Jump to content
CBR1100XX.org Forum
Sign in to follow this  
gharknes

Fault 25 Knock sensor

Recommended Posts

replaced knock sensor and didn't fix it

does anyone know what the ecu actually looks for at 3000revs and what else could be at fault

also can someone tell me what happens if you remove the plug from the knock sensor on a good one, how does the fault show up

I am honestly now at a complete loss with this as to what it could be, the only clue I have is that once when I had a passenger the light stayed out !!!!!!!!!!! for about 15 miles, this fault used to be intermittant and gradually got worse

Has anyone ever open up an ECU, it looks sealed to me but I'm sure there must be a way inside, I want to check all the pins that they have no bad solder joints etc.

Share this post


Link to post
Share on other sites

I first would like to sayI have 0 experience with this problem on the XX

However from expereince have alway's found the ECU & similar are silicon filled making it nearly impossible to work on so you might want to consider that in the eqaution.

Share this post


Link to post
Share on other sites

Some thoughts that come to mind.

1. Have you done the wiring loom fix yet? Have you cleaned the battery connections and ground connections?

2. Could it be PCIII time?

Share this post


Link to post
Share on other sites
Some thoughts that come to mind.

1. Have you done the wiring loom fix yet? Have you cleaned the battery connections and ground connections?

2. Could it be PCIII time?

will a PCII or III negate the need for a KS ?

Share this post


Link to post
Share on other sites
Some thoughts that come to mind.

1. Have you done the wiring loom fix yet? Have you cleaned the battery connections and ground connections?

2. Could it be PCIII time?

will a PCII or III negate the need for a KS ?

I don't know if the Power Commander uses input from the knock sensor or not, sorry. However if you have a PC, then you won't need the ECU. If you find something wrong with the ECU, then a PC becomes a viable option. However I do see XX ECU's on eBay fairly regularly.

Share this post


Link to post
Share on other sites
Some thoughts that come to mind.

1. Have you done the wiring loom fix yet? Have you cleaned the battery connections and ground connections?

2. Could it be PCIII time?

will a PCII or III negate the need for a KS ?

I don't know if the Power Commander uses input from the knock sensor or not, sorry. However if you have a PC, then you won't need the ECU. If you find something wrong with the ECU, then a PC becomes a viable option. However I do see XX ECU's on eBay fairly regularly.

wrong!!!!, you still need the ecu and it does not have on the pc2 any changes for the knock sensor.

You will need to do the wireloom fix!!!!!! Or at least clean. It is your problem ok???

Share this post


Link to post
Share on other sites

I have done the wiring loom fix a year ago and have recently checked it, my fault is very specific, it is not random like the loom problem, it is a steady 25 blink error that is triggered at 3000revs, although the fault didn't begin that way, at the start it may have been OK for hours then appeared - very much intermittant, now it is not intermittant, I am reluctant to spend money on a knock sensor right now as I'm only 50% convinced that it is faulty, an offer was made to post me one from a member here but the postage was $80, postage from the UK about $20 recorded, I'm pretty sure there are cheaper reliable ways to post a small item like this, I have posted from the US using airmail who will send small package very cheap - about $17, I think I will wait and see if I can convince someone here (Thailand) to let me try one from their bike, will keep looking.

Share this post


Link to post
Share on other sites
I have done the wiring loom fix a year ago and have recently checked it, my fault is very specific, it is not random like the loom problem, it is a steady 25 blink error that is triggered at 3000revs, although the fault didn't begin that way, at the start it may have been OK for hours then appeared - very much intermittant, now it is not intermittant, I am reluctant to spend money on a knock sensor right now as I'm only 50% convinced that it is faulty, an offer was made to post me one from a member here but the postage was $80, postage from the UK about $20 recorded, I'm pretty sure there are cheaper reliable ways to post a small item like this, I have posted from the US using airmail who will send small package very cheap - about $17, I think I will wait and see if I can convince someone here (Thailand) to let me try one from their bike, will keep looking.

Ok, lets try something else. Next is the connection to it and the ecm. if good, then are the wires good form one end to the other, mesure resistance. The wire loom fix consist mainly of ground wires. some are conected together and then again other are not conected to other ground wires. if the resistance is high it will think there is a problem.

Have you read the book on the way the knock sensor works?

It seams to be two wafers of metal in contact with electrical voltage across that become less in contact when knock occurs reducing voltage which reduces timing. I would think you could short across the conection at the knock sensor and there would be no reduction when it knocks.

Are you sure you are not having knock???????

You should be able to mesure the resistance across the sensor and vibrate it and see reduction. Just set on some thing that has vibration. Tap on it.

If you jump the wires and see the light it is in the wires.

Make sense?????

Share this post


Link to post
Share on other sites

Have you cleared the memory? Just so you know that it is a current promlem and not one from memory. I have a '99 that had a Knock Sensor and a IAT sensor signal. I cleaned both terminals with contact cleaner, cleared the memory and it is fine now.

