1985 Honda GL1200 Limited Edition Computerized Fuel Injection System Upgrade

Started thinking about this project when I bought the bike in 2015. wasn't until just before C-19 that I started to research it, and start getting my mind wrapped around a project of this magnitude, never thought it would morph into what it has.

Started with a replace the ECU because if the ECU goes "south", only options are a used ECU, the bike is parted out, the bike becomes a lawn ornament or boat anchor, or install an aftermarket ECU.

Looked at the installation of an aftermarket ECU, starting with the budget, most popular ones, MegaSquirt and Speeduino. Most others were not in the budget range. Settled on Speeduino because it is still in development, many new features being added, lots of variety depending on your requirement(s).

The Speeduino uses an interface board between the OEM system and the microprocessor, an Arduino Mega 2560. The only limitation with the Arduino microprocessor is the processing power and the program size limitation. For most of us the Arduino Mega will probably be more than needed.

The first Seepduino ECU was a Speeduino interface board v0.4.4 by Josh Stewart, with an Arduino Mega. Very capable, but did not have everything I wanted. Swapped out for a Spark Gap X4 by openlogicefi. Smaller footprint with integrated baro sensor, and other good attributes. The Ocelot by wmtonix is also another good alternative.

The Speeduino community is working on upgrading the Speeduino ECU microprocessor for more functionality.

The engine tuning software is Tuner Studio, and the data log analysis software is MegaLogViewer. Both excellent apps, but to get the most benefit out of these, you'll need to purchase a licence.

Have finally settled on a MaxxECU Sport for the final install. Changing out ECUs, even if they are budget ECUs, does get expensive. The MaxxECU Sport is a significant upgrade with the requisite cost. A fellow in Sweden that I correspond with is using the MaxxECU Mini, the baby of the family, which is a very capable ECU for any installation.

If a project like this is considered, I'd recommend a very realistic look at your requirements, because as I mention, changing ECUs can get expensive. The features/functions between the Speeduino and MaxxECU are very similar with some significant differences.

Next post will be on the requirements, I just wanted to start this thread and get started as @pegasus mentioned. It's a project that's not for the faint of heart.

Cheers

Most of this thread will be based on my personal experience and as such, I've made a lot of mistakes, but did make it to the road on several occasions with the Speeduino ECUs and now the MaxxECU.

A good piece of advice is to not try to duplicate the OEM CFI system design, we do not have the same tools available to us that Honda used.

Requirements - you should be naive, with a lack of understanding of the complexities of an EFI system, especially when there is very little information available regarding your EFI system.

It must be mentioned that a project of this magnitude, even an EFI conversion project, generally does not come to fruition. Time, patience, budget issues, all play a part in getting to the finish line. It's not a get it done quick for a first time DIY. My project is my retirement project and keeps me busy. You need a second bike available to keep your sanity.

I read, viewed, and repeated this for about 2 years while I accumulated the components I thought would be needed. This did not prepare me for what I was about to embark on.

The premise was to replace the Computerized Fuel Injection (CFI) system ECU and keep the OEM components that are already installed. Reverting back to the OEM configuration was a future possibility.

The system upgrade would reuse all CFI supporting components. The issue with this is that no component data is available for some of the more critical components such as the fuel injectors.

What can be reused?

Fuel injectors
Fuel system
Fuel injector resistor pack
Spark units (coil driver)
TPS
Coolant sensor (CLT)
Intake air temp sensor (IAT)
Crank and cam shaft trigger wheels
Coils
Pressure Balance (PB - MAP) Sensors with caveat
Crank shaft VR sensor
Cam shaft VR sensor (1) with caveat

The system would use the wasted spark and paired fuel injector strategies.

The lack of component data requires a user to determine the necessary component data through experimentation. The flip side to this is that the project will proceed faster than if you are tuning through experimentation, and the extra cost for components with component data is not a significant extra expense compared to bringing the project to fruition.

What components should be considered for an upgrade?

Fuel injectors - change up to high impedance fuel injectors from a reputable OEM such as Bosch. There is no data available for the OEM low impedance fuel injectors used, you'll need to pay a service shop to provide the data. The OEM fuel injectors or other older fuel injectors being considered should be serviced for flow rate and leak testing as a minimum. Upgrade to high impedance injectors gets rid of the resistor pack required for low impedance fuel injector use. This can be mitigated if the ECU of choice can utilize saturated and/or peak and hold fuel injectors.

