Tuning the RX4's Fuel Injection

Working_ZS · 08-01-2021, 01:34 PM

Over in the RX3 subforum, user Lukas has made considerable progress in accessing and modifying the Delphi ECU's fuel injection map. For those interested, the thread is here:

http://www.chinariders.net/showthrea...d=1#post364185

Hopefully much, if not all of what he learns can be applied to the RX4's ECU for modifying its fuel injection mapping as well. There are definitely one or two areas where I would like for the RX4's fueling to be improved, with the light throttle, low speed stuff being at the top of my list.

Bob Kelly · 04-07-2022, 06:32 PM

Agreed I am also unhappy with the way my bike idles and the power just above idle
...as it is way way too lean !...
as with any F.I. system they always tune for economy and emission control not performance..... and I would be very interested on how to change that... the bike needs it !
....
Bob.......

Boatguy · 04-07-2022, 06:46 PM

Just an idea outside the box. I remember there was a thread on here about my type of bike. Not the same thing at all. However, somebody was able to turn a screw on the air intake to adjust it so that the EFI tendency to run way too lean at idle was improved.

JFOlivier · 04-07-2022, 08:04 PM

I read that posting from Lukas and found it interesting, I have a Lifan expect and would like to learn more about the ECU system so will try to get the hardware from Amazon. The first problem is that Lifan has their own ECU which is a Hunier EFI 9.0 whereas the other China bikes use the Delphi and the port plugs are not compatible. I have downloaded ECU Hacker and when I get the cables from Amazon I will have a stab at printing a plug to fit the Hunier plug but don't really know if the ECU Hacker will recognize tis ECU.

Bob Kelly · 04-19-2022, 06:20 AM

Quote:

Originally Posted by Boatguy

Just an idea outside the box. I remember there was a thread on here about my type of bike. Not the same thing at all. However, somebody was able to turn a screw on the air intake to adjust it so that the EFI tendency to run way too lean at idle was improved.

...
thank you for that ! ....I haven't even seen a screw in there but I know there's gott'a be one somewhere ! LOL
I have to pull the rear shock soon so I will look into it then when I have it in the tiny shop... right now it's under it's cover being rained on and the occasional snow thrown in for good measure !
... part of the problem with the RX4 is getting all the stuff off of it so you can find the bike.... the valve adjustment is a snap once you get down to it.... but it'a a 2 hr job to get to that point ! .... reminds me of a Kawasaki Ninja !
you can't even SEE the carbs on my little 250R you have to pull the fairings to find them !
I guess most of the bikes are going that way though...personally I liked the old style where the headlight was attached to the front forks you could see around corners better at night ! oh well..... that's progress for ya !
....
Bob.....

pyoungbl · 04-19-2022, 10:42 AM

The RX4 has a throttle body with a stepper motor to control idle speed by adjusting air bleed to the engine. There is no screw adjustment anywhere on the assembly. Some riders try to fool the ECU into thinking that the engine is running colder than the actual temp, just getting the ECU to inject more fuel. This 'fooler' is just an electrical resistor. Such a mod runs the real risk of over fueling across the board, washing the cylinders of oil needed for lube, and engine failure.

I just verified the lack of a screw by looking at the spare TB I have in my shop.

Boatguy · 04-19-2022, 12:20 PM

Quote:

Originally Posted by pyoungbl

The RX4 has a throttle body with a stepper motor to control idle speed by adjusting air bleed to the engine. There is no screw adjustment anywhere on the assembly. Some riders try to fool the ECU into thinking that the engine is running colder than the actual temp, just getting the ECU to inject more fuel. This 'fooler' is just an electrical resistor. Such a mod runs the real risk of over fueling across the board, washing the cylinders of oil needed for lube, and engine failure.

I just verified the lack of a screw by looking at the spare TB I have in my shop.

Bummer. It was just an outside of the box idea from another thread.

