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I think my NC might be terminal - total loss of power


pmjones79

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SteveThackery
9 minutes ago, sad vampire said:

 

So, fuel supply or high tension electrics is my guess.

 

 

But don't guess - diagnose!  :dielaugh:

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Well, Thanks to all you wonderful people my bike is alive again. Today I replaced the clutch and it did the job. I am chuffed to bits that i finally got there. I had so much help from a

Do you have the "check engine" light on? If yes then find out what the fault code is.   Does it have oil in it?   Do the brakes get unusually hot? Can you push the bike easily in n

… there was an OP?

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The NC has a common integral manifold where the two cylinder exhausts exit at one point from the head, so you can't check the temp of the separate downpipes. 

If the fuel pump was giving up, or somehow the fuel flow was restricted to the point it was struggling to move at any speed, it ought to flag a fault. The ECU will know if it has been trying to richen the mixture on the closed loop feedback, it will have hit the "end stop" or clamped at full rich adjustment and won't have been cycling.

If it has a persistent misfire it certainly should flag a fault.

 

I find it odd that it can run so poorly and no faults are flagged (or at least none have been reported). At least a fault can be interrogated to see what the problem was in principle.

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SteveThackery
11 hours ago, embee said:

The NC has a common integral manifold where the two cylinder exhausts exit at one point from the head, so you can't check the temp of the separate downpipes. 

 

Ah, I'm an idiot!  Of course!  I haven't got an NC any more so I couldn't check to remind myself.

 

11 hours ago, embee said:

If the fuel pump was giving up, or somehow the fuel flow was restricted to the point it was struggling to move at any speed, it ought to flag a fault. The ECU will know if it has been trying to richen the mixture on the closed loop feedback, it will have hit the "end stop" or clamped at full rich adjustment and won't have been cycling.

If it has a persistent misfire it certainly should flag a fault.

 

Yep, agree with all of that.

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DaveM59

TPS? Incorrect signal from the throttle body to the ECU.

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So many amazing people on here suggesting things to try.

The big frustration is the lack of any fault code to steer me in any particular direction.

I ordered an engine compression tester that arrived today. I have the PDF workshop manual so I know that I have to strip almost all the plastics off the bike to disconnect the fuel pump connection as part of the test.

I suppose I have to get in there anyway if I am to check the fuel pump and its integrated filter.

Some of your suggestions say to ride the bike a distance then check things. Unfortunately, with the bike as it is it will not ride faster than walking pace.

I was hoping that the ignition coil test would have highlighted those as the problem. Unfortunately my multimeter isn't the best. Even so, both coils gave me readings for the primary and secondary sides that matched.  Does it say in the manual the expected resistance readings? I can't seem to find what they should be.

I'll hopefully perform the pressure test later today so will keep you posted.

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SteveThackery

This is not me wanting the last word, honestly!  But despite my "brilliant" (:dielaugh:) suggestion of using an infrared thermometer on the exhaust being a non-starter, I would still urge you to take a diagnostics approach (as far as it's possible) rather than just compiling a list of things to "try" and working through them.

The problem with the latter approach is that you might spend lots of time and money on unnecessary stuff before you happen, by chance, across the fault.  Or you might work through the whole list and still not find the fault.

 

Having said that, I admit that the problem with the diagnostics approach is that it requires a better understanding of exactly how it all works.  But honestly, it is the best way if you can manage it.

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SteveThackery

Is there any chance you could post a brief video of the bike on YouTube?  Just starting it up, a couple of blips of the throttle so we can hear how it picks up, and attempting to ride off.  In particular, the exhaust sound and engine sound would be useful, rather than fine camera work.

 

The sound can often reveal a lot of useful information.

Edited by SteveThackery
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When I compression tested mine I was able to get to the fuel pump connector without removing a load of plastics. Might have had to removes a bolt \ plastic grommet ot two, but its just reachable.

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DaveM59
On 18/11/2019 at 22:16, embee said:

The NC has a common integral manifold where the two cylinder exhausts exit at one point from the head, so you can't check the temp of the separate downpipes. 

If the fuel pump was giving up, or somehow the fuel flow was restricted to the point it was struggling to move at any speed, it ought to flag a fault. The ECU will know if it has been trying to richen the mixture on the closed loop feedback, it will have hit the "end stop" or clamped at full rich adjustment and won't have been cycling.

If it has a persistent misfire it certainly should flag a fault.

 

I find it odd that it can run so poorly and no faults are flagged (or at least none have been reported). At least a fault can be interrogated to see what the problem was in principle.

Exactly it isn't fuel, it isn't spark and it certainly isn't compression. It's electrical but not electronic. The bike was running perfectly when the fault occured so it didn't suddenly lose compression, or either coils, or get a fuel or air blockage as that would produce a much more gradual performance drop over a longer period. Plus no fuel would make it hard to start and it would pop and bang on over run. Any mixture irregularities would register an error through the lambda sensor, as would a serious misfire effecting combustion.

The crank sensor must be OK or it wouldn't start and an error would be recorded, same for fuel pressure. Oil pressure would light the warning lamp so what's left?

It sound more like the ECU doesn't know you have opened the throttle so I'd look at the wiring.

Edited by DaveM59
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DaveM59

I assume you have checked that the throttle 'pull' cable hasn't snapped? It may not feel any different at the grip due to friction and the return cable still working, even bunching when you open the throttle.

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Andy m

I had a TPS go on the Hurley-Pugh. The ECU does know because the throttle cable opens the butterfly and the resulting unexpected surge of air ruins the ECU's machinations. The exhaust sensor picks up the variation while the crank sensor does not and the TPS reports sometime along the lines of "It's full of stars Dave" when the correct answer is a number between one and ten. It is true that the ECU does not know if the butterfly has fallen off the shaft or the intake rubbers have dissolved, hence the actual fault code is "TPS sensor reading out of expected range". Chances are this code would relate to a ****ed TPS, but it can't be 100% sure.

