For those who haven’t heard from me, this is PeterG from Chicago. After talking to Roy at Mercedes shop, he informed me how long I have been a member (2001) and haven’t logged on for a while, so I felt I needed to contribute again. I have over the years have obtained invaluable information from this site, and indeed thank you all.
Now it is my turn to give back. He also told me to update my profile as I have moved through 2 cars since. I sold my 79 300D ( I told the forum with pictures of my injection pump repair ) obtained a 92 300D which I sold just a little over 6 months ago with over 200K, and probably put less than 1K into it for the 3 years I owned it and bought my buddies 98 E300 with about 160K, and have put more than 2K into it in less than 6 months. I have had many problems with the 98 from plastic injection line leaks, Injection pump nozzle seal leaks to prechamber leaks, rear wheel bearing, and least but not last, the straw that broke the camels back, a failed mass air flow, and now the Turbo, waste gate solenoid valve failure. This put my wife over the edge to grant me the OK to purchase a new, or preowned e300 CDI. That is what this lengthy message is about.
It turns out on the 98, there are two identical solenoids. One controls the EGR and the other the waste gate. The part number is A-000-545-04-27. The patent number is 4,715,396, this is where we found a wealth of information on Google patent search. Over the past weekend, being a Failure Analysis Engineer, I removed the solenoid as I had no power/ boost. Prior to this I had the codes read by my very reputable repair shop, which indicated a problem with an air door (not sure of the scan tool he uses). I checked the diaphragm on the waste gate and then the vacuum lines. Everything looked fine. I removed the solenoid valve for the waste gate to see if it was working. I took it to my dungeon (shop) and first measured the resistance of the coil. It was about 14Ώ. I then proceeded to inject a signal into it, as I applied vacuum. It worked just like it was suppose too. I reinstalled it and took it back to my mechanic to clear the codes. The check engine light re-appeared shortly after he cleared them. I went back to the drawing board and found out a work associate had a scan tool to read the codes. We picked a fine day this week to perform this operation (Tuesday). For any of you there in Chicago we should have just as well been at the North Pole. We were able to scan all the sensors, and they all appeared fine, but the scan tool identified code P-243 waste gate solenoid. With this frustration I removed the solenoid from the car, and dragged it up to our lab at work. As you will see from the patent information the solenoid is not suppose to exceed 200mA at a full duty cycle (Full turbo boost). The solenoid looked fine at first, (low duty cycle) but as we increased the duty cycle the coil draw exceeded 400mA. Now it made sense. To the expert in our lab who built the pulse width tester we tested the solenoid on, he said the computer on the car looks at the current draw of the different sensors. If the current draw exceeds a certain limit, a current sense circuit disables the circuit, so it does not burn up the driver circuits in the computer. I thought I could correct the problem by switching the two solenoids, but probably because of the interaction of the systems, the computer disables the boost without an operable EGR. Based on the problems, the solenoid most likely has shorted turns. It is an expensive device, even the patent mentioned it. Mercedes wants $114.00, my mechanic buys it for $92.00, and Mercedes buys it for $69.00. Funny, the patent belongs to Borg Warner.


PeterG

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PeterG