Very odd code 26 problem, might be fixed or something other than ECU

MidLife said:
My understanding was that what was being talked about here was the more common case where the Knock Sensor is NOT faulty but the ECU is falsely coding that it is.
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I won't stake my life on it, but I would strongly suspect that whether the ECM detects a faulty knock sensor or it mistakenly thinks that it has detected a faulty knock sensor doesn't make much difference. In either case it will respond as though there is a faulty knock sensor because it can not distinguish the difference between these two scenarios, so the end result is likely the same.
 
The table in the shop manual indicates that the bike is Ok to ride:

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In my experience with my 06, I never had a fault reported, but it did use to lightly knock ( high pitched, bunch of keys type rattle) when hot, when under load, top of mountain passes, when E10 / E5 fuel was used, hard acceleration.

I didn't rate the ability of the Ecu and knock sensors to detect and prevent this from happening. Maybe the default mapping is to be preferred.
 
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The table in the shop manual indicates that the bike is Ok to ride:
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That statement in the service manual always left me a little perplexed. It has been reported on this site over and over again that when a code 25/26 is present there is a noticeable loss in power and an increase in fuel consumption, which makes perfect sense to me. That does not seem to qualify as the engine operates normally. Maybe it should read engine is safe to operate.
 
'Normal' is how engines used to operate. Knocking was usually caused by either timing being too advanced, or mixture being too weak - ie too much air compared to fuel. (ignoring carbon build up on the spark plugs, and poor colling air flow).

The mixture was more or less fixed - although some adjustment was made by the shape of the carburrotor needle valve which could be raised / lowered so that more /less fuel could be added earlier or later in the throttle position.

And igtition timing was 'fixed' - literally on my Bantam. You had to adjust the contatc breaker postion to a place in the engine revs where you wanted the engine to rattle, and compromise that with acceleration - or lack of. 15 degrees BTDC or something similar, and the plate was locked at that. In reality it was somehwere between the engine rattling like a tin of marbles and forever backfiring.

Later, on other bikes, it was bob weights that increased the spark advance as the engine revs increased.

The idea of feedback from sensors came much after the time I took my last engine apart. IT was probably around at the time, but I had no money to buy electronic ignition kits.
The ST's sensor and computer provide real time data and real time response - so there would be advanatages in maintaining the weakest possible mixture without causing engine knock, as well as performance advantages.

But going back to a 'mapped' setting where the advance and the fuel mixture are controlled by an engine map - is probably far superior to the old methods - but not as good as the real time monitioring.
A map, I imagine, is a lookup table. Obtained from a properly working system x revs, y throttle, z engine rpm -> f fuel mix, g advance. Something like that.

So I would expect not to get the most out of the engine when the sensor is not being read. But the mapping will be much better than the rate of the bob weight advancements with speed.
 
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Mine definitely sounds/feels different when the light illuminates. On my second ECU and just living with staying below 4K RPM. Works for me, YMMV (especially with the light illuminated!).
 
The knock sensor is exactly what it says, a "knock" sensor, what it responds to is the sounds of pre-ignition. Which is a response to early lighting off of the fuel mixture. This can be caused by a hot spot in the combustion chamber, incorrect ignition timing, bad gas or all of the above Carbon build up can raise compression levels to the point where timing needs to be adjusted, but that is rare. With the carbon build up is lower with the cleaner fuel
The meaning behind octane levels is the resistance to controlled ignition. The higher the octane the more control it has on flame travel across the piston top. That translates to a longer ignition event with a slower flame travel, hence the the timing can be advanced and give a longer power stroke. regular has the least control over the event so it has a narrow timing and faster flame travel. this can cause the early ignition to start.
If this bike has set for a extended period of time it probably had bad fuel in it amd even if drained and changed it would take a few miles to wash itself out and go to "normal" operation. It sounds as if your knock sensors ohm out OK they are probably fine and you just need to ride it more, Also use premium gas, I have mixed 50-50 premium and midrange without any problems, although that is my choice and don't recommend it
With a knock sensor failure the ECM wil retard the timing and give you less power and lower fuel economy, the way to check the sensors is to put on a timing light hold the throttle open a bit and tap next to the sensor, the timing should jump a bit.
I don't use fuel additives until I have found out what the failure is, in retrospect I can't remember using a fuel additive. I have used injector cleaner in the early injection systems (80s, 90s and maybe 2000s) but with the deposit resistant coatings that problem has kind of gone away,
With all the variables involved I would not throw an ECM at it with hopes of this fixing it. If you live near a vocational school it can be a good resource for technical information, or which works just as well is find a mechanic that has gone through a good school and ask them to describe it to you.
We love to talk on and on about these things
 
Well I have decide to go with option C. I'm leaving Saturday for a 4000 mile ride. I upped my AAA membership to include motorcycle towing and I'm just going to ride it like a madman and if she blows then oh well. It runs well at 80-90mph with the light on and I'll just stop for more gas. I got it cheap and it will be a good spare parts bike for a 2008 and up model that has less problems and you can still get a new ECM for.

If I learned anything from the teachings of the great Scotty, when he says she just canna take any more Captain, she can take a little more.
 
MidLife said:
My old mechanic still services a few STs and hasn't seen a 25/26 coded one blowing yet.

But then again....none of them ridden by a madman either!
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ECM FAILURE POLL AND DISCUSSION | ST1300 Related

This will be something that is more an more common, already is, as time goes on. I'll use this thread to: 1 - track what category of bikes seem to have the issue - seems obvious the oldest bikes will have this first but maybe not. 2 - track the symptoms (FI codes) and trouble shooting steps...
www.st-owners.com www.st-owners.com
 
Al st1100 said:

ECM FAILURE POLL AND DISCUSSION | ST1300 Related

This will be something that is more an more common, already is, as time goes on. I'll use this thread to: 1 - track what category of bikes seem to have the issue - seems obvious the oldest bikes will have this first but maybe not. 2 - track the symptoms (FI codes) and trouble shooting steps...
www.st-owners.com www.st-owners.com
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I rode it 1040 miles today from st louis to sturgis in 16 hours. I used a jumper on it to get it into diagnostic mode and it did fine.
 
Did 4000 miles total last week with the light on and it was fine, I am still looking into getting it fixed. I have a bad ECU on the way that I am going to cut open and see what might be the problem.
 
When you say it was fine.....I question if you had noticed a difference in MPG, or Heat?
Several bikes that have come through my garage, that have been riding with the light on, were found to have heat damage to a lot of the body work, wire harnesses, sensors, and stuff.
And their MPG dropped a lot.
Just wondering if your observant or not?
 
Igofar said:
When you say it was fine.....I question if you had noticed a difference in MPG, or Heat?
Several bikes that have come through my garage, that have been riding with the light on, were found to have heat damage to a lot of the body work, wire harnesses, sensors, and stuff.
And their MPG dropped a lot.
Just wondering if your observant or not?
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The light came on 100 miles after I got it. It is always hot so not really sure.
 
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