to the iATN archives and looked the problem up and in about three posts I had the answer. Those damn "A" fools have a engine protection strategy that turns the ign and thus fuel off when ever the syncronicity of the cam and crank are off by more than one tooth.

About an hour latter that thing was running like ***** with its cams adjusted and 65psi compression in each cylinder. This is where the professional really can get beat up. I should have turned down the job knowing the source. I/we were lead astray by his original work with the sensor and the further finding of no electronics. Normally we probably would have went right to cam timing. OF course when we take it apart we see the crayon marks and new belt where they had screwed it up... do you think they would tell you they did such? The job is just packed with irony, a psych would maybe have done better. The fact that we didn't know Audi used this unique strategy without setting a code amazes me but we will chock it up to learning and the fun of the final kill.

A professional handles it anyway necessary. A real professional then figures out what that problem should cost and charges for it. As it turns out a real professional wouldn't of had the problem as he would have known that startegy, least all those archive replies were from guys who had been there!

It wouldn't be fun if it was easy, but it is unfortunate that there is no way for me really to give you all any clue how far in the dark you are compared to a professional. The typical DIYer only lacks three things to keep you from having the same problems I do: Training, Experience and a half million in tools. Otherwise we could all do brain surgery!
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  #8  
Old 09-06-2003, 03:12 PM
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Cap'n Carageous, I see you live in Georgia. Why don't you drive the car or tow it to Steve B? Just a suggestion.
Meza
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  #9  
Old 09-07-2003, 01:23 PM
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Lastest on the fuel distributor saga

I dropped the exhaust pipes at the manifold. They will only fall about an inch but that's enough to 'see' the exhaust coming out. Start the car, let it warm, not a puff of balck smoke to be seen!! I hook up my DVMs. EHA is 20ma KOIO. Start car. Duty cycle varying continuosly between 47 and 52%. EHA steady at 3.6 with O2 sensor unplugged and near zero connected . Still not a puff of smoke of ANY kind to be seen, even when revved to 4000 rpm. Damn that thing's LOUD at 4000 rpm.:p

So, plugged exhaust making it run rich???

Last edited by Cap'n Carageous; 09-07-2003 at 04:40 PM.
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  #10  
Old 09-07-2003, 03:55 PM
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There you go Cap'n, it took me six months to figure out why my car was hesitating and like Steve said, it was something simple, someone didn't know what the EHA current should be set to.

From Steves story I would have to agree with everyone else that the best way to start solving a problem is to look at any recent repairs, I'm sure that would make things a lot easier in the case of the audi, but then again, someone people just don't like admitting to screwing up, yet it is a part of every day in the life of every human being

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  #11  
Old 09-07-2003, 05:24 PM
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Frankly, I'm in complete agreement with stevebfl. Being a do-it-yourselfer is a wonderful thing with many advantages, but it's important to realize one's limitations. And by limitations, that's not necessarily a consideration of just your personal skill or experience, but also of tools and equipment that you have at hand. Mercedes gasoline fuel systems are extremely complex and require certain diagnostic equipment that very few people have access to. And the fact is that many of the components involved are simply too expensive to simply swap out and cross your fingers.

Ron
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  #12  
Old 09-07-2003, 05:33 PM
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You "experts" are preaching to the choir here. I HAVE taken it to a tech. There ain't but two in this area. One is a known ripoff and the other kept it all day and didn't fix it. When faced with little or no choice you do what you have to do. Now, when all the philosophy moments expire can someone answer a simple question. Why does this car blow soot through the pipes and run lean out of the manifold?
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  #13  
Old 09-07-2003, 05:34 PM
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Quote:
Being a do-it-yourselfer is a wonderful thing with many advantages, but it's important to realize one's limitations.
- I have about come to realize that the W123/126 turbo diesel is about as complicated as I want my car to be (not considering the Honda which is pretty simple itself).

Cap'n I would suggest either getting a W123/126 turbodiesel or building a manifold that will allow you to bolt on a Holley. Throw in headers and a straight pipe and it should be ready to roll in Gum Swamp.

You ain't brought it to me Cap'n. Bring it by sometime and we will check it out.
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  #14  
Old 09-07-2003, 05:44 PM
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Hey Eng!!

BTW, What color do you want your room in the "Better Homes and Gardens Shop"???
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  #15  
Old 09-07-2003, 07:58 PM
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How does the backseat sleep?.

If she is ever successful in running me off paint it "broke blue".
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