ninja12
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posted September 26, 2006 12:10 PM
Resistor wiring for dry nitrous
I am not a electrical genius!
If you hook a resistor in the orange wire it adds extra fuel depending on the size of the resistor.
The more resistor the more fuel.
IF you hook a wire in parallel to the resistor what would happen?
I ASSUME it would go thru the least resistants, the wire, so no fuel change.
I read somewhere on here that the computer didn't like for you to switch the wires no matter how fast you switched them.
I suggest that we can hook up both wire at the same time and remove the low resistant wire thru a relay when nitrous when is activated.
NO WIRE SWITCHING !! The resistor is still connected .
This simply adds or removes a path of less resistance.
How long do you think it would take the CPU to see the change.
What do you guys think ?
  
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thekaz
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posted September 26, 2006 12:50 PM
 Edited By: thekaz on 26 Sep 2006 13:51
It depends if the signal is digital or not ?
And the ECU is pretty dam fast something alone the lines of a NPN Transistor or MosFet maybe would be fast enough ?
HHHMMMMM need beer to think properly :P
Your talking a resistor in the coolant sensor circuit to trick the ECU into thinking the engine is cold and richen up the mixture RIGHT ?
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ninja12
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posted September 26, 2006 12:56 PM
Yeap.
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wannabe
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posted September 26, 2006 09:05 PM
wiring the resistor in parallel would reduce the overall resistance of the circuit thereby reducing the amount of fuel.
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ridgeracer
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posted September 26, 2006 09:19 PM
Edited By: ridgeracer on 26 Sep 2006 22:21
You may not be an electrical genius but your idea is a sound one. Wired the way you describe there would be no open circuit time. I'm sure that what causes the ECU to fault is detecting that there is an out of range (open circuit) on the coolant sensor circuit. Wired the way you describe you would not need a fast switch, a regular relay would do.
The question is however does the normal coolant sensor resistance increase or decrease with temperature? You would put the resistor in series to increase resistance. You would put it in parallel to decrease resistance. "Hook a resistor into the orange wire..." is not very detailed.
The quickest way to tell would be to unplug the sensor and measure across the sensor when the bike is cold and again when it is warmed up.
Here is a schematic for either option.
http://www.olympus.net/personal/mbially/nitrous.pdf
Of course all bets are off if you hit the 'cold' switch when the bike is cold.
As for reaction time; After looking at the ZX-12 ECU B2 model software my educated guess would be less than one crank revolution. I'll try to look at that code this weekend and see if I can figure out what the allowable limits are.
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thekaz
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posted September 26, 2006 09:33 PM
ridge you beat me to it .......
i am liking this idea .....
who is trying it first ???
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ZXLNT
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posted September 26, 2006 09:42 PM
The resistor trick has been done years ago. ZX12Richard at 12R.org has had the setup for years..
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thekaz
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posted September 26, 2006 09:46 PM
quote:
The resistor trick has been done years ago. ZX12Richard at 12R.org has had the setup for years..
Ya but which of the wiring setups is he using ???
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wannabe
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posted September 26, 2006 09:52 PM
quote:
The resistor trick has been done years ago. ZX12Richard at 12R.org has had the setup for years..
Are you saying that he wired it up with a relay, or are you saying that he just wired the resistor in series with the temp sensor? If it's the second, then that's not what is being described here.
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wannabe
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posted September 26, 2006 10:12 PM
quote:
You may not be an electrical genius but your idea is a sound one. Wired the way you describe there would be no open circuit time. I'm sure that what causes the ECU to fault is detecting that there is an out of range (open circuit) on the coolant sensor circuit. Wired the way you describe you would not need a fast switch, a regular relay would do.
The question is however does the normal coolant sensor resistance increase or decrease with temperature? You would put the resistor in series to increase resistance. You would put it in parallel to decrease resistance. "Hook a resistor into the orange wire..." is not very detailed.
The quickest way to tell would be to unplug the sensor and measure across the sensor when the bike is cold and again when it is warmed up.
Here is a schematic for either option.
http://www.olympus.net/personal/mbially/nitrous.pdf
Of course all bets are off if you hit the 'cold' switch when the bike is cold.
As for reaction time; After looking at the ZX-12 ECU B2 model software my educated guess would be less than one crank revolution. I'll try to look at that code this weekend and see if I can figure out what the allowable limits are.
Thanks for the schematic. I have a couple comments/questions:
1. I thought that the sensor was an intake air temperature sensor not a coolant sensor. It would seem somewhat slow if the ECU used the coolant temperature to tell it whether or not to richen the mixture. (but, I could be wrong.)
2. Regarding the schematics, I am assuming that the resistance increases as the air temperature decreases. Since a higher resistance adds fuel to the mixture, it makes sense that more resistance means colder air. Colder air is more dense thereby needing more fuel. (but, I could be wrong.)
