|
I was able to make some brilliant deductions today about my transmission. I have concluded that the main problem is indeed the rear axle ratio. This is base on the testing I performed today, deciphering of German Hieroglyphics (Gang means 4th gear as in all gears turn as one big gang).
Therefore error code 147 "Gang not plausible or gearbox slipping". If you ask yourself the only way the GB can know that it is slipping in forth is with an input to output speed comparison since the only two internal speed sensors are n2 and n3. Turbine or input speed can be derived from n2 and n3 but output speed will require an external sensor the wheel speed sensors. Knowing that to do this, the wheel speed sensors must go through a known and fixed ratio it can be concluded that the rear axle ratio is constant withing the EGS module. This also became clear when it was observed that the error would only get set once the car reached 4th gear. I was able to get the car into 4th for a second and then it reverted right to third limp home. From that point on the code 147 would be set. Driving the car in 3rd never allows the car to shift into 4th or 5th and therefore never gives the computer a chance to do a check on gang. The end result is I can drive all day in 3rd and have enough transmission to run a full 1/4 mile at maximum performance with the 2:47 rear. So what that means is I now have a drivable car with a top speed of ~ 125MPH and I will probably increase my fuel consumption to that of a stock 560SL.
So the options.
1) See if the EGS can be reprogrammed. I know a guy with the SDS but he has never done this.
2) Modify subframe to fit the SL600 rear end
3) Purchase a stand alone Transmission Control Module one where I get to write the code.
Option #2 is the best idea and is a long term goal anyway. I have confidence that the 560SL rear is strong enough for the stock M120 engine but it leaves little margin. The SL600 rear is the way to go.
Option #3 is also a long term goal and will in the end keep me from being married to MB
Option #1 is a cheap and quick solution and if it works I will have it done within a week or two.
The one thing I don't have an answer for is that the transmission tends to grown under low speed high acceleration. It still may be slipping. It's nothing really serious but my trained ear knows. This is an early 96 722.6 which is known to be problematic.
The bottom line is the car is 100% under control and drivable. But I started to realize this week I need to connect my heater.
|