ECT mod

[Darren]

I am doing the ECT mod and have a question regarding the pot.

 I soldered the resistors to the leads on the pot as it says in the directions. Do I now solder a wire on each of these leads and connect at the first cut I made on the green/black wire and one at the end? Does it matter where they are attached?

Thanks in advance for your help.

Darren

[John U.]

On my Standard I spliced the Pot into the green/blue wire, the color could be different on an I/S. Picture # 1 in the ECT mod instructions shows the 3.9Kohm resistor spliced into the green/blue wire; that is where the Pot goes. If not using a Pot then the resistor goes there.

[Friagabi]

I ride a 2KIS so all colors are for that model. Check Chet's wiring in Shop Talk for your colors.

The goal of this change is to tell the engine control module that the engine is cold when it is actually hot.

The control module does this by looking into the engine coolant tempature sensor and reading it's resistance.

Factory says that when the engine is 68' the resistance will be between 2000 and 3000 ohms

Factory says that when the engine is at 176' the resistance will be between 200 and 400 ohms

The module looks into this circuit from under the seat behind the overflow tank. So, adding resistance or reducing resistance anywhere from the module to the sensor will do the trick. So will a broken wire anywhere along this route.

So if putting the pot in the neck cover is a hard place to reach you can find the same wire at the engine control module and mount the pot closer to the seat. If you solder the connections you can mount the control on the handle bars or anywhere else you want.

The sensor has two wires going to it. We will talk about the ground wire first. Mine is Green/Black it also serves for the ground for the ign sensors. This circuit should be left intact. It is in fact a ground but it is bonded to the control module. Another way to say this is that this ground is dedicated to the engine control module. It is the basis for the ground the control module uses. If you cut it and do not solider the connection together when you repair it you can introduce some unusual problems with the engine control module.

The other wire is the wire that the control module looks into to read the resistance of the coolant sensor. This is the wire that we want to change the resistance of. on my bike it is Pink/White

Never put 12 volts on either of these two wires. If you happen to ground the Pink/White wire the module will think that the engine is real cold.

When I first did this change I had a question, did the module see the resistance as a changing smooth ramp or was the mapping of the module a saw tooth ramp. The answer is that the module sees a ramp of smooth resistance increase or decrease. As you change the resistance the module also smoothly changes the ign advance. At least within the mapping that the factory built in.

The graphs of the factory module (both hot and cold) used to be on the aftermarket engine control module site.

Back to what is going on with the pot as installed into the sensor circuit. When the engine is hot the engine control module retards the ign timing. If you lie to the module it will advance the ign timing thinking that the engine is cold.

When the engine is cold the resistance of the sensor is 2 to 3 thousand ohms. If you want to lie to the engine control module and tell it that the engine is cold all that you have to do is add a 3.3K ohm resistor from radio shack and the control module will advance the ign timing as far as the factory will allow.

If you want to adjust the timing then use a pot instead of the fixed resistor. Half of the resistance is not actually half of the advance. I would reccomend that you pull the inspection cover in the center of the tming belt cover and use a timing light to watch the marks while you decide just where the timing is going when you twist the knob.

When I first did this mod I passed on the pot. Instead I used two fixed resistors, two relays, two toggle switches, and indcator LED's so I could tell when I asked for half of the advancement or the full advancement on a hot engine.

If I were to do it again I would use one toggle switch and one resistor. Either a factory setting or the full advancement allowed. Simple, easy and repeatable. and I would have cut into the harness close the the engine control module so the switch could be between my legs. Easy to reach and operate.

Hope this helps.

[Friagabi]

Sorrry, I forgot to comment on the diode. It's purpose is to cancel the addded resistance when you shift into neutral. The outcome of this is that the increased idle speed can be cancelled by shifting into neutral. Nice feature if you are sitting at a long red light.

On the other hand if you mount the switch on the right side of the bike all you have to do to control the increased idle is to flip the switch with your right hand while holding in the cluch with your left hand. As I almost always leave the mod engaged at full advancement It was just added hassle to go bad. Or install incorrectly.

[Friagabi]

Yes, it does make a difference. If you have cut into the ground wire, be sure to do it on the sensor side of the plug found in the neck of the bike (the two wire plug). That way you are less likely to have a floating ground above where it is supposed to be except at the sensor and the sensor does not care. Which end of the pot you hook to which end of the cut is not important. But if you are using the diode it does make a dfference which wire of the diode you hook to the sensor circuit and which end you hook to the neutral circuit. It also makes a difference which side of the cut you hook the diode to.

[Darren]

Thanks. Can I assume I did the mod correctly if when I am in gear  and turn the pot my RPM's increase by about 200?

[Friagabi]

If he engine is ho hat is exactly what should happen, If you have used the diode then crank up the pot and shift into neutral and he idle should drop back doen, shif it back int gear and the idle should pick up again. If it does not then you may have the diode in backwards.

[John U.]

Posted by Friagabi: "If you want to adjust the timing then use a pot instead of the fixed resistor. Half of the resistance is not actually half of the advance. I would reccomend that you pull the inspection cover in the center of the tming belt cover and use a timing light to watch the marks while you decide just where the timing is going when you twist the knob."

Friagabi, is the amount of advance proportional to the increase in idle speed. I've been assuming that it is, but I've never checked, thought you might know.
TIA, John

[Friagabi]

Great question, I do not have the answer. When I had the timing light on the girl and was watching it move by he pot I was after the resistance for 1/2 advance and complete advance.  It never crossed my mind to check the scale of movement as I was already decided not to use the pot. Either by roation of the knob or increase in idle.

I can say that if you use a audio taper pot it is not 1/2 the resistance at half rotation, that is why it is called a audio taper.

I would guess that RPM increase would be a better indication of 1/2 advancement. At least for every day use. Although Honda does some factory tuning that I never saw in American built cars until the last few years. This is not what you would call high level tuning. We are only messing with the advancement up to around 3500 to 4000 RPM and then it reverts to factory tuning. On crank over to start it also uses factory tuning for a cold engine. If I remember correctly the graphs don't start to change untill 1000 to 1250 RPM.

Simple rule is to apply all of the advance available, DO NOT LUG THE ENGINE UNDER LOAD keep it running free so not to cause it to ping. If all that you are going to play with is timing then this mod will supply all of the snap that this engine can deliver between these RPM limits.

If you worry about ping then move up one grade of fuel. I used to worry about this (was I hearing pair valve click or ping) well it finally digested some fuel on the gulf coast (mosly water? or laced with either) anyway it pinged. You will know if this engine is pinging (so will the driver in the next car).

My IS is just fine with full advancement or in the worst case no advancement. Now that I pull my house behind me I run with it off around towns or pulling a hard hill.

I think you will find that this engine will perform up to about 28' of advancement without problems and a little common care from the driver. You won't push this limit with this mod.

If you are doing this mod then you are not the average driver Honda designed this bike for. If you are doing this mod and do not understand why then you better learn what you just did to your engine or think about always buying hi-test fuel or go back to a hot bike that burns regular fuel.

I like the gain off the line and do not worry about buying higher octane fuel. And the real cool thing is that I can turn it off to detune the engine for regular fuel. Best of both worlds. You will have to be the judge about an adjustable advance within the available range.

Best bang for the buck and that don't happen offten.