1985 GL1200 Limited ECU Replacement/Upgrade

This is where discussions of EFI systems, Dual Carbs, Single Carb mods and plans can be discussed and shared.

If you are working on or have a problem with stock carbs then your questions do not belong here, please post them in the Goldwing Tech Discussions Forum.

Moderators: sunnbobb, Neil, Forum Moderators

Post Reply
User avatar
Rednaxs60
Silver Member
Silver Member
Posts: 974
Joined: Mon Nov 30, 2015 11:14 pm
Location: Victoria, BC, Canada

1985 GL1200 Limited ECU Replacement/Upgrade

#1

Post by Rednaxs60 »

Have been reviewing the various forums/threads regarding EFI projects and have found these to be very informative. I have an '85 GL1200 Limited Edition with CFI, and it is my daily rider and project bike. Have been refurbishing it for the past 3 years. Have had to be innovative regarding parts, but that is to be expected. Just finished a winter work period, major item tackled was the heads. Compression had dropped below 100 PSI. Exhaust valves the culprit. Compression is now north of 160.

Still have a fuel/oil smell and some blue smoke on start. Investigated this. Pressurized the fuel system and did a borescope inspection of the backside of the intake valves. All four cylinders dry. Checked numbers 2 and 4 cylinders after sitting for a night on the side stand. Number 4 cylinder dry, number 2 cylinder some oil:
IMG_1693.JPG
IMG_1693.JPG (44.85 KiB) Viewed 3115 times
Not a big issue, but annoying. This will be the main item I will take care of this coming winter, rings and remove cylinder glaze. When I had the heads off, you could see the original cross hatch marking, but the cylinders were quite shiny. This work should finish off the mechanical work this bike needs.

Now to the subject of this thread. I have been learning about the CFI system since I bought the bike. I researched it before I bought it and some items came to the fore such as TPS and crank angle senor (Ns) replacement. Other areas that have been looked at and I have replaced are the PB sensors (MAP) with more modern Suzuki MAP sensors - better technology than the older Honda OEM Pb sensors.

The TPS is a linear rheostat so just about anything works. There is a catch with this in that the QA for these TPS components is sketchy at best. New TPS components can be problematic, found this out the hard way, right from the start. A faulty TPS can make the engine have "hard" misfires that feel like the engine is going to stop. Found a web site that had oscilloscope graphs showing good and faulty TPS components that were new. The faulty components had a lot of chatter in the mid range voltage that would send a faulty signal to the ECU and the ECU would react accordingly. Heat also affects these components adversely as well.

The Gr/Gl sensors - commonly called PG sensors - located on the back end of the right cylinder head, are not available but the folks over on the CX500-CX650 turbo forum have found the LX579 Sensors used in Dodge products are a suitable replacement component.

I have replaced the Ns sensor as well. My bike had the 1500 mod where the engine case had to be modded to allow the 1500 sensor to fit. I replaced this with a set of PG sensors from an '85 Aspencade that fit in the timing belt area. I have both installed but only use one. The second one will be a spare in case the one I am using fails. In having the second sensor installed won't have to get into the timing belt area, just have to switch the wiring under the shelter.

The primary components that make up the computerized fuel injection (CFI) system are:

Air temp sensor (T1)
Manifold pressure sensors (PBr/PBl) qty 2 - one for each cylinder bank
Throttle position sensor (TPS)
Coolant temp sensor (Tw)
Crankshaft angle sensor (Ns)
Cam shaft angle sensor (Gr/Gl)
Fuel pump relay
CFI main relay
Fuel shut-off sensor
ECU

I have been reviewing the literature about the Megasquirt unit and it is quite comprehensive, and there is a lot of it. I also read/reviewed the various forum threads regarding EFI projects.

Socrace, thesteve, irishcarbomb, toehead, FirstYearDeek, and taunusrainer (lots of other threads but can't mention everyone) threads have been very informative.

So far I have yet to find a thread on just an '85/'86 GW fuel injected bike ECU upgrade/replacement. My quest will be to, hopefully, achieve this without too much modification/component change out. I am intrigued; however, with socrace's use of Ford COP, and the various spark igniter units mentioned in the Megasquirt literature. The wasted spark coil in the Megasquirt literature is also interesting. Socrace also mentions that the spark igniter units used in the '85/'86 FI systems can be used.

I read on one of the threads where it was mentioned why one should go with EFI and the benefits of such. For myself, I prefer FI over carbs. When EFI came mainstream in the auto industry, my Father being a mechanic, thought he'd won the loto. Cold winter mornings, boosting and getting flooded cars going dropped to a minimum. Carb and EFI have issues. I believe socrace mentioned that dong an EFI project is like owning an older vintage bike, not for the faint of heart, and nothing is inexpensive.