3. Regarding your first schematic (higher resistance when cold), this makes sense based on the original idea, but wiring it this way would require a couple extra steps. Let me try to straighten them out in my head then I'll post them.
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wannabe
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posted September 26, 2006 10:34 PM
OK, I think it's cleared up in my head now. Ninja12's idea is great, but I'm not sure that it will be so easy to impliment. From the old threads, I recall someone saying that a 470 Ohm resistor in series with the sensor richens the map accross the board by about 8%, which is about right for a 40HP shot of nitrous. Here are the issues that I see:
1. If you wire this same resistor in parallel, then the overall circuit resistance is reduced. The map would be leaned out by some unknown amount. I don't know the resistance of the original circuit, so I can't say by how much.
2. When the resistor is wired in series it effectively offsets the map linearly. Basically, it just moves the resistance up a fixed amount at ever temperature. So, that's a fixed amount at the entire temperature range.
3. But, wiring the resistor in parallel also changes the slope of the overall circuit resistance curve. This means that the fuel offset will be different at different air temperatures.
(Please note that my background is in mechanical engineering not electrical, so what I just said may be complete bullshit.)
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zxlnt
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posted September 27, 2006 04:08 AM
Just the simple resistor trick. Use a solid state relay for quicker switching time. Shouldn't be hard at all to wire up..
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ridgeracer
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posted September 27, 2006 06:19 AM
quote:
1. I thought that the sensor was an intake air temperature sensor not a coolant sensor. It would seem somewhat slow if the ECU used the coolant temperature to tell it whether or not to richen the mixture. (but, I could be wrong.)
It was my understanding that it was the coolant sensor because it was measuring the engine temp to see if it was cold. That is was putting the ECU into a cold running enrichment mode like choking a cold carb'd engine.
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ninja12
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posted September 27, 2006 07:01 AM
Ridge, resistance is higher when cold.
The old trick was to add larger and larger resistors until the desired AF was reached
or use a pot.
BTW, you make some pretty pictures.
Took me a minute to figure out what was going on, because I don't read schematics well.The first example is what i had in mind.
If the parallel actuall does lower the resistance we could add another resistor to the
switched resistor (#3) to bring it back to the normal range.
I think I will try it.
But my test will be crude and real world.
Anyone willing to test with ohm meter?
I ASSUME that the initial test can be done with a cold engine with the engine off.
Once the resistance was set it would remain constant.
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wannabe
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posted September 27, 2006 10:04 AM
quote:
If the parallel actuall does lower the resistance we could add another resistor to the
switched resistor (#3) to bring it back to the normal range.
I thought about this last night, but it's not as straight forward as it sounds. Adding a resistor to the switched side of the parallel circuit would really only work for one point. Wiring the other resistor in parallel does two things:
1. Reduces the overall resistance.
2. Reduces the slope of the curve.
What does this mean? It means that even if you compensate for the #1 with an additional resistor at a single data point, at other points, you will still be off with your air/fuel mixture. Since the slope of the curve is lower, you will be too lean at colder conditions.
I'll post the graphs when I get home later today. It will make more sense when I do so.
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thekaz
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posted September 27, 2006 10:07 AM
Hey ridge I got a question for to wrap your head around .....
Wiring the resistor through whatever means cuaseing the actual temp signal to the ECU to be reduced by the the increased resistance.....
On a hot day the total ruduction in signal is the same as on a cold day....
Would it not be better to create an artifical signal to ECU instead of just reducing the existing one ? This signal would then put the ECU into a "open loop mode" no matter what the actual temp of the bike was...
If that sensor is like other automotive one then the ECU is actually looking for a specific voltage that could be faked ?
I was just thinking this morning that if it was hot enough even the added resistor would not reduced the signal enough to make the bike go into "open loop mode"
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ridgeracer
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posted September 27, 2006 10:54 AM
Edited By: ridgeracer on 27 Sep 2006 11:56
quote:
The old trick was to add larger and larger resistors until the desired AF was reached
or use a pot.
They used to cut the orange wire and put a resistor in between the cut ends? They put it in series?
quote:
BTW, you make some pretty pictures.
Here is another one for you.
First I traced out the circuit. It includes an internal 1.8k pullup resistor to 5V that makes a voltage divider with the water temp sensor. Then I looked at the ECU software (for a ZX1200B) to see what it did with the water temp signal.
The voltage is converted to a number. Any voltage of 0.3V or lower becomes value 0. Any voltage higher than 4.7V returns the same value as 4.7V. The value is divided by 8 and you end up with a Temp number between 0 and 29.
Then the software goes into a look up table in the A/F Map and pulls a byte pointed to by the Temp number and saves it as a Injector offset.
