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Discussion Starter · #1 ·
Hi,
Info about the bike 2004 non abs, no heaters 74k miles.
New to the forum, as the title says I got a FI light and according to the procedure it's a code 26 left knock sensor.
The bike will run perfect for 40-60 miles/1-1.5 hours then light will come up and from there it will miss every once in a while a beat, but as you drive more and more and more the stutter will happen more often.
When it's really bad it will stutter every two to tree seconds when coasting, when accelerating the stutter is there but not as pronounced and when it's idling it will idle very rough until it stops down.

I have read several entries on the forum and have compiled the following info:
  • try switching sensors from left to right to see if the error code goes to the other side
  • as per manual check the connection on the knock sensor, check continuity to the connector that goes on the ECM, if both are good change the knock sensor... if the problem continues change the ECM
  • code 26 Left knock sensor should not cause the bike to run bad (hence the link to the ECM)
  • ECMs doesn't go bad easily but a lot of forum entries for code 25 and 26 being a bad ECM
I initially thought (before reading about the ECM) it was the FI pump or the pressure regulator.
ECMs for the 04-05 are very expensive (around 1k$) so buying one to discover it's something else is something I would like to avoid.

I tried first changing the spark plugs to see if that would fix the problem but no luck, here is a photo of how the spark plugs I removed looked like

Automotive tire Gear Cylinder Household hardware Nickel


I'm planning on removing the upper fairing as have to change the air filter and once there I'll clean the ECM connections with contact cleaner and hope that fixes the problem.

today I check the voltage and was 14 and above during idle.

tomorrow will remove and test the knock sensor, I saw an entry about how to test the knock sensor, and then reset the ECM to see if that fixes the problem.

I read somewhere on the Forum about the possibility of lending an ECM to confirm I've a faulty unit.
Any help or hints are welcome
 

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Discussion Starter · #3 · (Edited)
Follow on, I remove the top plastics to be ready for air filter change, I did also disconnect the negative terminal and did the procedure to reset the ECM, once I started the bike and wait for it to trigger the fans I notice two things once the temperature reach the point were fans are turn on:

  • I could hear a lot of "clicking" from a relay under the "relay box" under the seat, like a lot, not sure why it did run so many times
  • the bike started to run poorly, like really bad, no FI sign
I'll remove the plastic case from the "relay box", maybe there is a bad contact from one of the relays.
I pull the trigger on a used ECM from ebay.

Will update once I replace the air filter and ECM.
 

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Discussion Starter · #5 ·
Hi @AJ1500, from what I've read if you get the sensor code and works fine then there is no major issue, from what I have read it seems like the engine uses the knock sensor to adjust the fueling and spark timing so if one of the sensor fails then it's possible the machine doesn't run perfect in the sense of fuel economy and power but still will run fine.

In my case the machine runs very poorly once it starts failing.

Today I was reading about the C5 and C25, it's a connection under the seat on the harness for the relays under a box under the seat.
Seems like that connections distributes power to several components included the ECM, bad instances you can see the plastic connector like burnt, I did check (you have to remove a bit of electic tape as the conector it's "hidden" in the tape as part of the harness going to the blue block of relays, my connector look ok, I did remove and apply contact cleaner to all the relay connections and seat them again in the connector.

After that I tried again to start the bike and let it reach the "fan temperature"... it stutter a bit but not as bad as it did yesterday.
Voltage read 14.3 most of the time with some dips into 13.7 when some things are turned on, like the fans or the lights, that's on idle.
The bit it stutter did also carry small dips of voltage into the 13.7 area... I have check around and don't see melted connections or something... but I notice the relay box gets warm.

Today I got my air filter, I'll replace that tomorrow and report, I hope it's not the factory one that has been never changed.
Will also check the voltage supplied to the ECM, seems like bad wiring may cause a drop of one volt or more and can cause the funny behavior .

Fun fact: there is a small cemetery of insects inside the goldwing, bees in particular...
 