Spark unit - change out for a modern coil driver that can handle up to 4 coils such as a Bosch 211 a four channel coil driver (no affiliation with Bosch). This coil driver is widely used in the EFI conversion world.

Consider going sequential fuel and ignition. In the long run, very advantageous. The '85 GFI system already has the crank and cam shaft inputs for this.

Change out the OEM coils for coil on plug units, One coil unit per cylinder. A coil with an integrated coil driver can be used, but it is rather large and space for installing non-OEM parts/components is at a premium.

The Fuel system should have the fuel pressure regulating (FPR) valve upgraded. This is because the OEM FPR maintains a fuel system pressure of 28 to 32 PSI, requiring you to derate any fuel injector being used. Most aftermarket FPR valves maintain a few system pressure around 3 Bar (43 PSI), fuel injector test pressure.

PB sensor(s) need to be replaced with the aftermarket ECU MAP sensor. Most aftermarket ECUs come with a MAP sensor installed on its interface board.

The cam shaft sensor(s) need to be replaced with a single Hall effect sensor. Depending on the aftermarket ECU, it may or may not be able to use a VR sensor because of the rotational speed, 1/2 that of the crankshaft.

The OEM CFI ECU has a barometric sensor, the new aftermarket ECU may or may not have one installed on the interface board.

You will need to install an O2 sensor in one of the exhaust headers, preferably a wide band O2 (WBO2) sensor.

The above information should get the creative juices flowing.

Cheers

Having posted the above information, and learning from the school of hard knocks, I need to detail the new configuration so that what follows will make some sense.

The new CFI configuration is:

MaxxECU Sport
Sequential fuel and ignition
Spark units have been replaced with a Bosch 211 four channel coil driver
Ford COP units
External Lowdoller Motorsport MAP sensor
Lowdoller Motorsport Fuel Pressure sensor
Hall effect sensors for crank and cam shaft sensors
OEM TPS
OEM Bosch 360 cc/min fuel injectors
MAP vacuum block - integrates all 4 cylinder vacuum connections
Aftermarket FPR valve - maintains system pressure at approximately 40 PSI
Dual O2 sensors, one for each cylinder bank

If I miss anything, I will mention it later.

First order of business, why settle on the MaxxECU Sport? My foray into the family of MaxxECUs started with a query from theailer in Sweden regarding my '85 ECU project. I had never heard of these ECUs, so did my homework and decided that this ECU would be more than I need, but it would check all the boxes.

The MaxxECU Sport attributes pertaining to my project:

The ECU can use multiple O2 sensors for the engine tune, not just use one and monitor another. This is a requirement for my project because it cannot be guaranteed that each cylinder bank will be the same, specifically since the bank being monitored can be tuned well, but the cylinder bank not being monitored can be operating in a lean or rich fuel condition.
It has a preset warning system that can be connected to the FUEL SYSTEM dash light to alert the user to a parameter issue
It has an Alert/Warning system that can be configured for various non-preset parameters
The MaxxECU has its own O2 sensors, or you can use aftermarket O2 sensors
Integrated CanBus
Proprietary MaxxECU engine tuning software MTune - provided with the ECU
Proprietary MaxxECU digital dash, MDash, that operates on an android cell phone or tablet, very configurable. Free for use.
Bluetooth capability to use the MDash app. The MDash app cannot be used with the lesser MaxxECUs, Mini and Street, would need to use a third party digital dash app such as RealDash connected to the ECU by cable

Note: Tuner Studio and MegaLogViewer are available in "light" versions, but to get the most from these, it's recommended that you pay for a licence.

It was recommended to me when I started the engine tune and setting it up, that I find an on-line course to focus my attention on the various aspects of engine tuning. Being a good DIY'er, I did not follow this advice, something like 'what man reads directions?' I have since, and because of this ECU, subscribed to an on-line course for the MaxxECU. I have found this to be valuable and it has taken a lot of the mystique out of learning the MaxxECU MTune software. Money well spent.