The dual PB (MAP) sensors used by Honda has not been explained, and questioned in a few threads. I have read where a fellow did "marry" the two into one, use a splitter to connect back into the system and everything worked fine. I think this is completely plausible. To upgrade to the Megasquirt unit, this is probably what will have to happen - not a big issue.

Socrace has mentioned that the Honda OEM TPS can be used, but any linear TPS can be also. Have used a TPS for an early model Civic as a replacement for the Honda OEM unit, worked fine once I got a good one.

The '85 LTD has an 8 tooth trigger wheel for the crankshaft sensor (Ns). Read about using a 36-1 but would have to research this. The GL1500 has a 12-1 trigger wheel that would probably fit in place of the '85 LTD Ns 8 tooth trigger wheel. Possible alternative.

The Gr/Gl (PG) sensors on the backend of the right cylinder head was mentioned in the Megasquirt manual. Single tooth that will apparently work, but a change to a 12 tooth trigger in place of is recommended.

There is discussion regarding the OEM injectors for the '85 LTD. I had mine cleaned and the flow results came in at 65 ml/min after cleaning. The numbers before cleaning were 64 ml/min. Pressure setting for injector test(s) was 40 PSI. The injector resistance reading was 2.6 ohms for each. The original Honda OEM injectors are quite robust. These injectors are being used in several projects and I have been taking notes regarding the injector impact on tuning the EFI system.

The fuel pump requirement is for 630 cc/min minimum. Static pressure is 34-38 PSI and dynamic 28-34. My system came in at 38 PSI static, and 36 PSI dynamic. When I was searching for the reason I had a fuel/oil smell on start, I pressurized the fuel system and let it sit. Pressure dropped 12 PSI in one hour. Think this is a bit excessive so I am looking for a suitable fuel pressure regulating valve that will fit where the original is.

The idle air control system is a passive system that works quite well for its design. The idle air control (IAC) valve is activated by a bi-metallic element (courtesy of socrace). The IAC valve is wired in parallel with the fuel pump - fuel pump on power to IAC valve. It is never fully closed even when cold and not used for a while. The water system hoses connected to the IAC valve are to prevent freeze up in colder climates, other than this requirement, no need to have a water heated valve. The reed valves work quite well and are operated by cylinder vacuum. I replaced the IAC system hoses, but when I installed the air chamber one of the hoses came off the right side reed valve (had to remove air chamber to repair). These reed valves suck a lot of air and the noise is quite loud. If you did not know better, you would think there was a metal on metal issue, I did, But when I investigated using a stethoscope (Long screwdriver) there was no internal metal noises. The Megasquirt literature I have read indicates that this passive IAC system is acceptable.

Here are twp pics of the IAC valve internals. This is when cold:
IAC VV air opening when cold.jpg
IAC VV air opening when cold.jpg (38.91 KiB) Viewed 3115 times
This when bi=metallic strip heated opening IAC valve:
IAC VV air opening when warm.jpg
IAC VV air opening when warm.jpg (20.88 KiB) Viewed 3115 times
There will always be IAC system air going into the engine. The IAC system is not just for operation when cold, but provides air when the throttle is shut, cutting off air to the cylinder(s). A small amount of air bypasses the throttle plate(s). Here is a picture of the IAC system:
Air Chamber Underside 2.jpg
Air Chamber Underside 2.jpg (47.1 KiB) Viewed 3115 times
You can see the reed valves and where the output from the reed valve(s) is on the cylinder side of the throttle plate(s).

I mentioned that a hose came off the right side reed valve when I out the air chamber back in. The hose size is approximately 1/2 inch or so. This is a picture of what I found:
IAC System.jpg
IAC System.jpg (110.06 KiB) Viewed 3115 times
The lower arrow is where the IAC valve gets its air supply.

I think I've come to the end of my introduction into the Megasquirt world, and the quest for a suitable ECU upgrade/replacement. More to follow.

Cheers
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
User avatar
Rednaxs60
Silver Member
Silver Member
Posts: 974
Joined: Mon Nov 30, 2015 11:14 pm
Location: Victoria, BC, Canada

Re: 1985 GL1200 Limited ECU Replacement/Upgrade

#2

Post by Rednaxs60 »

Had some home chores to do, but this gives me time to reflect on all the information I have been reading.

My thoughts have been turning towards the ignition requirements. The '85 LTD ECU uses the crank angle sensor (Ns), PB sensors (MAP), TPS (0th), Gr/Gl sensors (PG), and coolant temp (Tw) for ignition timing. The PB sensors are good up to approximately 3000 RPM, after which these components are not used in the equation. I mention this because in testing these components on the bench, these max out for voltage at approximately 13 in Hg.