JFOlivier · 04-19-2022, 03:29 PM

I wonder if guys who put on other carbs with bigger jets also run the risk of too much fuel and washing their pistons dry, haven't heard of any problems though as I think that would take a lot of fuel and I am sure that the bike would not run too well. I one is to alter the air intake temperature by a small amount would it make any difference before the ECU cut it back from the low reading of the O2 sensor. Mt thinking to alter the fuel air mixture one would have to alter the O2 reading. The whole input output relationship of the ECU needs a little more explanation, is it open loop at the start going to closed loop when all parameters are reached.

pyoungbl · 04-19-2022, 07:30 PM

As I understand the system, you are running closed loop in the lower rpm conditions and open loop near full throttle. The O2 sensor will try to bring the mix back to a preset level but these O2 sensors are bargain basement parts with a very limited range of adjustment. That's common on motorcycles.

We have now exhausted my knowledge of how the ECU and its sensors work!

JFOlivier · 04-19-2022, 08:05 PM

the ECU is the future, It is only a control instrument. Where once control instruments were linear devices they are now programable digital devices. In the case of the ECU it has taken the place of the carburetor and also the CDI so we need to take an in depth look at the EFI side of the controller which has many inputs and a few outputs. which of the inputs actually effect the fuel injection rate and how does it effect this rate. If we can determine the range of these outputs we may be able to make small changes to these signals so that we could alter the algorithm. What effect are we looking at? maybe increasing the pulse width of the injector and could we possibly see this if an oscilloscope is connected to the fuel injector. The other way of course is to get into the program and make alterations but unfortunately that is beyond my expertise. Can ECU hacker help to see the results of any changes to the inputs are made. I am surprised that some software geeks have not already broken this stuff down to down loadable apps yet. Maybe we should ask our grand kids whether they can help.

wheelbender6 · 04-19-2022, 11:55 PM

According to JerryHawk, you can use an adjustable potentiometer in lieu of the resistor on the intake air temp wire. Easier to turn the knob on the potentiometer than replace resisters. Take regular plug readings to prevent running too rich or too lean.

pyoungbl · 04-20-2022, 10:24 AM

Adjusting the resistance leaves one with the same problem as before, the ECU will respond with more fuel across the entire rpm range. A good ECU map will try to maintain the mixture at a steady state but, in reality, many maps go from lean to rich and back to lean. This means that your 'fooler' might take care of a lean condition on parts of the map but a super rich condition elsewhere. The only way to know what's going on is to put the machine on the dyno. I have seen some very talented tuners who were able to build a map to flatten the mix but this is not something the average garage tuner can accomplish. If the Delphi ECU was used in large numbers of motorcycles we might see tuners stepping up to create a better map but that's not the case right now.

Personally, I do not have a problem with the fueling on my RX4. I'm keeping it stock, along with the intake and exhaust.

JFOlivier · 04-20-2022, 10:40 AM

Does anybody know what the EFI sensors do, the input air temperature does it increase or decrease fuel with a rising temperature. What about the input air pressure is this just an advance signal to the EFI as to how much fuel to add with an opening throttle position sensor? and then what does the cylinder temperature sensor do, my thought maybe the sensor that closes the loop when the engine reaches operating temperature which then leaves the O2 sensor in control of the fuel levels. Anyone care to help here.

pyoungbl · 04-20-2022, 12:13 PM

You might find this interesting...from Zongshen....

Sadly, does not really answer your questions about how the sensors interact with the ECU. My experience is with Ducati and Moto Guzzi ECUs. There the temp sensor adds fuel while the engine is cold...much like the choke with a carb. The air pressure sensor will adjust according to air pressure...that is altitude. Engine temp...probably another fuel adjustment. The thing is, each of these sensors act in concert with each other. It's not a simple additive process. You might see the air temp sensor telling the ECU to increase fuel while the air pressure sensor is saying to decrease, and so on. That's why making a new map is so difficult.

wheelbender6 · 04-21-2022, 10:43 AM

“Adjusting the resistance leaves one with the same problem as before, the ECU will respond with more fuel across the entire rpm range. A good ECU map will try to maintain the mixture at a steady state but, in reality, many maps go from lean to rich and back to lean. This means that your 'fooler' might take care of a lean condition on parts of the map but a super rich condition elsewhere.“

Hmmm. Sounds just like many of my carb jetting experiences.

