Date registered: Nov 2005
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How I repaired and Improved my ETA.
ETA - Electronic Throttle Actuator
Pictures to follow in a day or two...
My 95 E320 Cabroilet had the infamous deteriorating insulation in the harness leading out of it. I've just finished my repair and although I have not yet installed it, here's what I've done. I mapped out the harness and removed all the bad wiring and replaced it with new (not easy, but not impossible). The biggest problem with wiring in a new harness is getting a plug for the end of the harness. While looking at some other ETA's at the shop where I usually go for repairs, we noticed that one of the old ones they had taken from another car had the OPPOSITE connector on it. It turns out that Mercedes seems to wire some with a female on the harness and some with the male (I assume so that you cannot put the wrong one on different models). This made my search for a plug easy. We just went through the boneyard looking for a donor car that had the plug I needed hanging from the wiring harness. We cut that off with about 3" of wire hanging out (checking of course to see that it did not also have the crappy insulation).
I went home with my plug and bought three spools of wire (blue 14ga, white 18 ga and red 18 ga (you can use any colors you wish, it's not likely you will find the colors MB uses). The bigger wire is used for the two wires leading to the motor, the other wires are for sensors. With a soldering iron and a solder-sucker it's not too difficult to remove the old wires and solder in new leads (after carefully mapping out the pin positions of each wire). Then you must clip the wires to the right length to mate with the leads on the plug (placing shrink wrap around everything and shrinking in place after each joint is soldered). All this is tedious but not that hard.
Here's the "improvement" that I made to my ETA. The ETA provides for "fly-by-wire" throttle advance (and cruise control). When you press the accelerator pedal, it merely moves a sensor in the ETA which tells the computer how much throttle you want. The computer then sends a signal to the motor in the ETA that moves the throttle plate. I've noticed that my car has a small amount of lag time between my input and the computer response. It's just enough to annoy me. Also, there are times when the engine seems to surge at rates that don't match my desires.
We have heard about the "Limp home" mode that comes into play when the computer or other electronic failure occurs. This LH mode is extremely simple. It's nothing more than a metal tang bent out on the inside of the actuator and this tang will contact the actual throttle plate assembly after you depress the throttle about half-way. When you press the throttle all the way to the floor, you only get about half-throttle. It will "get you home" but it's no way to drive.
What I did was build a spacer inside the housing that takes up most of the distance from the tang to the throttle plate assembly. In this way, my LH mode is now almost exactly in sync with what the computer would be telling the throttle to do.
I have yet to install this ETA with my "improvement", but I will soon and I will post my results (good or bad).
Last edited by ChristianAnarchist; 04-05-2011 at 08:26 AM.