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I noticed with mine (the FI light just started coming on about a week ago) when it's cool like on the morning ride to work, no light, in the afternoon it depends how hot it is as to how long it takes for the light to activate.
I'm hoping it's just a failing sensor. I will be taking much plastics off soon as I am installing a sidecar. I have a lot of wiring to do as well as install new triple tree. going to replace my air filter while I'm at it. I will inspect the plug you mentioned, Thanks for that heads up
 

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Discussion Starter · #7 ·
Ok, I replaced the air filter, good luck the previous owner changed the air filter, it didn't look THAT bad, I clean every connector in my way to change the air filter with contact cleaner, inside the airbox things look ok, put everything back together, I did also put a little bit of sea foam and start the bike until it reached "fan temperature", didn't stutter.
Then I ride to the gas station as I was on reserve, add some fuel and drive back home, everything good, everything working perfect, I did even feel like it had more power, very smooth.
Once I got back home I parked the bike and let it reach "Fan temperature" again and then it stumble a bit, a couple of mins, then didn't happen.

I notice the "fuel pump" and the "fan control" relays get really hot, probably they are the main contributors to the warm sensation of the relay box, yet the cables and connectors did look ok, nothing burned.

I tried moving cables to see if it make the problem appear (maybe a broken cable?) with no luck

I guess I'll have to wait for the ECM to come and hope it fixes the problem...
 

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well yesterday on the ride home the light came on right away and then it started acting up spitting and coughing here and there, I noticed once I got off the highway and on the back road and it cooled down a bit it stopped and ran fine again. I checked and it still has code 25.
where did you get your ECM and what did it cost, I'm still hoping I won't need one but guess I better get prepared for it
 

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Discussion Starter · #9 · (Edited)
@AJ1500
bought used ECM from ebay, in my case it was $500 used, around 1k new, but that depends on the year, from my research it seems like 01-05 ECMs are of one type and 06-17? are different.

Also... check with your dealer, from your signature seems like you have an 02, up to 03 honda change the ECM due to issues, you might be lucky to get yours change based on that.

newer ones are cheaper, the first gen are pretty expensive.

2003 unit 2003 Honda Goldwing GL1800 Ecu Computer Controller Unit Black Box Ecm Cdi | eBay ~$500

2008 unit 06 07 08 Honda Gold Wing ABS GL1800A GOLDWING ECU CDI ECM PGM-FI UNIT BOX | eBay ~$250

----------------

in my case it seems like the new to me 2005 ECM fix the issue, the clicking on the relay box when the fans went on was fixed, just a single nice one click.

I'm now thinking that maybe a bad ground or positive line going bad inside the ECM what causes the issue hence the clicking on the fan relay.
 

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glad to hear you got it sorted out, I'm still riding mine, most of the time it runs fine but lately the light comes on right away and it has a tiny surge at idle and will hic up here and there while riding
but other wise id fine. I know I'm about to have it all torn down soon so I'm hoping it will run good till then.
 

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Hi,
Info about the bike 2004 non abs, no heaters 74k miles.
New to the forum, as the title says I got a FI light and according to the procedure it's a code 26 left knock sensor.
The bike will run perfect for 40-60 miles/1-1.5 hours then light will come up and from there it will miss every once in a while a beat, but as you drive more and more and more the stutter will happen more often.
When it's really bad it will stutter every two to tree seconds when coasting, when accelerating the stutter is there but not as pronounced and when it's idling it will idle very rough until it stops down.

I have read several entries on the forum and have compiled the following info:
  • try switching sensors from left to right to see if the error code goes to the other side
  • as per manual check the connection on the knock sensor, check continuity to the connector that goes on the ECM, if both are good change the knock sensor... if the problem continues change the ECM
  • code 26 Left knock sensor should not cause the bike to run bad (hence the link to the ECM)
  • ECMs doesn't go bad easily but a lot of forum entries for code 25 and 26 being a bad ECM
I initially thought (before reading about the ECM) it was the FI pump or the pressure regulator.
ECMs for the 04-05 are very expensive (around 1k$) so buying one to discover it's something else is something I would like to avoid.

I tried first changing the spark plugs to see if that would fix the problem but no luck, here is a photo of how the spark plugs I removed looked like

View attachment 278141

I'm planning on removing the upper fairing as have to change the air filter and once there I'll clean the ECM connections with contact cleaner and hope that fixes the problem.

today I check the voltage and was 14 and above during idle.

tomorrow will remove and test the knock sensor, I saw an entry about how to test the knock sensor, and then reset the ECM to see if that fixes the problem.

I read somewhere on the Forum about the possibility of lending an ECM to confirm I've a faulty unit.
Any help or hints are welcome
Get a new computer.
I'll bet that's the problem.
 
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