Quote:
Originally Posted by Tygen1
I set up some switches to control my shift solenoids. If I start to use them, I need to keep using them until I turn off the car because the PCM forces limp mode. Essentially I am cutting off the PCM's comunication and just sending twelve volts to what ever solenoids need to be active for each gear change. What I found is that the pcm's shifting was pretty much the most effcient for my car. Now if I could lock the TCC in second gear then I could probably improve over the stock pcm shifting, however my TCC is not very robust and it's too much of a risk because I'd have to accelerate pretty briskly to take advantage of the locked TCC which could kill it.
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I'm beginning to think about designing a whole transmisson control unit based around the PIC.. have it do all my shifts etc. The more I read and research the more I realise I'm simply not going to get this no to throw a code, and the one it will throw (P0700) causes a limp mode where it won't change gear any more, it will clear if you swithch off the car and switch it on again.
What I've realised by reading and experiment is this:
ABS system has wheel sensors in.. this gives the car knowledge about the wheel speed.
N2 & N3 speed sensors in the gear box tell me about the internal speeds of two of the planetary gears, not the speeds either side of the torque converter.
The way the TCM works out if the TCC is on/off/slipping a bit is by conparing the wheel speed, selected gear and the engine speed. For which is makes use of the CAM-BUS. (serial, vehicle wide, communication bus)
In other words to fake the correct signals I need to fake the CAM-BUS.
The biggest problem there is that no manufacturer releases this kind of information. There are some codes they release for fault diagnosis, but not enough detail for someone to design their own system. I'd need to do it by measuring each code... but with a vehicle wide serial bus there will be a lot of codes that are seen but don't have any relevance to the TCM.
Best solution is homebrew TCM.. but then I still need it to listen to at least some of the CAM signals. Mainly because the gear selector talks to the TCU over the CAM-BUS (it's tiptronic). I could also do with reading the throttle and engine speed, so I can then make sure that if I lock the TCC I can unlock if my right foot becomes a little heavy.
Derek