08-01-2021, 01:34 PM	#1
Working_ZS Join Date: Aug 2016 Posts: 365	Tuning the RX4's Fuel Injection Over in the RX3 subforum, user Lukas has made considerable progress in accessing and modifying the Delphi ECU's fuel injection map. For those interested, the thread is here: http://www.chinariders.net/showthrea...d=1#post364185 Hopefully much, if not all of what he learns can be applied to the RX4's ECU for modifying its fuel injection mapping as well. There are definitely one or two areas where I would like for the RX4's fueling to be improved, with the light throttle, low speed stuff being at the top of my list.
	0

04-07-2022, 06:32 PM	#2
Bob Kelly Join Date: Jan 2022 Location: Weed, California. Posts: 271	Agreed I am also unhappy with the way my bike idles and the power just above idle ...as it is way way too lean !... as with any F.I. system they always tune for economy and emission control not performance..... and I would be very interested on how to change that... the bike needs it ! .... Bob....... __________________ It's too late when you've gone too far !
	0

04-07-2022, 06:46 PM	#3
Boatguy Join Date: Feb 2021 Location: Northeast Posts: 934	Just an idea outside the box. I remember there was a thread on here about my type of bike. Not the same thing at all. However, somebody was able to turn a screw on the air intake to adjust it so that the EFI tendency to run way too lean at idle was improved. __________________ 2020 Lifan x-pect
	0

04-19-2022, 11:55 PM	#11
wheelbender6 Join Date: May 2015 Location: Houston area Posts: 1,902	According to JerryHawk, you can use an adjustable potentiometer in lieu of the resistor on the intake air temp wire. Easier to turn the knob on the potentiometer than replace resisters. Take regular plug readings to prevent running too rich or too lean. __________________ "Its not WHAT you ride; its THAT you ride"
	0

04-21-2022, 10:43 AM	#15
wheelbender6 Join Date: May 2015 Location: Houston area Posts: 1,902	“Adjusting the resistance leaves one with the same problem as before, the ECU will respond with more fuel across the entire rpm range. A good ECU map will try to maintain the mixture at a steady state but, in reality, many maps go from lean to rich and back to lean. This means that your 'fooler' might take care of a lean condition on parts of the map but a super rich condition elsewhere.“ Hmmm. Sounds just like many of my carb jetting experiences. __________________ "Its not WHAT you ride; its THAT you ride"
	0

04-07-2022, 08:04 PM	#4
JFOlivier Join Date: Nov 2020 Location: Northern Neck of Virginia. Posts: 165	I read that posting from Lukas and found it interesting, I have a Lifan expect and would like to learn more about the ECU system so will try to get the hardware from Amazon. The first problem is that Lifan has their own ECU which is a Hunier EFI 9.0 whereas the other China bikes use the Delphi and the port plugs are not compatible. I have downloaded ECU Hacker and when I get the cables from Amazon I will have a stab at printing a plug to fit the Hunier plug but don't really know if the ECU Hacker will recognize tis ECU.
	1

04-19-2022, 10:42 AM	#6
pyoungbl Join Date: Feb 2016 Location: Portsmouth, Virginia, USA Posts: 632	The RX4 has a throttle body with a stepper motor to control idle speed by adjusting air bleed to the engine. There is no screw adjustment anywhere on the assembly. Some riders try to fool the ECU into thinking that the engine is running colder than the actual temp, just getting the ECU to inject more fuel. This 'fooler' is just an electrical resistor. Such a mod runs the real risk of over fueling across the board, washing the cylinders of oil needed for lube, and engine failure. I just verified the lack of a screw by looking at the spare TB I have in my shop.
	0

