Quote:
Originally Posted by dfeldt91
I have been dissecting the ECU code for my 2001 Volkswagen Passat for a while now and am going to start a new project.
I am going to rewrite the ECU to turn my 4 cylinder 1.8 turbo motor into a 2 cylinder .9 liter turbo motor. I tried removing coilpacks and unplugging the fuel injectors for the third and fourth cylinders on another Passat I had but it ran really rough and wasn't drivable.
I am going to rewrite the software to ignore the O2 sensor, change the boost tables, write out two of the fuel injectors, write out the knock sensors and tell the ECU to ignore the misfires it will detect.
I am going to get the camshafts ground down for the extra cylinders, remove the valves and weld closed the hole, then modify the intake manifold so it does not have a passage to the cylinders. I'll also have to weld together a new exhaust system that only receives exhaust from two working cylinders with the nonworking cylinders being essentially open to suck in and push the air out of the exhaust side.
Has anyone done this before successfully? Either mechanically or using modified software as I am doing?
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I see a number of holes in what you are planning:
Firstly you need to kill off cylinders that are firing 360 degrees apart. This means either 2&3 or 1&4 based on a normal inline 4 cylinder. This will ensure that the engine fires evenly.
Secondly, there will be a huge amount of remapping required to get the engine running correctly because of the changed intake and exhaust flow dynamics.
Thirdly, the turbo will be way too big as you have halved the engine displacement. This will mean staff all boost till you rev the guts out of it.
Welding up manifolds will achieve nothing on the intake side. On the exhaust side, leaving the ports open will cause these cylinders to run stone cold and potentially cause large amounts of distortion in the block and head as well as wasting lots of heat that will require fuel to be burnt to keep the engine at temperature.
Removing the oxygen sensor will cause the engine to run in open loop, again wasting fuel and polluting much more.
If you are really wanting to reduce fuel consumption, consider keeping the engine operating mechanically as it should and look at how Toyota has used the Atkinson cycle - mod the cam timing on the intake side, up the compression and possible reduce the stroke by swapping in a shorter stroke crank.
I would suggest looking at newer, smaller VW petrol engines that can be swapped in as a better platform for tinkering.
Simon