Keeping my 65 in 3rd for the dyno???
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Senior Member
Joined: May 2008
Posts: 445
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From: USA
2018 S63, lowered
Keeping my 65 in 3rd for the dyno???
Last time I dynoed my car we were unable to keep the car in 3rd for the entire pull.....even when in manual mode. The car would continually downshift into 2nd if you weren't high enough into the RPM's, and then back into 3rd, then 4th......is there anyway to keep this thing in 3rd?? I've got the W220 S65, FWIW.
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Joined: Nov 2003
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From: Mechanicsville, VA
'09 CLK550, '18 AMG GTR, '06 C55 AMG, '25 GLS450, 09 E63
You are experiencing exactly the same scenario as anyone that has tried to dyno a V12 TT car whether it is a 600 or 65 series. Even in "M" mode the car will downshift on the rollers into 2nd gear screwing up the run. The only proven way to get the car to not do this is to gently get the car around 3500 rpm or so in 3rd before you put the accelerator to WOT. If you do it any eariler then the car will downshift. It would be nice to see the early part of the torque/hp curve but it just doesn't work on our cars. Maybe Renntech or Kleemann can give you some pointers if you call them. I called Renntech when my car was on the dyno because I couldn't find an RPM lead anywhere and they told me that without an optical sensor on the crank it was next to impossible. Some cars can get a signal from the ECM on a couple wires that they had me check with the inductive pickup on a dynojet with no luck. He said that a few cars had a signal strong enough to read rpm at the ECM. Some newer model dynos actually have a plug for the OBDII port inside the car which has rpm right there. Since our cars have a coil on plug design with no spark plug wires this prevents a hookup there as well. The V-8 compressor cars are easy to dyno and have typical hookups. I wish you luck as this is a frustrating issue with our cars. Let us know if you find out something more or some sneaky new trick.
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Joined: Mar 2005
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From: Long Island, NY
W220 S65 AMG
Finding an RPM lead has always been an issue... but as suggested above, you need some reflective tape on the crank pulley and an optical pickup sensor to read it.
I recommend pulling off the plastic under body panels off before going to the dyno shop, saving yourself time and money.
I recommend pulling off the plastic under body panels off before going to the dyno shop, saving yourself time and money.
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Joined: Mar 2006
Posts: 514
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From: Chicago
CL65
You are experiencing exactly the same scenario as anyone that has tried to dyno a V12 TT car whether it is a 600 or 65 series. Even in "M" mode the car will downshift on the rollers into 2nd gear screwing up the run. The only proven way to get the car to not do this is to gently get the car around 3500 rpm or so in 3rd before you put the accelerator to WOT. If you do it any eariler then the car will downshift. It would be nice to see the early part of the torque/hp curve but it just doesn't work on our cars. Maybe Renntech or Kleemann can give you some pointers if you call them. I called Renntech when my car was on the dyno because I couldn't find an RPM lead anywhere and they told me that without an optical sensor on the crank it was next to impossible. Some cars can get a signal from the ECM on a couple wires that they had me check with the inductive pickup on a dynojet with no luck. He said that a few cars had a signal strong enough to read rpm at the ECM. Some newer model dynos actually have a plug for the OBDII port inside the car which has rpm right there. Since our cars have a coil on plug design with no spark plug wires this prevents a hookup there as well. The V-8 compressor cars are easy to dyno and have typical hookups. I wish you luck as this is a frustrating issue with our cars. Let us know if you find out something more or some sneaky new trick.
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From: In a box
W211 E55
We were able to pick up a signal from the #1 injector harness. Also, if you push the pedal down to the floor without depressing the kickdown switch at the bottom of the pedal, you should be able to get her to pull from a low rpm without having a downshift. You will need a skilled dyno operator though.
It takes a bit of practice, as well as a feel for the car. I have a hard time getting a pull below 2500 RPM.
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Joined: Mar 2006
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From: Chicago
CL65
