1985 Limited Edition and 1986 SE-i Fuel Injection Motorcycles

[Rednaxs60]

Small update to this never ending saga. Wiring - the bane of our existence, specifically GROUNDS. having issue with getting the new ECU integrated and engine operating. No ECU sync. Without this, dead in the water. The fellow who designed the new ECU has been helpful, but still no cigar. Noticed the other day that when I was trying to get a sync signal, that the CFI system would restart, dash would go into the startup sequence. The only way for this to happen is an interruption in the power circuit, primarily the ground side.

Research into this indicates that ECU grounding is critical to the final operation. Already knew this, but expected there to be no issues considering this is an FI engine. Expect that these new ECUs are not as forgiving as the OEM ECU is.

There are several YouTube videos that discuss ECU grounding and what needs to be done. An issue is you never know what or how the OEM wiring harness is configured with regard to ECU grounding.

The issue is to separate the grounds, sensor grounds are grounded through the ECU, all others should go to a common battery ground. This is needed to keep "dirty" grounds, injectors-coils, fans, VVT solenoids and such, from impacting on the sensor grounds that need a "clean" ground.

A quick check with the ECU disconnected from the wiring harness is to check for continuity between the main ECU ground and sensor grounds. If there is continuity, there is an apparent wiring issue and you need to find it. This is where I am presently.

Where to now, check wiring continuity and find the issue.

Will report back.

 

[Rednaxs60]

The OEM wiring harness for the '85/'86 1200 GW FI models is a nightmare to understand and decipher, especially the ground wires. All grounds are tied together somewhere in the wiring harness. There are two grounding points at the front of the bike frame in line with the coils. The grounding points are a bolt welded onto the frame. The frame is used to connect the wiring harness grounds to the engine at the rear upper engine mount bolt. The battery negative cable is attached to this rear upper engine mount bolt. Simple in application.

Here's the rub. Research indicates that electrical system grounding should go directly to the engine, and not through the frame. The reason for this is that the electrical system grounding for specific electrical systems such as the EFI system, needs to be separate from high power or "dirty" grounds. I expect that Honda knows this and compensated for this in the OEM CFI ECU with filters and such.

This is not the case with an aftermarket ECU installation. These ECUs are generic and designed for a variety of installations. Wiring issues, especially ground circuits, must be well thought out, and will require some new wiring in place of the old.

I mentioned in my last post that high power, "dirty" grounds will affect the operation of the new aftermarket ECU. Engine starting can be affected in a no start scenario. Grounding for coils - must remember the spark plugs, fuel injectors, rad fans, electrical system additions such as heated clothing, extra lighting, and the EFI system are all on the same ground circuit. All grounding funnels back to the battery through the motorcycle frame. This scenario works and has worked well over the years with analogue systems, but digital systems that require a stable, "clean" power source are not as forgiving.

The engine is used because of the mass of the engine block. The engine block is a huge filter for the grounding system. For example, you could connect the ECU ground and the rad fan ground almost side by each, and the "dirty" rad fan ground would probably not affect the ECU "clean" ground requirement.

What happens when the new aftermarket ECU is connected into an existing OEM EFI system? There are many scenarios of incorrect ECU wiring that results in the engine not operating. One of these is voltage drop. As I research this issue, I am of the opinion that when the CFI system reboots, it is basically because of the voltage drop in the electrical system.

I understand, from a layman's perspective, what is being mentioned in the various web sites regarding this, and won't reiterate the information in this post because there is still a lot I do not understand; however, I get to reflect on what I have seen happen and understand the probable cause(s).

A "star" point grounding system is recommended for this scenario with the engine block being the "star" performer (pardon the pun). All grounds are routed to this point and connected with no intermediaries such as the motorcycle frame. You can choose a different grounding point, but the same applies, all grounds go to and through this one point.

Thinking about this "star"point grounding system for an existing OEM ground system such as the one on the 1200 GW, and the issues with the charging system and such, it is possible that over time, the original grounding system becomes problematic and issues come to the fore. The original grounding system cannot be ruled out when a charging system issue is being investigated.

As mentioned in my previous post, only have four ground points to consider, main battery ground, sensor ground, WBO2 sensor ground and one reference ground not used but tied to the main battery ground. Time to go hunting.

Cheers

 

[Rednaxs60]

Update on wiring - ground - issues. Noticed the other day that the dash reset while I was trying to get an engine sync. This has happened before but I could not put two and two together. I harkened this to a ground issue as I do with most wiring issues.

Research indicated that this was a ground issue, but more importantly a voltage drop issue. There are many reasons for a voltage drop in the electrical system, but most are caused by where the component or system is grounded. I am using a sequential coil-on-plug ignition system, and it has been mentioned on several websites and videos that a voltage drop to the ECU may not translate in a voltage drop to the COP units, and that COP units have been known to fire sporadically at voltages as low as 0.7V - not good.

I did a test of the ECU wiring and checked for continuity between the sensor ground and main ground, continuity. This is "bad" and you do not want this issue.

