Quote:
Originally Posted by justpete
If you pop the pins for the DSC/ABS connection to the DME all the nannies will be defeated as the DSC module ceases to do anything. That's how the shop preps their racecars to have ABS only. No coding necessary other than to turn off the lights on the dash. They'll be doing this to my car before it leaves the shop. FYI
|
have you had this done yet? Is this on an N55? What shop?
I like the idea, but after some testingI doubt it would work without a piggyback ecu.
the DSC/ABS connection to the DME is not a simple connection between the two modules. they are both on the PT-Can bus (PT= Powertrain) with other modules like the combi-dash, HVAC controller, starter controller, etc.
Today I tested some:
disconnecting the ABS/DSC from the PT-Can bus:
a. no speedometer, as there is no wheel speed data from the DSC to the combi
b. lots of warning lights
1. air bag - air bag is dependant on speed/accelrometer data from DSC
2. service - yeah I know something is out of sorts
3. DSC inactive - yeah that's a desired state
4. ABS - Red light - not true, the ABS works fine, but the combi cannot see the module.
c. wipers run constantly- just in case you didn't notice all the lights this will encourage you to go to a dealership or pull the wiper fuse.
d. rev limit around 4500 to 4800 - maybe this is the combi assuming the car is in 6th gear, as there's no speed data to calculate the gear with, and enforcing the top speed limit regardless of the actual gear. Can the top speed limit be coded off?
e. there was however no problem making boost, and the car behaved like an open diff. abs was fine.
Then for an additional test I tried the other side, which is disconnecting the PT-can from the engine. This was no good:
a: no tach or oil temp on the combi
b. no boost -- ? limp or lack of data from? - the boost controlled directly by DME or by another module.
c. starter runs for full 3 seconds, even after engine is running.
d. fan runs on full high - without engine data, assumes it is hot hot
e. AC compressor runs on minimum output, without data assumes it is high rpm.
f. still rev limit around 4500, not sure eaxctly as I have no tach, but I cannot get up to highway speed of 55mph in second gear.
I don't think most of these are issues that can be coded away, as they are mostly caused by lack of data between modules on the PT-bus.
It would be cool if they could be, again let me know the shop.
There may be a sweet spot to splitting the PT-can in to two, where the DSC and the engine are isolated, and the engine has access to the modules it needs, while the DSC is alone.
obviously a piggyback tune could avoid some of the issues.
I'm curious what that shop is doing, and if it is on N55's. Let me know I'd like to believe.