The chart above shows the Map data result for normal operation center (maroon color). On the bottor scale (x axis) 1 = 0.3V (112 ohms) 29 = 4.7V (25,300 ohms)
The Map +40 data in front (blue) shows how the internal ECU map data is adjusted if you put a 470 ohm resistor in series with the sensor.
The Map || 470 shows the effect of putting the 470 ohm resistor in parallel with the sensor.
I looked at that data and it seems to me that 1 would be cold, lots of added fuel, then as the engine warms and the sensor resistance increases you quickly reduce the fuel till operating temperature then gradually after that as it heats up.
But now you tell me that the resistance, and therefore the voltage decreases as the bike warms up meaning a cold bike is on the right side of the graph. That would mean a lower value results in a richer mixture.
This is just the raw map data. I have not reached the point of understanding the code to where I can tell you how many milliseconds of injector time plus/minus the values result in. But I thought it was interesting.
Also this is for a ZX1200B2, your mileage may vary
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ridgeracer
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posted September 27, 2006 11:44 AM
Sorry I missed the earlier questions, I forgot to refresh my page before posting....
quote:
I'll post the graphs when I get home later today. It will make more sense when I do so.
Here is some data for you to chew on 
The voltages are the zone boundries the software uses to point to a map value. A voltage < 0.29 returns map temp offset value 1. 0.29 < voltage < 0.45 returns value 2 etc.
The resistance is the value between the ECU temp pin and ground that would give you that voltage.
Volts0 K Ohms
0.29 0.112
0.45 0.178
0.61 0.248
0.76 0.324
0.92 0.405
1.07 0.493
1.23 0.588
1.39 0.691
1.54 0.803
1.70 0.927
1.86 1.062
2.01 1.212
2.17 1.378
2.32 1.564
2.48 1.772
2.64 2.008
2.79 2.278
2.95 2.589
3.11 2.951
3.26 3.378
3.42 3.889
3.57 4.512
3.73 5.289
3.89 6.284
4.04 7.604
4.20 9.439
4.36 12.164
4.51 16.632
4.67 25.306
graphically
quote:
This signal would then put the ECU into a "open loop mode" no matter what the actual temp of the bike was...
If that sensor is like other automotive one then the ECU is actually looking for a specific voltage that could be faked ?
You could do that but are you sure you want to take engine temp totally out of the equation?
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thekaz
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posted September 27, 2006 12:13 PM
quote:
You could do that but are you sure you want to take engine temp totally out of the equation?
Actually the ultimate would be to fake the lowest possible engine temperature that is still high enough for the the ECU to close the loop. That would give you the richest possible mixture with still using data from all the other sensors.
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wannabe
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posted September 27, 2006 04:38 PM
quote:
OK, this is what I was talking about. Notice that the slope of the map with the 470ohm resistor wired in parallel is totally different. You can't fix the problem by just adding another resistor in the switched leg of the circuit.
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tuusinii
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posted September 27, 2006 10:12 PM
Just to note the ECU is always in open loop because there isin't any feedback. And if You think about it, it's better to add only some offset because when the temperature changes the engine needs different amounts of fuel even if there is nitrous there too. But the problem ist that because of nitrous the curce should be different shape than without because the nitrous brings more air to the motor and so the temperature isin't as a big of factor. But when adding only 30-50hp the difference isin't that big because the engine alone makes 160-170 hp so it's only about 25%.
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ninja12
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posted September 28, 2006 06:31 AM
quote:
quote:
The old trick was to add larger and larger resistors until the desired AF was reached
or use a pot.
They used to cut the orange wire and put a resistor in between the cut ends? They put it in series?
.
Yes.
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ridgeracer
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posted September 28, 2006 07:56 AM
Edited By: ridgeracer on 28 Sep 2006 09:07
After doing a little more investigation on how the ECU handles the coolant temp input I now believe the above graph of map data is not an injector offset but actually correction data to compensate for the non-linearity of temp sensor itself. This makes a lot more sense when you look at the curve.
I found that this corrected value is then used to lookup several other map values. These secondary values are all large when the engine is cold and fall off rapidly when the bike warms up which is what you would expect of an injector offset for a cold engine.
On the bottom axis 1 is cold, 255 hot.
As you can see you would have to force the temp signal to the cold quarter of the temp range to have any effect. It also shows it does have some adjustability.
It looks like an active op-amp circuit would be the best way to go. One that would normally follow the sensors output but force the coolant temp signal cold when the nitrous switch was pushed.
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ninja12
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posted September 28, 2006 08:07 AM
Edited By: ninja12 on 28 Sep 2006 09:08
You build it, I will test it with the LM_1.
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ridgeracer
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posted September 28, 2006 11:16 AM
Which would easier to integrate into the existing nitrous system?
Activating by grounding a lead (Switch to Ground)
or
Activating by 12V (Switch to Power)
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