Coolant temp is monitored, and while used for ignition timing, I surmise that it is also part of the fast idle aspect of the '85 LTD. The same can be said for the air temp (T1) sensor - used for fast idle, but once the engine warms up, and you can watch the correlation between the engine temp and the idle speed - engine warms up, RPM drops.

The T1 sensor detects air temp and sends signals to the ECU. The service manual supplement for the '85 LTD does not go further into a description for this sensor. Has to impact on the timing especially on start.

I have compared the schematics, the '85 LTD against the Megasquirt-2 V3.0/V3.57 wiring and these are quite similar. It will take me a few reviews to digest the similarities and how these can be adapted. As I mentioned in my previous post, I want this to be an upgrade/replacement with not too many alterations if possible.

The GW ECU and the Megasquirt appear to operate the same in that each unit controls the ground of the component to be controlled such as the coils, injectors.

The Megasquirt schematic has a main and fuel pump relay similar to the '85 LTD. The wiring is much the same because of this.

I have mentioned that the PB sensors can probably be consolidated into one. To prove this I think I will make a splitter so that I can operate the bike off one PB sensor. This would prove a theory I have, and this understanding would be beneficial when upgrading the OEM ECU.

I have to confirm that a passive IAC system can still be used with an upgrade/replacement ECU - more reading to do.

The inputs to the ECU that allows the ECU to control the engine operation are next on my list of things to think about.

Printed out the Megasquirt MS3 Gold Box V1.2 Hardware manual this afternoon. It appears to be similar to the Megasquirt MS2V3.0 Hardware Guide. More information to digest.

Cheers
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
User avatar
Rednaxs60
Silver Member
Silver Member
Posts: 974
Joined: Mon Nov 30, 2015 11:14 pm
Location: Victoria, BC, Canada

Re: 1985 GL1200 Limited ECU Replacement/Upgrade

#3

Post by Rednaxs60 »

In contact with DIYautotune regarding the application - very helpful folks. Matt at DIYautotune mentioned that if I want to stay with bank to bank fueling I can use the Microsquirt, or upgrade to the MS3 to do more such as sequential fuel control. Matt also mentions that the cam angle sensors - Gr/Gl sensors (PG) on the rear of the of the right cylinder head can be reduced to one sensor/signal for use with the Megasquirt. This would be beneficial in that there would be a spare cam shaft angle sensor available should one fail. He also mentioned that the 8 tooth trigger wheel for the crank angle sensor (Ns) will work as well. I think I should stay as close as possible to original build, but have the ability to tune the system for new components should the old ones have to be changed out. Thinking the Megasquirt MS2 with the latest boards/software would be best.

I have been looking on the internet to determine what a used ECU would cost and have found one and it is close to $300.00 CDN. A new MS2is approximately $500.00 CDN and can be tuned, great possibilities and with new technology.

I have been reading on line where there is an ITB (independent throttle body ?) map that uses an Alpha-n and speed density values. Speed density initially uses the MAP, this would be the PB sensors of the '85 LTD FI system. It has been questioned why there are two PB sensors on the '85 LTD FI system, but that is what Honda did. I have read where this could be changed so that only one PB sensor is used, but for the OEM installation you would still have to split the signal and connect to the CFI system as if you were using two PB sensors.

The speed density mode uses MAP, TPS, temperature and RPM to control the engine. This can be converted so that all that is being used is RPM, temperature and TPS, making it the Alpha-N mode. The Alpha-N mode uses TPS and RPM to calculate the fuel amount to be injected instead of MAP and RPM in the speed density mode. This is how the '85 LTD FI system operates. The CFI system uses the PB (MAP) signal up to around 3000 RPM, after which it discounts this signal - believe it is maxed out - and uses TPS and RPM as the main signals for engine operation.

The MS unit needs a TPS signal of "0" with throttle closed. Going to check the TPS calibration to determine how close the TPS is to "0" after calibration.

