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This will not be 100% comprehensive but will be related primarily to tuning as it affects things like supporting mods, manual swaps, and the like.
First thing to understand is that there are 3 versions of ME7 used in Volvo turbocharged models from 1999-2009. The first version was used on 1999-2000 models and was not a full can bus network as the later 2001 models were.This means the potential to manual swap these cars is much easier as you only have a few modules that are impacted by a removed TCU. The second version of ME7 was 2001-2004 and was twice the file size but not too much more complex. These ECU's were on a full CAN bus network where all the modules talk to each other, unlike earlier models where the only network communication was between the ECU, TCU, ABS, Immo, and CDM (instrument cluster).
In 2005 the latest version of ME7 came out and while there were some differences in comparison to the 2001-2004 ECU's the main difference was the communication speed which jumped up from 250kbps to 500kbps.
Internal control strategy:
First thing to understand is that ME7 is vastly different than M4.x fuel systems used from 1994-1998. The main difference for the performance enthusiast will of course be around boost development and control. Where M4.x did not have a boost sensor to read actual boost value ME7 does. The boost pressure sensor in ME7 however actually has little to do with how boost is developed but is more of a safety catch if boost goes too high or is significantly too low.
ME7 is a torque based system, meaning that when you depress the throttle 50% you are effectively asking ME7 to give you 50% of the torque the ECU is programmed to allow. At 100% throttle you are effectively asking the ECU to give you 100% of the torque the ECU is programmed to allow. Notice I said "asking the ECU". That's exactly what you're doing because even though you might ask for 100% torque, the ECU may not allow it. Reasons for this can be things like overheating engine, traction control has messages that there isn't sufficient traction to suppor the user torque request, CEL on for misfires, etc...
As it relates to expected boost values:
Since ME7 is only concerned with the power (torque) it is being asked to provide it could just about care less about boost. For instance, if a particular ME7 ECU were programmed for a max torque allowance of 280ft/lbs and the user throttle request was at 100% then ME7 would try to provide that full 280ft/lbs if conditions allowed (i.e. no loss of traction, no overheating, no CEL, etc..)
If by chance it was a cold day and environmental conditions were optimal it may only require 16psi to develop that torque value. However if it were a hot day and environmental factors were not in your favor it might require 18psi to deliver the 280ft/lbs of allowable torque. If the max boost limit programmed in the ECU was 16 psi then even though you were making max boost you might not be making total allowable power. This is why boost target on ME7 may seem low even though the car ECU is providing what it is programmed to provide and consequently can mean full boost isn't necessarily making full power. This is where a datalogger comes in very handy, I've used the bluetooth OBDII loggers with the Torque Pro app and it's surpisingly useful. Scangauge II is also a great product since you can program your own PID's into the Xgauges if you like. I've gotten a few requests on PID info so go here to get the ones you may want: http://en.wikipedia....iki/OBD-II_PIDs
As it relates to ME7 and manual swap. Unfortunately it's not as easy as M4.x but it can be done.
The main complication comes from the nature of how the CAN bus system works. If the TCU is removed then other modules in the CAN network that rely on TCU data may loose some functionality.
For instance cruise control. As the TCU is controlling the trans it constantly sends out info on the can network, things like trans speed, current gear selection, errors, etc.. if the TCU is removed then it's likely the cruise control won't work as other modules in the system that rely on TCU data are expecting a TCU to be there and it's not... they are unable to carry out their functions without the TCU data they've been programmed to use.
Now programming the ECU to be a manual is no problem, so long as we have the original ECU in hand. The ECU will not be relying on the TCU input so it effectively ignores it and wont' trip the CEL.
Other modules in the network will have codes for missing TCU communication but will not cause the CEL to be lit.
Additional complications: The reverse lights might not work, IIRC the Park/Nuetral switch is connected to the TCU so when you put the car into reverse with a manual trans the message normally sent to the REM to turn on the reverse lights will not be there and they wont come on. Of course you can hardwire the lights, but again this is just an example of the few issues that will need to be addressed.
The cost to develop and recode all the modules on the high speed network is unrealistic and you'd be better off sourcing all the related modules (CEM, ETM, ECU, ABS, IMMO, Keys, ETC...) from a junk yard as some have done.
As it relates to Immo and ME7:
As there are different versions of ME7 there are different version of the immobilizer system.
In the earlier 1999-2000 models the system is more simple and the IMMO communicates directly with the ECU. If the key code pin stored in the IMMO matches the key code pin stored on the ECU then the car will start, if the code is mismatched then the car will not start. For these earlier cars manual swaps are easier because you can simply source the ECM, Immo, keys/tumbler, and ETM from a similar model that was factory manual trans and swap them to your car. Pretty easy.
For later ME7 (2001 and on) the Immo is also part of the CEM. The CEM compares the stored key code pin to the key inserted and communicates with the ECU to determined if the start is authorized or not.
The key code pin stored in the ECU is stored on a seperate chip on the board and is not part of the calibration file that makes up the tune maps in the ECU. This chip can be read and re-programmed so you can "clone" as many ECU's for your car as you like. However at this time I can only read and clone ECU's here at the shop, I have not fully decoded the communication sequence to read it through the CAN bus lines. If we can decode the comm sequence this will make ME7 ECU's as interchangeable as the M4.x ECU's.
At this time I am taking on ME7 tuning for 1999-2000 models locally or by mail. Please PM or email me (ardideas@gmail.com) for more info.
If there's any questions just post up!
Thanks guys!
Edited by ARD - Lucky, 17 January 2012 - 09:16 PM.