There is one reference ground not used and this is tied to the main ground. Cut these wires so that the OEM wiring harness is bypassed. Connected these two grounds directly to the battery. Checked for continuity between sensor and main ground, no continuity, good.

I have mentioned that the '85/'86 1200 GW FI models are power pigs, and research indicates that an EFI system is a power pig regardless of manufacturer. A drop in power supply to the ECU will have the ECU shut off until power supply is restored, hence the dash reset that I viewed.

I will be investigating how the ground wiring is done. I mentioned on my other thread that there are two grounding points on the 1200 GW one each side, in line with the coils. The frame is used to conduct the ground current back to the battery through the engine block battery connection, then to the battery.

A recommended ground wiring system is the "star" point ground. This can be the engine block - a good "dirty" ground sink, frame, or battery, but whichever you choose, you must use the same grounding point for all grounds. Mix and match of ground points is not a recommended scenario such as the frame and engine block in combination, use one or the other - not both, especially with a system that has digital components.

I'm thinking that a cable from the frame grounding points to the engine block, bypassing the engine frame (path of least resistance) may be beneficial. I'm wondering if the OEM ground system design is part of the charging issues that the 1200 GWs have been plagued with, great when new but not so much after a period of time.

More to follow.

 

[Rednaxs60]

Update: changed the ECU grounding, checked the engine timing, and started the engine. Got full sync at start, and all its well. Bit too much fuel right now, will be changing VERY soon table cell values soon.

Switched to paired fuel injectors to determine if I had a dash tach, no joy. Keeping sequential fuel and ignition.

Have wondered about the OEM wiring and how it might affect these new aftermarket ECUs, now I have a much better idea.

Time to finalize the wiring and continue with road trials.

For anyone thinking of an EFI conversion, check your ECU wiring. This issue is much like the idle on start and fuel smell to match, and using the TPS as the scapegoat. Can anyone say "going down the rabbit hole"?

Cheers

 

[Rednaxs60]

Flashback time. Old-New ECUs:


You might wonder, what I f you want to revert back to the OEM CFI ECU and CFI system, but why would you? Considering that with the new ECU you can now get at the engine tune and calibrate as required. There are challenges, but the benefits outweigh any downside.

Cheers

 

[Rednaxs60]

Update: Working on the ground wiring. Have changed the fuel pump ground, designated as a "dirty" (noisy) - high power ground. Thinking this is a good change. A short story about the grounding of components with pictures. First picture is a small portion of the OEM wiring harness. The green wires are grounds. You can imagine the interaction between all system components:

Mentioned I moved the fuel pump ground from the OEM wiring harness to the accessory fuse block ground from the battery. The fuel pump ground starts at the fuel pump, this is also the IAC valve ground at point 1. The fuel pump/IAC valve ground is connected to the OEM wiring harness at Point 2. The wiring harness ground is connected to the frame at point 3:

The grounds at point 3, left or right side, then travel through the frame to the engine ground (red arrow indicates) in this picture, then connected to the battery with an 8 gauge cable:

Quite the journey for the fuel pump/IAC valve ground. All electrical system grounds terminate this way. Moving the fuel pump/IAC valve ground almost directly to the battery should improve the health of the electrical system.

The rad fan will be my next consideration for ground relocation. I'm of the opinion that the rad fan ground is a "dirty" (noisy) high powered ground.

Cheers

 

[Rednaxs60]

This brings up an issue regarding ECU wiring and relays. There can be a few relays used to control EFI components and what the ECU controls. These can include fuel pump, wide band O2 controller, ignition coils, fuel injectors, fans (rad). Controlling the power to these components with relays ensures that when power is stopped, these components will stop as well. Power to fuel pump, WBO2 controller, ignition coils, and fuel injectors will be stopped when the ignition switch is turned to the OFF position, or the engine stop switch (kill switch) is opened.

The fans are another issue. Fans and the alternator have the ability to induce voltage into a system until these components come to a complete stop. This is an issue only when the engine stop switch (kill switch) fails and stays in the closed position when it should have opened. To ensure the EFI system ceases operation in the event of an accident, or the bike decides to lay on its side and take a nap so to speak, there is a tip sensor that cuts the power to the fuel pump relay and ignition coils - engine operation will cease.

Andy Whittle has a good video explaining this and I have borrowed his schematic regarding relays in an EFI system as attached. The number of relays and how these are configured to operate will depend on your installation:

Another aspect of an EFI installation that deserves consideration and planning.

I have looked at the OEM CFI system schematic regarding the tip sensor. It appears the tip sensor grounds the main CFI relay that provides power to the fuel pump relay, but once the tip sensor is activated, the ground is removed:


This schematic appears to tie into the original power supply to the coils before the coils. I expect that when the tip sensor is activated - bike on its side, the tip sensor provides a ground for the coil power supply and the coils no longer charge so there is no discharge through the spark plugs. Will have to ponder this for a bit to determine if my interpretation is correct.

Cheers