Have learned a little more, but still a lot of homework to do. Cheers
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
User avatar
JBz
SUPER BIKER!!!!
SUPER BIKER!!!!
Posts: 3070
Joined: Wed Jan 31, 2007 8:11 pm
Location: dayton nv

Re: 1985 GL1200 Limited ECU Replacement/Upgrade

#4

Post by JBz »

good article. I tried the megasquirt but still havent got it running. Got brain DEAD on it a few years ago and havent got back to it. my Articles on this forum under jbz.Need someone smarter than me.LOL. I got a supposedly nos factory ecu in the cabinet I dont think ill ever use. The big guy that sits under the trunk. I machined a 36-1 wheel the same diameter as the stock one. I think that might be the problem as I only got one spark on start and no more Too small to pick up the gap with the stock under belt factory pickup. Good Luck......JB
jbz........... Thinkin about sh-t too hard and You wont get anything done
User avatar
Rednaxs60
Silver Member
Silver Member
Posts: 974
Joined: Mon Nov 30, 2015 11:14 pm
Location: Victoria, BC, Canada

Re: 1985 GL1200 Limited ECU Replacement/Upgrade

#5

Post by Rednaxs60 »

JBz wrote:good article. I tried the megasquirt but still havent got it running. Got brain DEAD on it a few years ago and havent got back to it. my Articles on this forum under jbz.Need someone smarter than me.LOL. I got a supposedly nos factory ecu in the cabinet I dont think ill ever use. The big guy that sits under the trunk. I machined a 36-1 wheel the same diameter as the stock one. I think that might be the problem as I only got one spark on start and no more Too small to pick up the gap with the stock under belt factory pickup. Good Luck......JB
JB - thanks. Have scoured the forums and still picking up information when I read the threads again. Yours has been looked at as well. I understand your "brain dead" issue. Picked up my '85 LTD 3 years ago and have been refurbishing it ever since. I too, get to a point every now and then wondering what I got myself into. Tackling issues with the engine and some blow by. Did the heads this past winter, found the issue regarding fuel/oil smell and some blue smoke on cold start, and will be doing the rings this coming fall/winter. Once this is done, CFI project. My thoughts are that having an engine that is tight and operating well will go a long way in getting a new ECU installed.

The OEM ECU is quite robust, and has stood the test of time, but nothing lasts forever. I would consider one like your dust collector, but not many out there for sale, and the price is generally cost prohibitive - the exchange sucks. We don't have as large a GW base up here north of the border. The system as a whole is as bulletproof as you can get for the time.

The '82 CX500 and '83 CX650 turbos have similar CFI systems as well. Lots of good info on the CX500/650 forum as well.

I have found a CDN source for the MS in Ontario, and from my research to date the MEGASQUIRT II 3.57 ASSEMBLED ECU appears to be the front runner. Will compare to DIYautotune for cost mainly because of support - technical support in this endeavour is quite important.

Came to another issue last night. Lots of info to digest. I have the travel computer on my bike, great piece of kit, still haven't figured out or used all the functions. It's a legal driving while distracted device as it is incorporated as part of the bike. I'm certain it uses a lot of the signals from the sensors to provide the info it does. Went onto the DIYautotune website and found its article on wiring the MS in parallel with the OEM ECU so that I can keep the travel computer functionality, but use the MS for engine operation. The article does mention that there are signals that the MS does not like to share so will be looking into what is needed.

Have read socrace's thread on coil on plugs (COP) and how he achieved the upgrade. Also found a YouTube video where a car was upgraded to COP, car had a wasted spark system as well. The car video just split the signal to the original coil into two and connected the new COP units. Socrace's is a bit more involved, but there is always more than one way to achieve the aim. I like the COP concept and application. It has benefits that the OEM wasted spark setup does not, and it is less expensive. Would like to see how socrace married the COP to the OEM plug boot. This upgrade would be beneficial even if no ECU upgrade/replacement is done.

It was commented on in an EFI thread that the original CFI system, while functional, lacked the nuances of the newer technologies, yes I agree, but when Honda did this back in the '80s, state of the art and on the cutting edge. We now get to reap the benefits of the past 30 odd years, and can keep these older FI bikes on the road, and see what can be done with the ability to do tuning.

Lots to do. Cheers
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
User avatar
Rednaxs60
Silver Member
Silver Member
Posts: 974
Joined: Mon Nov 30, 2015 11:14 pm
Location: Victoria, BC, Canada

Re: 1985 GL1200 Limited ECU Replacement/Upgrade

#6

Post by Rednaxs60 »

Starting to read into the Megasquirt unit. Lots of information to digest, but quite informative. Been through the "Injectors and Fuel System" literature. Have a handle on this one, but will be reading again.

Question regarding the Megasquirt unit. Ready made or DIY? Did soldering on circuit boards many moons ago, but would be extremely rusty at this point. Worth the headache, time and resources as a DIY project, or just bite the bullet and get a ready made? Tending towards the ready made simply because I will be doing an upgrade/replacement of the ECU not a complete build.

Starting in on the "Tuning Your Megasquirt". This section mentions that having an operating system is extremely beneficial. Mine is working well so this is a system upgrade/replacement project. I will also have the benefit of having the system tuned so that the input to and outputs from the Megasquirt should be easier. This section also indicates that you do not need an O2 sensor for the system to operate, page 6.

