Gear ratio help: P0730 code after swapping to a C32 diff - PeachParts Mercedes-Benz Forum

pshek · #1 12-16-2007, 05:26 PM

For the past 2 months I have had an incorrect gear ratio code after swapping my 2003 W203 C320 diff to a C32 3.07 diff. My car used to have a 3.27 gear ratio in the stock transfer case, but I wanted a Quaife LSD, so I bought the larger C32 differential and had a Quaife LSD installed into it. Quaife only makes a LSD for the 210 and 215 units, they do not make a LSD for my smaller stock transfer case. We were able to get the C32 differential to work and fit mechanically. However, the TCM sees the difference in transmission and wheel speed and puts the car into limp mode. Also, I have a C32 motor and ME unit which has been working fine for a year with ESP disabled. I sent my ME unit and a new C32 TCM to Evotech in Germany to see if they can reprogram the modules to accept the gear ratio change, but their efforts did not fix the problem.

The way I see it, reprogramming the modules for the new gear ratio did not work. My only other options are:

1. Find an appropriately sized 3.27 gear set to fit on my Quaife LSD 210 carrier, and remove the 3.07 ring and pinion gears.
2. Modify the rear wheel speed sensor by making a new reluctor ring that will fake the TCM into thinking it has 3.27 gears, ie make a spoofed VSS reluctor ring.
3. Put my old smaller 3.27 open differential unit back in.

I would hate to give up at this point and replace the stock diff. If anybody knows the part # for a set of 3.27 ring and pinion gears that would fit my 210 Quaife unit, please help me out. Any other advice would be appreciated since I'm not sure what else I can do to get rid of this code. I registered with startekinfo.com, but I am having trouble in finding this part.

Peter

C32AMG · #2 12-16-2007, 07:01 PM

Quote:

Originally Posted by pshek

For the past 2 months I have had an incorrect gear ratio code after swapping my 2003 W203 C320 diff to a C32 3.07 diff. My car used to have a 3.27 gear ratio in the stock transfer case, but I wanted a Quaife LSD, so I bought the larger C32 differential and had a Quaife LSD installed into it. Quaife only makes a LSD for the 210 and 215 units, they do not make a LSD for my smaller stock transfer case. We were able to get the C32 differential to work and fit mechanically. However, the TCM sees the difference in transmission and wheel speed and puts the car into limp mode. Also, I have a C32 motor and ME unit which has been working fine for a year with ESP disabled. I sent my ME unit and a new C32 TCM to Evotech in Germany to see if they can reprogram the modules to accept the gear ratio change, but their efforts did not fix the problem.

The way I see it, reprogramming the modules for the new gear ratio did not work. My only other options are:

1. Find an appropriately sized 3.27 gear set to fit on my Quaife LSD 210 carrier, and remove the 3.07 ring and pinion gears.
2. Modify the rear wheel speed sensor by making a new reluctor ring that will fake the TCM into thinking it has 3.27 gears, ie make a spoofed VSS reluctor ring.
3. Put my old smaller 3.27 open differential unit back in.

I would hate to give up at this point and replace the stock diff. If anybody knows the part # for a set of 3.27 ring and pinion gears that would fit my 210 Quaife unit, please help me out. Any other advice would be appreciated since I'm not sure what else I can do to get rid of this code. I registered with startekinfo.com, but I am having trouble in finding this part.

Peter

Engine control modules are version coded with the Differential gear ratios. Did you send Evotech your C320 MODULES, TCM and ME; did you deal with them directly or use a Tuner, coding should have solved this problem.

C32AMG rear 3.27 Ratio: A 210 350 44 39, Use the C32 VIN number to confirm, before you purchase any parts.

pshek · #3 12-16-2007, 10:35 PM

Quote:

Originally Posted by C32AMG

Engine control modules are version coded with the Differential gear ratios. Did you send Evotech your C320 MODULES, TCM and ME; did you deal with them directly or use a Tuner, coding should have solved this problem.

C32AMG rear 3.27 Ratio: A 210 350 44 39, Use the C32 VIN number to confirm, before you purchase any parts.

I sent Evotech my C32 ME 2.81 unit (which supposedly is already set to 3.06 ratio), a new C32 TCM, and my old C320 TCM. They said they just renewed the oem software on the modules, which did not fix the problem. I used the tuner company EuroElites and dealt with Adam G., who is the Evotech North America representative.

What I'm confused about is if my ME unit was already coded for a 3.06 ratio, and I had a 3.27 ratio in the old unit which ran fine, which component was modified to get it running with the 3.27 gearset? Could it be possible that the sensors were reprogramed?

Is this part (A 210 350 44 39) the 3.27 gearset that will fit on a C32 diff?

Thanks for the help.

C32AMG · #4 12-17-2007, 09:35 PM

Quote:

Originally Posted by pshek

I sent Evotech my C32 ME 2.81 unit (which supposedly is already set to 3.06 ratio), a new C32 TCM, and my old C320 TCM. They said they just renewed the oem software on the modules, which did not fix the problem. I used the tuner company EuroElites and dealt with Adam G., who is the Evotech North America representative.

What I'm confused about is if my ME unit was already coded for a 3.06 ratio, and I had a 3.27 ratio in the old unit which ran fine, which component was modified to get it running with the 3.27 gearset? Could it be possible that the sensors were reprogramed?

Is this part (A 210 350 44 39) the 3.27 gearset that will fit on a C32 diff?

Thanks for the help.

I would install the original TCM (C320) into the car, clear all codes from all modules and drive until the transmission is in limp mode. Scan all modules (with a capable scanner) for any codes, and post them.

Gear ratio codes can set for many reasons, wrong planetary gears and differential ratios, transmission slip, wrong TCM/ECM, lose transmission reluctor and defective sensors.

That Part number is for C3AMG 203.265

pshek · #5 12-18-2007, 04:36 PM

I believe that the only code we saw was the P0730 code.

Can someone explain why I had a difference between the speedometer MPH and the digital MPH shown in the MFD panel after the C32 engine swap was completed? The digital MPH is always 20mph slower than the actual cruising speed. So lets say I'm doing 65mph, the digital display shows ~40mph. Why the discrepancy? Was the speedometer recalibrated or are the sensors off?

I believe that the original tech who did the coding must have run into this P0730 code problem when the motor was installed since a C320 has a 3.27 ratio and a C32 has a 3.06 ratio. What he did to alleviate this problem is unknown to me.

All I know is that ESP was disabled in the process, either deliberately or not. The car is definitely more fun to drive without ESP, except in the rain.

manny · #6 12-18-2007, 05:37 PM

going by your description, you have a 10% difference in actual gear ratio, yet an almost 40 % difference in measured speed.
Something is amiss,.......just don't know what.

gsxr · #7 12-18-2007, 05:57 PM

Quote:

Originally Posted by pshek

Is this part (A 210 350 44 39) the 3.27 gearset that will fit on a C32 diff?

I can't confirm that p/n 210-350-44-39 is a 210mm ring & pinion, but I think it is... the EPC isn't very clear on what exactly that will interchange with.

I am still convinced that your problem needs to be fixed with electronics, not gear swaps. As Manny mentioned, if the actual and indicated speeds are not off by the same amount as the ratio change, something is definitely hosed up in the computers.

mbdoc · #8 12-17-2007, 08:08 AM

To start with that code is refering to an internal transmission speed sensor code.

To make a good diagnosis you need to have trans computer coder read. Then procede.

The "conductor" plate in the trans that houses that sensor is a HIGH fail part.