Overview of the MaxxECU Sport, and some of the attributes of the engine tuning software - An extremely well designed, forgiving (yes, we make mistakes), and high end aftermarket ECU with a plethora of good features/functions.

It comes with a substantial wiring harness, 10 feet in length. Every wire is labelled at intervals indicating what it is for. You must remove the OEM wiring harness connector and connect the MaxxECU wiring to it. You can remove the OEM harness wires that you will not be using such as wires for the fuel injectors.

A detailed wiring schematic is provided to assist with the install.

There is a good on-line information/documentation that is very detailed. It may require several readings, but it is a recommended read.

After purchase support from tech(s) that install these ECUs on a regular basis is available.

An understanding of the engine tune software terminology is required. There may be different terminology than other tuning software such as the terminology for a dual wheel ignition setup. Tuner Studio calls a crank and camshaft setup a "Dual Wheel" configuration. The MaxxECU calls this a "Multitooth + home" configuration.

The live tuning function applies to almost everything the ECU has a setting for. I have not found a setting/parameter that cannot be changed/adjusted "on the fly".

The engine tuning software can use multiple VE (fuel), ignition and O2 (Lambda) tables. It has additional VE and ignition tables for special requirements.

It monitors short and long term O2 readings and identifies the corrections required to bring these parameters into line with the target O@ readings.

Idle RPM can be controlled by the ECU such that over and under shoots are minimized or eliminated.

There are settings to increase the idle RPM when a high load appliance such as when a rad fan is operating, minimizing/eliminating engine droop.

There is a diagnostic section with some very nice features. You can shut the fuel, the ignition, or both off to a specific cylinder "on the fly" to determine if it is firing or not. When you do this, you monitor the O2 reading. There is an injector/coil wiring check that can be tested. The fuel pump can be cycled to make sure it's wired correctly and operates, same with the rad fan if the ECU controls its operation.

If you use an external MAP sensor, the on-board MAP sensor converts to a baro sensor.

The wiring for the coils and fuel injectors is cylinder specific regardless of the firing order. Once the coils and injectors are wired IAW the ECU requirements, there is an engine timing parameter that is set to the required firing order. For example. the coils and injectors are connected coil injector 1 to cylinder 1, coil/injector 2 to cylinder 2, and similar for cylinders 3 and 4. The firing order is 1-3-2-4, different from the 'Wing. The ECU uses the input firing order to operate the engine, not how the coils/injectors are wired.

The type of fuel that will be used is input. For gas you input 14.7, understood by the engine tune programming to be 14.7:1. It is recommended to monitor the O2 as Lambda, because Lambda never changes. If you change the fuel being used, you change the setting for the fuel to be used, and the ECU automatically changes the fuel injector pulse width to compensate. If you use AFR, whenever you change the fuel being used, you'll need to recalibrate the VE (fuel) table.

The MaxxECU Mini, the baby brother to the MaxxECU Sport, is more than capable of operating any 4 cylinder engine, including those with boost, VVT, and other such special requirements.

Most other features/functions are generally found on the budget aftermarket ECUs, but additional configuration may be required.

The MTune engine tuning software and MDash app can be downloaded off the MaxxECU web site. This will allow a potential user to peruse MTune and MDash to determine which MaxxECU is appropriate for the project, or if it is what is needed. My recommendation is to get the MaxxECU you need, not just want. This is true for any aftermarket ECU being considered. Regarding the MaxxECUs, if the MaxxECU Street meets the requirement, but there are features/functions that the MaxxECU Sport has that would be beneficial, purchase the Sport. Future proofing the ECU can be advantageous if you want to expand the project at a later date. Changing ECUs after the fact can get expensive.

A bit of an overview of the MaxxECU Sport - Most of the above, if not all, applies to the family of MaxxECUs.

Yes, bike is ride ready, on the road doing engine tuning.

Good morning @megagame. Project has evolved since I started. The new 360 cc/min high impedance fuel injectors are OEM Bosch, physical swap. Had issue with the Bosch clone fuel injectors regarding calibrating the VE table. The fuel injector latency affects the fuel injector pulse width. Too large a latency will result in a fuel rich pulse width, too small a latency will result in a lean fuel condition. The clone fuel injectors had a Bosch fuel injector P/N but that does not mean it is as per the OEM fuel injector. Found a business in Alberta that deals directly with Bosch and ordered new fuel injectors with fuel injector latency times, has made a significant difference.