Have looked at the MAP requirement. The '85 LTD has two PB (MAP) sensors. I have commented on these before. I looked at the service manual supplement and there is a troubleshooting guide for these sensors with the required specs for the PB sensors. Have to correlate these values to what is needed by the Megasquirt unit for programming.

Did a comparison between the OEM PB sensors and the Suzuki MAP sensors. Info regarding is:

Brand: Denso.
Type number: 100798-5630. Suzuki ordering number: 15620-35F00.
Suzuki description: Sensor Boost, IAP (Inlet Air Pressure) sensor.

The reason for this is the fellows on the CX500-CX650 turbo forum needed replacement units for their turbo bikes and the Suzuki sensors were found to be acceptable alternatives. One of the fellows took an OEM PB sensor apart and found the manufacturing technique for joining the wires in the OEM PB sensor was less than adequate by today's standard(s). I have been using these in place of the OEM PB sensors for the past two years and all is well. Here is the CX500-CX650 turbo thread: https://cx500forum.com/forum/cx500-cx65 ... ement.html

I did a bench test comparison between the two sensors as follows:

The power source for this was 3 - AA batteries in series giving me 4.8 VDC. I hooked up a test circuit with multimeter. Here are my readings, read in 3 columns - inches of Hg/Suzuki sensor - VDC/Honda OEM PB sensor - VDC:

0 in Hg/3.45/3.63
5 in Hg/3.1/3.14
10 in Hg/2.65/2.59
15 in Hg/2.18/2.0
20 in Hg/1.73/1.43
25 in Hg/1.26/0.88

The table below is from the supplement:

Service manual supplement Test Vacuum specs for the PB (MAP) sensors, read in 5 columns; mm HG/in HG; kPa; kg/cm2; psi; output voltage:

100-3.94/13.73/0.14/1.93/2.85-3.50V
300-11.81/40.21/0.41/5.83/2.16-2.45V
500-19.68/66.69/0.68/9.67/1.21-1.40V

Have some readings to do regarding the kPa requirement for the Megasquirt.

Need to further look at the TPS signal and correlate it to what is needed for the Megasquirt. Need to correlate the calibration procedure in the supplement to the Megasquirt requirements.

More to follow. Cheers
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
User avatar
Rednaxs60
Silver Member
Silver Member
Posts: 974
Joined: Mon Nov 30, 2015 11:14 pm
Location: Victoria, BC, Canada

Re: 1985 GL1200 Limited ECU Replacement/Upgrade

#7

Post by Rednaxs60 »

Have been reading the literature for the Megasquirt units, browsing the web for info on trigger wheels and exactly how these work and correlate the cam/crank signals. Reading the threads on the various EFI projects again, and gleaning/learning more each time.

The bones of the EFI system are there with the exception of the O2 sensor, and this can be worked around if needed. The injectors are fine and can be used with the OEM resistor pack, or the pulse width modulation (PWM) that Megasquirt is programmed with. Using high impedance injectors would probably be a good change. The TPS sensor can be reused, as can the spark igniters; however, the spark igniters can be changed for the 7/8 pin GM HEI igniters that apparently work well with the Megasquirt. COP units would also be beneficial, but there is a space limitation that I have to assess. The CFI covers don't allow for a lot of flexibility for injector orientation. Using COP units would eventually have me look at sequential injector/ignition.

The COP and the GM HEI spark igniter units may be a good interim project that enhances the EFI system as installed. Will be thinking on this one.

The IAC circuit is presently a passive system, but most of the literature is for an active system for fast idle control. Going to an active system appears to work well with Megasquirt, and if so, the unit would probably fit where the OEM IAC valve placement is.

Matt at DIYAutoTune has mentioned that the 8 tooth crank trigger wheel can be used, as can one of the sensors on the cam. Would only have to disconnect one of the cam sensors, Gr or Gl from the system. This would give me an 8/1 trigger wheel system.

The MAP sensor can be a single unit as installed, and the water/air sensors can be reused.

With real estate being at a premium under the shelter and such, would use the existing fuse panel relays.

The Megasquirt units support an ITB mode that uses the MAP sensor up to approximately 3000 RPM and then goes to a TPS-RPM mix much like what is presently being used by the OEM. This is good news as the system works well in this configuration/mode.

With all this want to keep the dash working and the travel computer.

The other interesting aspect of the Megasquirt unit(s) is the CAN Comms. Will be looking into this, but it is a secondary consideration.