Share this post


Link to post
Share on other sites
Have you cleared the memory? Just so you know that it is a current promlem and not one from memory. I have a '99 that had a Knock Sensor and a IAT sensor signal. I cleaned both terminals with contact cleaner, cleared the memory and it is fine now.

all the cables etc are fine, if I had some idea of what the ecu is looking for at 3000revs I might have a chance of a diagnosis, it could be many things but in order to fault find you need to know what is missing or present when it shouldn't be, my guess is that the ecu is looking for knock signal from the sensor at 3000revs with a certain throttle position etc etc and isn't getting it, this could be the timing is perminantly retarded, not sure how this could happen as the ignition timing is run directly from the ecu to the coils/plugs, also the throttle pos sensor may not be giving the correct information so the ecu thinks conditions are different to what they really are, there just isn't enough information about this to do any meaningful diag, there are no honda dealers out there so you understand my options are limited. It could simply be a faulty KS but I know someone has the same problem as me and has already replaced it and it was still showing fault 25, and yes I have reset the ecu memory several times, the fault is cleared then shows up again at 3000 revs, FI light come on permanently and kick stand shows fault 25, the KS is a generating device it has no power supply, it gives out a signal when knock occurs in the engine, when I read across the signal pin to the body it has no reading I.E. open circuit, not sure if this is correct or not, it would be handy if someone could take the trouble to put a meter across the signal pin and earth to see if same as me.

How many other honda's have a knock sensor ?

Share this post


Link to post
Share on other sites

do you have the book????

lookie

Share this post


Link to post
Share on other sites

yup have it, doesn't say much, check continuity, change ks, if still have problem change ecu

you have no idea how depressing this whole thing is

Share this post


Link to post
Share on other sites

page 553?

21-2

Knock generates to much electricity.

I am trying to figure this out, and am in the process, so don't hold it against me. Some things are comming to me to help you. First you would be able to measure some voltage under vibration, normal operation, from the KS. If it does not gen some, fault, will happen. If it gens some and more happens it thinks knock and retards ign but no fault. I don't think having a fault would mean it is getting voltage. Hence, bad wire, if the sensor is good. Check the wire to the ecm from the sensor for conductivity.

Also, mesure voltage, dc I would guess, from the sensor with engine running and rev and note change.

edited

Share this post


Link to post
Share on other sites
page 553?

21-2

Knock generates to much electricity.

I am trying to figure this out, and am in the process, so don't hold it against me. Some things are comming to me to help you. First you would be able to measure some voltage under vibration, normal operation, from the KS. If it does not gen some, fault, will happen. If it gens some and more happens it thinks knock and retards ign but no fault. I don't think having a fault would mean it is getting voltage. Hence, bad wire, if the sensor is good. Check the wire to the ecm from the sensor for conductivity.

Also, mesure voltage, dc I would guess, from the sensor with engine running and rev and note change.

edited

That looks like a different manual than I have, mine doesn't mention anything like that, the signal the ks generates cannot be read on a meter, you need a scope, btw, I have worked in electronics for years, i do know my stuff, the wire from the ks to ecu is fine

thanks for taking the time to help, what i really need is another bird to do some compares and swapping

Share this post


Link to post
Share on other sites

Your missing that the manual I am talking about is in the link I posted and available for download for you to have, and the pages describe the the function and test.

do you have the book????

lookie

lookie lookie lookie clickie clikie read read right click and save as ok????

Share this post


Link to post
Share on other sites
Your missing that the manual I am talking about is in the link I posted and available for download for you to have, and the pages describe the the function and test.

do you have the book????

lookie

lookie lookie lookie clickie clikie read read right click and save as ok????

I have the full manual but I never saw the quote you typed, I will download the other one, they are the same size and look identicle, will let u know

Share this post


Link to post
Share on other sites

OK I have the same manual, the point here is that the ecu detects a fault in the sensor, so everything will be down because the ecu decides to switch the engine into a safe mode, so the symtoms of having a fault are, low fuel consumtion - low power etc etc....try and understand that the primary problem I have is.....the ecu detects an error in one of the sensors it relies on for normal operation, so the effect of that is ......I get an error flag and the engine performes like a 250cc only using twice as much fuel, this is no good BTW, i run the risk of piston wash..........an over rich mixture for a long period of time will damage my bike........................I blame Honda for all this shiiit, they need to let out a little more info about their diagnostics, especially something so critical

maybe in a few weeks I will post here that I replaced the KS and it fixed the problem....but I reallly would not bet on it.................I worked for years in motor sport (cars) tuning engines etc etc, I am very familiar with ecu's and FI, and even turbo's, did my own setup on my own race car, but it is impossible to fault trace without some information as to what the fault actually is ..apart from a flashing light there is no real info on what has actually failed or what the test is doing and what it expects to see based on certain conditions

Share this post


Link to post
Share on other sites

I had this same problem. I don't know what I did to fix it.

I did the loom fix this did not help

I charged the battery this did not help

I did this at the same time. clean the battery post clean the ground, and change gas and run some Seafoam through it. very high ratio one can to two gallions. I ran it at 100 to 110 mph for about 30 miles. ran 10 miles at 80 back home, next day I fill it up put in another can of seafoam ran about 150

I don't know if this fix it or not the FI light may come on later but for 200 miles it has not.

I may have got some bad gas or the injector got stop up??????

When I was having this trouble most of the time the FI light would come on whit in 1/2 mile or less.

now it has not come on, I rode 80 miles today no FI light.

If the engine may have been knocking because of bad gas?????

try this let us know if this helps, Ron

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...

Important Information

Terms of Use