Two O2 sensors is a budget ECU limitation. May not be an issue most of the time, but when dealing with two cylinder banks or a V-twin, it is definitely a benefit.

Have installed the external MAP sensor, the on-board MAP sensor is now used as a barometric sensor. A fuel pressure sensor is installed, it is used in the fuel injector pulse width calculation. This sensor feeds the ECU with real time fuel system pressure changes. These sensors are from Lowdoller Motorsports.

Looked at the "starter" function. There appears to be no benefit to using this feature, but time will tell. The '85/'86 1200 FI models had this feature, but what it is used for is unknown. I surmise it had to do with the cranking fuel enrichment on engine start.

Good morning. Fuel pressure doesn't fluctuate much. The fuel pressure regulator (FPR) I have installed is not the OEM FPR, it is one for a Subaru I think; however, it has a base fuel pressure of approximately 3 bar (43 PSI). The OEM FOR has a rating between 28 to 32 PSI. Either is good but trying to duplicate the OEM CFI system design is more of a heartache than needed. The excess fuel does get returned to the fuel tank, and the pressure differential across the fuel injector(s) should be the same at all times.

I do monitor the fuel pressure sensor output to the ECU and it is pretty constant.

Having a fuel pressure sensor for fuel pressure tracking is not really needed for a street, non turbo motorcycle. I incorporated it to have the experience of having done this mod. It's more of a conversation piece, the wow factor.

I installed an external MAP sensor, and because of this, the MaxxECU automatically switches the internal MAP sensor to a baro sensor. Have monitored this as well and there is a fuelling correction being done with elevation changes. If I wasn't able to have the baro reading on the digital dash, I would have to "assume" it was working.

I have lots of changes regarding the CFI system for my '85 FI model. It's a completely different CFI system and configuration.

It was mentioned on the Speeduino forum that most older, not always, EFI systems are a package deal and as such, the EFI system is designed for the average user and street use. Ignition timing is conservative, individual components are lumped together and made to work as a unit, and the OEM wants a system that protects the engine from us, and works well for everyday use. Upgrading the EFI system allows for better engine performance and daily operation, similar to the ECU upgrades for the Spyder world. Probably won't get any noticeable HP, or fuel economy increases, but you are able to "dial" in the engine tune instead of just accepting what you have. This is significant when there is an issue and the only way to fix would be to get into the ECU programming.

I have noticed that the engine "pulls" better in the 2000 to 3000 range, especially since I installed the OEM Bosch fuel injectors with the correct latency data.

A fellow I correspond with in Sweden, the one who got me hooked on the MaxxECU, is using an AI program/app to assist in fine tuning his 1200 engine tune. It's Claude Opus 4.8. He sent me a couple of his queries based on his data log. Lots of information to assimilate. He did mention that this does not replace the initial tuning of the VE and other tables, but can assist in the fine tuning. The human factor is not going away anytime soon. Shades of Star Trek.

Long winded answer, but there is and still is a lot for me to learn.

Cheers

When it comes to an EFI system or conversion, the KISS principle is the best, unless a person has some machiavellian tendency. I wanted to learn about the fuel pressure tracking, same with installing and using an external MAP sensor. All good. Other upgrades such as going sequential was for learning and I do agree that sequential, especially fuelling, is better than paired fuel injectors. Other nuances such as having the ECU control the rad fan is not as important, but a good learning experience.

A project such as my ECU upgrade that has morphed into a complete CFI system upgrade, is not for the faint of heart. It takes time and a dogged determination to complete and bring to fruition. Starting a project such as mine also brings into question "why can't I duplicate the OEM CFI system design?". No easy answers here.

AI, the new bane of our existence. Reminds me of the time back in the early '90s where I had to finally admit that DR DOS was not making it and I would have to accept the less capable MS DOS. I also realized at the same time that assembling PCs from scratch was quickly passing me by. The closest I get to those days is with my LINUX PC. Looking at the virtual PC for my LINUX PC because apparently the Mac platform is stopping support for PC based apps software.

Like you mention, back to the topic at hand. More to follow on the project.