The wiring would have to be looked at, but it should be a beneficial exercise. Think that Honda used a lot of wire that might not have been needed. A rework of what I have done could probably result in fewer wire runs as well. If a new wiring loom for the Megasquirt is used, I would make it so that it would be compatible with the OEM system just in case a reversal is needed. Need to find a good electrical wiring program that is easy for us older gents to use.

One issue is with the original grounding system. Lots of wires going forward mainly because the main ground points are all located at the front. Using selective ground buses would eliminate a lot of wire.

Trying to keep all this information straight is a challenge. Feel the better the prep work, the better the implementation later on.

Cheers
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
User avatar
Rednaxs60
Silver Member
Silver Member
Posts: 974
Joined: Mon Nov 30, 2015 11:14 pm
Location: Victoria, BC, Canada

Re: 1985 GL1200 Limited ECU Replacement/Upgrade

#8

Post by Rednaxs60 »

More research done. Find the Megasquirt literature extremely detailed, and at this stage not necessary. The Megasquirt ECU manuals are good, as are the threads I've been reading and reading again.

I have been watching some YouTube videos regarding the Megasquirt setup, using the ITB mode and others. The fellow who is doing these, Andy Whittle, narrates and explains the video concept at my level of understanding.

Looked at some of the PDF files I have and have found the pin placement for the '85/'86 LTD/SE-i:
Travel Computer-ECU Pin Schematic.pdf
(281.18 KiB) Downloaded 108 times
Since I am looking for an upgrade replacement ECU, this will be extremely beneficial. The schematics detail the connections and if newer components are integrated, should be able to use the existing wiring. Using the OEM wiring harness to connect a new/newer ECU unit should keep all other OEM components working.

I have been looking for a ready made Megasquirt unit, and fairly certain that I will be settling on the MS3 unit. It comes with an integral MAP sensor that would replace the dual OEM CFI setup. This unit is very flexible with regards to injector/coil firing. A lesser unit would be more work because the OEM CFI system does not leave you with an option of controlling just the fuel, you must do fuel and timing as a minimum.

Info on the 8 tooth crank trigger wheel, and the cam trigger wheel. From Clymers: This 8 tooth trigger wheel sends out 8 pulses per revolution. The ECU then triggers the fuel injector at the 4th pulse after a TDC pulse is received from the camshaft angle sensors. This information is used to control the ignition timing and fuel injection volume accurately. Good explanation of the correlation between the crank and cam sensors, and is a feel good indication that the 8/1 trigger wheel setup will work with the Megasquirt unit. The Megasquirt unit apparently only requires one cam shaft trigger, not the dual OEM setup.

The OEM fuel pressure requirements is for a static pressure (not operating) of 34 to 38 PSI. Operating pressure of 28 to 34 PSI. Had the injectors cleaned and flow tested at 40 PSI. Injectors flow rate was 65 ml each after cleaning. Most literature that I have read indicates that a constant fuel pressure of 40 PSI should be used, but the OEM system does not require this.

The '85/'86 FI bikes have a fast idle circuit, but the IAC system does not control it. The IAC system is a passive system that relies on manifold vacuum to activate the reed valves to draw additional air into the intake during cold start and at other times such as when the throttle plates are closed on deceleration. I have not found any information on how the OEM CFI fast idle works, but surmise that the ECU uses air/coolant temp to advance the timing at start, and uses coolant temperature to control this timing advance. I mention this because my '85 has a fast idle and as the engine gets warmer the idle will start to decrease until the engine is at operating temp and the idle is at the recommended setting. It is recommended to use a stepper motor with the Megasquirt that holds the throttle slightly open on cold start and closes as the engine comes up to operating temp.

Just a short update, but keeps me focused.

Cheers
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
socrace
Titanium Member
Titanium Member
Posts: 334
Joined: Sun Aug 16, 2009 11:46 pm
Location: Springfield, Ill.

Re: 1985 GL1200 Limited ECU Replacement/Upgrade

#9

Post by socrace »

Good write-up Ernest!
Using a Megasquirt 3 ECU to replace the oem Honda unit seems doable, although a little pricey at around US$700+.
But, that's not much more than some of the ignition options out there that cost $500+ (with no fuel injection), so maybe not so out of line.
The microsquirt I'm using is still being sold I think for around $400. Am using non-honda crank and cam sensors, but can probably be adapted to the oem ones.
Bob D
1981 Goldwing Standard - efi'd, other stuff
User avatar
Rednaxs60
Silver Member
Silver Member
Posts: 974
Joined: Mon Nov 30, 2015 11:14 pm
Location: Victoria, BC, Canada

Re: 1985 GL1200 Limited ECU Replacement/Upgrade

#10

Post by Rednaxs60 »

Bob - was wondering when/if you were going to chime in. Trust all is well and you're having a great Easter.

