Now I’m familiar with engine swaps and where they can be useful, but the idea behind the engine management system throws me off.If for example , I have a stock engine in my 2008 Chevy impala , then I decide to install let’s say a k24a4 into my impala , will I need to get a whole new ecu with the engine management software already installed on it? or can I just install the engine management software on my oem ecu? , and if so where would I even get the engine management software for the engine? and how would I install it on the device?. I have a lot of questions , please try your best I’m just really looking to understand this concept.
There are 3 options:
1) use the ecu matching the engine
2) purchase a third party tuning ecu and get it programmed to suit
3) have a tuning company re-program the existing ecu from the old engine - this may or may not be possible - they will tell you
For all 3 you will probably need the dealer level computer software to code the ecu to the engine and security ie keys etc
1 is likely to be the cheapest but I have no figures for the others - check out the performance tuning companies...
GM engine management software (from your old Impala ECM) is not going to be able to run a Honda engine. If you managed to flash the Honda software onto your GM ECM, you'd likely brick the device.
A Honda ECM - which you'll need to run the new engine - is not going to talk to your BCM. Even if you could get the thing plugged up correctly, which is going to require a ton of electrical work, compensation for missing or extra components, etc., you wouldn't be able to start the car unless the ECM and BCM can talk to each other and are speaking the same language. That is most definitely NOT the case here.
Installing an engine from a different manufacturer is non-trivial. I would not recommend that you attempt this unless you can find a kit for installing this engine in your car that includes all of the necessary electronics, wiring harness, etc., or if you are an electrical and automotive engineer that's done this before, or if you're happy with the car sitting for a year while you figure all of this out.
You need to think about things like O2 sensors vs wideband sensors, ignition coil differences, variable valve timing - Honda and GM's systems are very different.
This is a huge project.