Using only part of the ECU functions

[DRP67207]

Okay, just starting to work through this idea and would like any feedback or insight you all might have.

I am planning to swap a TDI into my mk1 caddy (have yet to pin down a donor, but would like to use an AHU) and am thinking of going mTDI.  However, I would like to maintain the EGR system if possible to help with emissions.  Would it be possible to maintain the ECU and supply it with the signals it needs to determine the EGR valve possition (such as throttle position) while leaving the other sensors and electronics from the eTDI out?  Anyone know if the ECU will give the proper output for EGR control without other signals, or is there some minimum amount of function the ECU needs to put out any signals (if that makes any sense)? Also, what would be the best resource for more fully understanding the ECU wiring and functioning? Do the Bentleys for these TDIs have good info, or are more in depth diagnostic manuals available for these ECUs? 

I'm sorry if the question and my wording is somewhat vague, in the process of getting to know TDIs (been an IDI person up until now) and mulling this over and don't have a specific engine yet to direct my research to, but any thoughts you might have are appreciated. 

Thanks.

[theman53]

 If I understand it correctly, I would think that you could do that, it would continually have codes present I would think. I am not sure, but the guy to ask never gets on anymore, Malone. Maybe send him an email at Malone Tuning and see. If nothing else he usually can mod the ECU to do what you need it to as long as the functions aren't piggybacked together to run multiple things.

[DRP67207]

Thanks for the reply.  Yeah, I need to find some resource that shows what inputs the ECU uses to control what functions, but from my rudimentary understanding and research, it seems like the EGR position is only determined by a few sensor inputs, so hopefully those could work on they're own.  The research continues...

[theman53]

Why are you wanting the EGR?

[DRP67207]

I'd like to keep the EGR for faster warm ups and to help keep emissions down.

[bbob203]

The egr only helps with warm ups on cars with an egr cooler. Keep in mind as well the egr systems on these engines like to get clogged. If you have a properly built and tuned pump your emissions wont be anything to worry about.

[theman53]

If the emissions aren't the biggest issue and you do have it running well the warm up can be addressed in other ways. Block heater is very beneficial so is getting one of the coolant flanges with 3 glow plugs in it to warm the coolant while running.

[bbob203]

I have thought about putting the coolant glowplugs on a switch that somehow shuts off when the coolant reaches a certain temp but I am clueless on how to do it.

[theman53]

crspm5 is an electrical engineer IIRC