Are you still riding your 1100 with the FI mod? Have read your thread(s) as well as others quite a few times. Glean a little more each time as I become more familiar with the CFI system on my '85 LTD.

The MS3 unit here in the north is $1K because of exchange and such. I have to do fuel and ignition timing as well as use the existing sensors, could probably muddle through add-ons, but prefer not to go in that direction - don't have the equipment nor the expertise at this time. Would rather have the extras available and not use, then to not have and need. Do appreciate the posts on the different components and some of them may be considered.

Matt at DIYAutoTune mentioned that the 8 tooth crank trigger wheel can be used as well as one of the cam sensors. Have thought about what Honda did and it makes sense in a weird way. The FI system on the '85/'86 LTD/SE-i bikes was a variant of the CFI system on the CX500/CX650 turbos and what Honda achieved in the mid '80s with EFI was quite the accomplishment.

Have ordered the EFI book, Performance Fuel Injection Systems, that DIYAutoTune sells (bought it on Amazon.ca) for more information.

I'm not expecting any significant difference in engine performance with this upgrade/replacement, but I am expecting the overall operation to be much better. As has been mentioned on several threads, the OEM CFI system is older technology and has done a good job, but advances and improvements over the years can enhance the engine operation. It has also been mentioned that the Honda flat four engines with the newer electronic components are an extremely powerful engine. Honda did something right.

I'm very excited about this project especially since it is not a redesign or build, but a replacement that needs to be adapted to the OEM system. I can wire and tune the unit, but if I had to do a build, it would not be considered. I remember reading a web site that discussed this very point. If you want EFI, the easiest and least expensive way to achieve it is to buy the vehicle you want with it installed. This is not to say that replacing components is not inexpensive, but that it is easier to keep a system going when you are only concerned with components.

I'm still a novice at this, but like a good challenge.

Cheers
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
socrace
Titanium Member
Titanium Member
Posts: 334
Joined: Sun Aug 16, 2009 11:46 pm
Location: Springfield, Ill.

Re: 1985 GL1200 Limited ECU Replacement/Upgrade

#11

Post by socrace »

Looking forward to following along on your project!
Just started up my efi'd '81 GL for the first time this year. Always amazed at the basic refinement of these old Hondas; like riding on a cloud compared to most bikes I've ridden over the years.
The book title you mentioned was actually written by Matt at DIYAutoTune, so I would trust his advice.
Bob D
1981 Goldwing Standard - efi'd, other stuff
User avatar
Rednaxs60
Silver Member
Silver Member
Posts: 974
Joined: Mon Nov 30, 2015 11:14 pm
Location: Victoria, BC, Canada

Re: 1985 GL1200 Limited ECU Replacement/Upgrade

#12

Post by Rednaxs60 »

Quick update. Received the book "Performance Fuel Injection Systems" by Matt Cramer and Jerry Hoffman. Have read through it as well as my other book "Motorcycle Fuel Injection Handbook" by Adam Wade. Between the two a lot of questions have been answered, but have some additional questions as well. In addition to these books, have been perusing the Megasquirt manuals and Megasquirt documentation.

I have put together spreadsheets for OEM ECU pin designations, and correlating these to the travel computer, and LCD dash. Doing this so that I can determine how the replacement may affect the overall system. Have to look into the "User Defined" pins of the Megasquirt to understand how these work.

The TPS, crank (Ns), and cam (Gr/Gl) sensors as fitted can all be used. Megasquirt documentation indicates that the two cam sensor arrangement is not supported by the Megasquirt unit - this is corroborated by Matt Cramer at DIYAutoTune as well (email correspondence), but that one can be used.

The crank sensor uses an 8 tooth wheel that can also be used, Matt Cramer has indicated that a 12 tooth would be better, but finding a 12 tooth wheel that would fit/work may be a quest onto itself.

The crank sensor is interesting as well. There are two mounting positions exactly 180 degrees apart. Either position can be used on the '85 1200 FI system with no change to any other parameter. I can vouch for this because the OEM sensor failed sometime before I bought the bike. It is the subject of a thread on Steve Saunders forum where the fix was to install a 1500 sensor in its place. The PO installed the 1500 sensor in the upper position by modifying the mounting screw bosses (removed some of the aluminum boss) so that the 1500 sensor was installed to coincide with the 8 tooth trigger wheel. I have since removed the 1500 sensor, and mounted a set of PG sensors from an '85 Aspencade. This PG sensor install has a sensor mounted in the upper and lower position (Honda used the same block for both models), but have only one of the sensors hooked into the CFI system. The second sensor is there in case the one being used fails, then its just a wiring change under the shelter, and I don't have to go into the timing belt area.

