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Old 04-24-2008, 09:29 PM   #1
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DIY displacement on demand system project

Thoughts and feedback welcome on the following scheme:
Engine: 1994 Toyota Camry 3VZ-FE CAT (3L V6 non-VVT-I)
Transmission: 4-speed automatic FWD transaxle with lock-up Torque Converter
Odometer: 340,000Km
Fuel injection system: Sequential multi-point fuel injection EFI
Oxygen sensors: 3 total: 1 on each engine exhaust manifold and 1 sub-oxygen sensor mounted downstream of the Catalytic converter (CAT)
Firing order: 1-2-3-4-5-6
Current average fuel economy: 10L/100Km
The plan:
Through testing of the engine I have found that it still runs reasonably well on 3 or 4 cylinders for cruising.
I intend to have three modes of operation:
Normal (all 6) for start-up, warm-up and acceleration
V4 (4 cylinders) for high-speed cruising
I3 (3 cylinders) for low-speed cruising.
For 3 cylinder mode I will deactivate cylinders 2, 4 and 6 (the front bank) and for 4 cylinder mode I will deactivate cylinders 2 and 6. I have found these configurations the smoothest.
I also intend to deactivate the oxygen sensor for the disabled bank and the sub-oxygen sensor. The sensor for the running bank (cylinders 1, 3 and 5) will remain untouched.
The reason for this is it will either:
A: trick the control computer (ECU) into thinking everything?s normal and not just dumping more fuel into compensate, negating any economy gains; or
B: put the ECU into ?Limp-home mode?, which will cause the ECM to substitute pre-programmed values for the turned-off sensors, which since my engine is well maintained should run like normal when at operating temperature.
The method by which I will deactivate the cylinders/oxygen sensors is by rigging up a bank of centre-console switches to turn off power to the appropriate fuel injectors and Oxygen sensors.
The intake and exhaust valves will not be deactivated so the deactivated cylinders will act like air pumps.
The idea is to rig everything up and then do fuel economy tests in various modes to find out what effect it has on fuel economy. But before I do I want to make sure the engine will handle everything (i.e. by not blowing up), both short and long term, so would like opinions/constructive abuse on whether it?s a good idea.
Potential worries to consider:
-uneven wear
-uneven cooling
-deactivated cylinders not being lubricated properly
-burning intakes valves due to no cooling fuel passing over them
-extra oil consumption due to lack of sealing pressure on deactivated piston rings
-shorting or arching when flicking the switches, at best blown fuse, at worst blown ECU
-mechanical failure of connecting rods, pistons, bearings, engine mounts
-Fuel economy gains offset by engine overcoming pumping losses

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Old 04-25-2008, 04:28 AM   #2
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You don't need to post the same thing in two different sub-forums.
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