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Stacygifford 05-13-2013 10:29 PM

$10 DIY cylinder management for honda
This will only work if your o2 sensor only reads some of the cylinders

Awesome news ! My DIY cylinder management system actually works!

This is my project thread

Variable displacement experiment. 91 Civic Si B18 - YouTube

The first thing that I did was checked the resistance of my injectors. They were all between 2.4 and 2.6 ohms. (92 - 95 should be around 8 ohms FYI) Being that I could not find any 2.5 Ohm resistors that could handle more than 1/4 watt of power I wired four 1/2 watt 10 Ohm resistors in parallel, which yields a final resistance of 2.5 ohms.

The next thing that I did was remove the plug from injector one and unplugged the two plugs in the wiring harness that go to the injectors. (see next picture)
The green one goes to the resistor box (nonexistent in 92-95 Hondas) the large white plug is where you test what wire goes to where. They are also color coded, I always check with a volt meter to be certain before I go cutting the wiring harness.

To make sure that this would fool the computer, and to prevent myself from wasting a few hours of wire in something that would not work; I simply put the resistor directly on the cut wires and completely bypass the injector.

I went in the car turned the key and to my amazement it started with no check engine light!!!

Granted, it did run a little rough or in just three cylinders Lol..
Now, it was just time to wire it all in!
To make the alternate circuit I used a DPDT switch from radio shack (On-Off-On) I was hoping to find a DPST On-On switch, but it is just as easy to skip the center off position.

On this style switch there are six terminals. The three on the left and the three on the right that are completely independent of one another(one circuit for each injector)

On the upper two terminals I connected the resistors and spliced into the constant power to injectors 1 & 4
The middle terminal I connected to the ecu side of the injector ground wire (brown in the first picture)
And on the lower terminals connected to the injector side of the ground wire (brown in the first picture)
As a side note the wire color for cylinder number four is yellow.

Listed tools and items needed
• Resistors equal to resistance of injectors (2.5 ohm in 88-91 civic 8 ohm in 92-95) ~$4*
NTE HW010-10 - 1/2W 10 Ohm 2% Resistor : Resistors |
8-Ohm Non-Inductive Resistor : Resistors |
• Soldering iron with Solder
• Good wire (12-18 gauge, I used about 30 feet....) ~$6*
• Heat shrink ~$4*
• Wire cutters/ strippers
• 1 DPDT On-Off-On switch (Or a DPST On-On switch) ~$4*
* cost is assumed if buying new.

Most people who do wiring should have all of these with the exception to the switch and possibly resistors, all I purchase were the resistors and the switch.

This will only work if your o2 sensor only reads some of the cylinders

t vago 05-13-2013 11:06 PM

Let's see some fuel economy improvement figures from your cylinder management circuit.

Frank Lee 05-13-2013 11:10 PM

WTH is this?

t vago 05-13-2013 11:19 PM

It's also called "shutting off said fuel injectors" without also "deactivating the related intake and exhaust valves."

Frank Lee 05-13-2013 11:25 PM

It's called not looking at existing data. :/

As if no CEL means it works.

Stacygifford 05-14-2013 12:09 AM

There will be pumping losses, but I will be posting mileage numbers as I get them.

Frank Lee 05-14-2013 02:39 AM

Should probably have done that first.

a8ksh4 05-14-2013 02:57 AM

Hmm... I'll play devils advocate here, probably because I haven't seen the existing data yet, but this makes sense to me. If we're only running on two cylinders, we only make half the power, and can run the motor much closer to WOT for the same fuel consumed and power outputted. This means reduced pumping losses.

Why won't this work? ;)

If this setup alternated between cylinders 1,3 and 2,4 ever few seconds, it could probably lower overall engine temps and reduce cooling needs. I remember reading about how the Cadillac Northstar cars could run w/o any coolant by cycling off 1/2 of the cylinders at a time and using a bit of fuel to cool the ones that weren't firing; sort of a keep-alive mode until the car made it to the next shop.

Frank Lee 05-14-2013 02:59 AM

Just look up the cylinder deactivation threads- they're long and exceedingly involved, why do it all again?

Stacygifford 05-14-2013 10:03 AM


Originally Posted by Frank Lee (Post 371427)
Should probably have done that first.

Sorry, installed everything, drove it, and posted it on here.

a8ksh4, That would be much more involved.. tricking the ecu to say injectors are firing is easy, that would involve fooling the o2 sensor.

I do know that this has been brought up many times before, but I have addressed every problem brought up in other threads. (with the exception of pumping losses) are there any other problem you can think of?

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