04-19-2022, 03:29 PM	#8
JFOlivier Join Date: Nov 2020 Location: Northern Neck of Virginia. Posts: 165	I wonder if guys who put on other carbs with bigger jets also run the risk of too much fuel and washing their pistons dry, haven't heard of any problems though as I think that would take a lot of fuel and I am sure that the bike would not run too well. I one is to alter the air intake temperature by a small amount would it make any difference before the ECU cut it back from the low reading of the O2 sensor. Mt thinking to alter the fuel air mixture one would have to alter the O2 reading. The whole input output relationship of the ECU needs a little more explanation, is it open loop at the start going to closed loop when all parameters are reached.
	0

04-19-2022, 07:30 PM	#9
pyoungbl Join Date: Feb 2016 Location: Portsmouth, Virginia, USA Posts: 632	As I understand the system, you are running closed loop in the lower rpm conditions and open loop near full throttle. The O2 sensor will try to bring the mix back to a preset level but these O2 sensors are bargain basement parts with a very limited range of adjustment. That's common on motorcycles. We have now exhausted my knowledge of how the ECU and its sensors work!
	0

04-19-2022, 08:05 PM	#10
JFOlivier Join Date: Nov 2020 Location: Northern Neck of Virginia. Posts: 165	the ECU is the future, It is only a control instrument. Where once control instruments were linear devices they are now programable digital devices. In the case of the ECU it has taken the place of the carburetor and also the CDI so we need to take an in depth look at the EFI side of the controller which has many inputs and a few outputs. which of the inputs actually effect the fuel injection rate and how does it effect this rate. If we can determine the range of these outputs we may be able to make small changes to these signals so that we could alter the algorithm. What effect are we looking at? maybe increasing the pulse width of the injector and could we possibly see this if an oscilloscope is connected to the fuel injector. The other way of course is to get into the program and make alterations but unfortunately that is beyond my expertise. Can ECU hacker help to see the results of any changes to the inputs are made. I am surprised that some software geeks have not already broken this stuff down to down loadable apps yet. Maybe we should ask our grand kids whether they can help.
	0

04-20-2022, 10:24 AM	#12
pyoungbl Join Date: Feb 2016 Location: Portsmouth, Virginia, USA Posts: 632	Adjusting the resistance leaves one with the same problem as before, the ECU will respond with more fuel across the entire rpm range. A good ECU map will try to maintain the mixture at a steady state but, in reality, many maps go from lean to rich and back to lean. This means that your 'fooler' might take care of a lean condition on parts of the map but a super rich condition elsewhere. The only way to know what's going on is to put the machine on the dyno. I have seen some very talented tuners who were able to build a map to flatten the mix but this is not something the average garage tuner can accomplish. If the Delphi ECU was used in large numbers of motorcycles we might see tuners stepping up to create a better map but that's not the case right now. Personally, I do not have a problem with the fueling on my RX4. I'm keeping it stock, along with the intake and exhaust.
	0

04-20-2022, 10:40 AM	#13
JFOlivier Join Date: Nov 2020 Location: Northern Neck of Virginia. Posts: 165	Does anybody know what the EFI sensors do, the input air temperature does it increase or decrease fuel with a rising temperature. What about the input air pressure is this just an advance signal to the EFI as to how much fuel to add with an opening throttle position sensor? and then what does the cylinder temperature sensor do, my thought maybe the sensor that closes the loop when the engine reaches operating temperature which then leaves the O2 sensor in control of the fuel levels. Anyone care to help here.
	0

04-20-2022, 12:13 PM	#14
pyoungbl Join Date: Feb 2016 Location: Portsmouth, Virginia, USA Posts: 632	You might find this interesting...from Zongshen.... Sadly, does not really answer your questions about how the sensors interact with the ECU. My experience is with Ducati and Moto Guzzi ECUs. There the temp sensor adds fuel while the engine is cold...much like the choke with a carb. The air pressure sensor will adjust according to air pressure...that is altitude. Engine temp...probably another fuel adjustment. The thing is, each of these sensors act in concert with each other. It's not a simple additive process. You might see the air temp sensor telling the ECU to increase fuel while the air pressure sensor is saying to decrease, and so on. That's why making a new map is so difficult.
	0