I will be doing an investigating into the engine timing to determine the position of #1 TDC and how it relates to the crank/cam position sensors. Should be able to determine the various other piston TDC positions as well.

The engine firing is 1-3-2-4. As is known the waste spark is for cylinders 1-2, and 3-4. The injectors are a bank to bank firing pattern for 1-3 and 2-4. My thoughts on this are to continue initially with the wasted spark system, but change the injectors to sequential firing. This will assist in reducing what goes out the back end.

I have been contemplating the OEM spark igniters, specifically how these work. The OEM spark igniters for the '85 LTD FI system are 4 wire units. There are three 12 volt wires and a ground. I have come to the realization that these spark igniters are a very specialized relay, much like a basic automotive relay. My understanding is that the ECU grounds the 12 VDC supplied battery voltage to ground and in doing so the spark igniter internal "coil" switch is closed, allowing power to flow through the primary winding of the coil(s). At some programmed time, the ground for the 12 VDC supplied battery voltage to the spark igniter is stopped/removed, and the internal "coil" switch is opened, sending the amassed power out through the secondary coil to the plugs.

The CFI system does not have an O2 sensor, and I have not fully looked into whether this is a show stopper at this point, but reading the Megasquirt literature indicates that this is not. The primary benefit from an O2 sensor, as I understand it, is for tuning at idle so will investigate this for install.

The '85 LTD FI system uses an ITB mode for operation. The initial mode is speed density because a MAP sensors (PBR/PBL) are used up to about 3000 RPM after which the mode reverts to an n-alpha mode (n for engine speed, and alpha for throttle angle). If this is not quite correct, then Honda has one intricate ECU in that it uses all the inputs and chooses the appropriate part of the 3D control maps to operate the engine based on an n-alpha mode. Be an interesting hack to look at the 3D control maps for the '85 LTD and '86 SE-i for someone in retirement.

A Readers Digest version of this can be found at: https://powersports.honda.com/Experienc ... c0812182ba

The OEM ECU has an integrated self diagnostic system that, if there is a fault in the electrical portion of the CFI system, the "Fuel System" dash fault light will come on and an error code or codes will be displayed on the ECU. I surmise this is the forerunner of the OBD scanners that are in use today. I have not determined how this will be integrated into a new ECU such as the Megasquirt.

I think I have my thoughts on this issue focused in the right direction. Still a lot to research to compile, and will be perusing the various threads for guidance. The Megasquirt documentation is starting to be a little less daunting as well.

More to follow.

Cheers
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
User avatar
Rat
Photo Gallery Admin
Photo Gallery Admin
Posts: 15456
Joined: Fri Oct 21, 2005 9:59 pm
My Album: https://www.ngwclub.com/gallery/v/wingmans/rat/
RIP: cookie
Location: Toronto .... Canada

Re: 1985 GL1200 Limited ECU Replacement/Upgrade

#13

Post by Rat »

Whew .... and I thought the 4 carb system was complicated ....

Gord :shock:
"I'd rather Ride than Shine"
‘14 KLR650 ... not a rat ... yet
‘84 GL1200i ‘R2B6' (Rat to Be 6, the last, adopted by twowings)
My Original 'RAT' was a hybrid '82 CB900/1100F
User avatar
Rednaxs60
Silver Member
Silver Member
Posts: 974
Joined: Mon Nov 30, 2015 11:14 pm
Location: Victoria, BC, Canada

Re: 1985 GL1200 Limited ECU Replacement/Upgrade

#14

Post by Rednaxs60 »

Tuning carbs is a black art as well, and when the carbs go for a walkabout, can be a royal pain.

The interrelation and interaction between the various components is quite simple once you understand the issues. I have to get my head around the trigger wheels and how these interact, pretty much the last piece of the puzzle. Then I'll read everything again, chew on what I have read and understand, then repeat. The more prep work I do the easier the upgrade/replacement.

It seems like a lot, but once you delve into it and commit, not to bad. Keeps the gray matter engaged.

Cheers
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
User avatar
Rednaxs60
Silver Member
Silver Member
Posts: 974
Joined: Mon Nov 30, 2015 11:14 pm
Location: Victoria, BC, Canada

Re: 1985 GL1200 Limited ECU Replacement/Upgrade

#15

Post by Rednaxs60 »

RAT wrote:Whew .... and I thought the 4 carb system was complicated ....

Gord :shock:
I must be a bit off the wall. I find this interesting and fun. Cheers
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
Post Reply
  • Similar Topics
    Replies
    Views
    Last post

Return to “Unique Carburetion”