 

The misbehaviour starts about half a mile before the ECU runs up the white flag and puts the MIL light on because it tries for a solution to use all that air.

 

I assume the NC has a throttle cable and butterfly, I can't recall otherwise?

 

Andy

Edited by Andy m
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fred_jb

Any chance it could be a blocked breather tube on the fuel tank leading to a reluctance of fuel to leave the tank once a certain amount of vacuum builds up?

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SteveThackery
6 hours ago, Andy m said:

I had a TPS go on the Hurley-Pugh. The ECU does know because the throttle cable opens the butterfly and the resulting unexpected surge of air ruins the ECU's machinations. The exhaust sensor picks up the variation while the crank sensor does not and the TPS reports sometime along the lines of "It's full of stars Dave" when the correct answer is a number between one and ten. It is true that the ECU does not know if the butterfly has fallen off the shaft or the intake rubbers have dissolved, hence the actual fault code is "TPS sensor reading out of expected range". Chances are this code would relate to a ****ed TPS, but it can't be 100% sure.

 

It's not a massive deal to lose the TPS, as it's only used some of the time anyway.  In the absence of a proper MAF sensor (hardly ever used on bikes) the ECU estimates the mass of the incoming air charge using one of two strategies: alpha-n and speed-density.  The former uses the TPS along with engine RPM, the latter uses the MAP along with engine RPM (and air temperature, often).  As a general rule (reality is always more complicated) alpha-n is best at large throttle openings, speed-density mostly at lower speeds and loads.

HOWEVER, you can run the engine on either, so it's normally possible to get home, even though the MIL is on.

I don't know how much effect a faulty TPS has on the NC, but it is certainly a candidate for the reported fault.  I would expect it to light the MIL, though - perhaps you need to run the bike for a bit longer before it reports the fault.

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SteveThackery
6 hours ago, DaveM59 said:

Exactly it isn't fuel, it isn't spark and it certainly isn't compression. It's electrical but not electronic.

 

I think it's too early to be completely certain about that.  I still suspect it's dropping onto one cylinder, hence asking for the video.  The absence of the MIL is something of a mystery and perhaps we shouldn't be distracted by it.

 

6 hours ago, DaveM59 said:

It sound more like the ECU doesn't know you have opened the throttle so I'd look at the wiring.

 

Definitely a possibility, but the ECU can know you've opened the throttle because the engine speed will rise (even with no extra fuel) and - importantly - the MAP will pick it up immediately.  As embee points out, in that circumstance the ECU does have enough information to a/ recognise there's a fault and report it; b/ keep the bike driveable. 

 

So right now I don't think we should be dismissing any possibilities.

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Grumpy old man

Come on man put a video up, we need to get to the bottom of this:yes:

Edited by Grumpy old man
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DaveM59
9 hours ago, SteveThackery said:

 

Definitely a possibility, but the ECU can know you've opened the throttle because the engine speed will rise (even with no extra fuel)

 

I'm not sure it will by much as without extra fuel, as the ECU controls this as a result of the TPS telling it you have opened the throttle, it will just run lean and struggle to maintain revs. There is no MAP sensor.  The exhaust note might be an indicator.

I forgot to connect the TPS on my X9 once and it started and idled fine but had no response to throttle opening and the ECU lamp didn't light. This was a total loss though not a weak or erratic signal caused by bad connection or a failing sensor.

Edited by DaveM59
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SteveThackery
1 hour ago, DaveM59 said:

 

I'm not sure it will by much as without extra fuel, as the ECU controls this as a result of the TPS telling it you have opened the throttle, it will just run lean and struggle to maintain revs. There is no MAP sensor. 

 

Are you sure there's no MAP sensor?  I haven't come across any Euro 3 or up bike without one.  Some bikes don't use the TPS at all at light loads, although I expect the more sophisticated ECU in the NC probably will.

 

I feel frustrated because I no longer have my NC or the workshop manual, otherwise I'd be able to make much more informed suggestions.  To be honest I'd love to get my hands on this bike and dive in, and do a proper investigation.  Unfortunately studying for a Master's takes up too much of my time.

 

We need the video.

 

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1 hour ago, SteveThackery said:

 

Are you sure there's no MAP sensor?  I haven't come across any Euro 3 or up bike without one.  

 

This from the NC700 wiring diagram

5dd67ede7662b_NC700TPSMAP.jpg.22f298dedcb7e36d1c4269ed641efb7e.jpg

 

It would certainly be worth taking the connector off and checking the state of the contacts, I've had experience of tarnished connector pins on my NC.

There is a closed throttle setting procedure for the throttle body so the ECU can learn when the butterfly is closed (needed for idle speed control apart from anything else), might be worth doing that. It involves disconnecting things and shorting out pins, turning on/off etc, the usual sort of stuff. You need the correct procedure for the model year, I only have a 700 manual.

Edited by embee
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SteveThackery

Thanks, Murray, very helpful.  It's a shame the MAP and TPI share a connector, but anyway, it should be straightforward to test them.  I expect the manual will give test specs for them somewhere.

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Graham NZ

All this reminds me of the old saying, "If it doesn't have one it can't fall off or break down."

 

Life was so much simpler when engines had just a carburetor you could dismantle and clean, a magneto with only points to adjust or even a coil ignition system where you could easily carry enough spare parts to replace the whole system at the roadside.

 

Look at the latest BMWs and similar and wonder what joys await their owners when the bikes get old.  Will they become too expensive to repair, their faults too difficult to diagnose, but the bikes still too valuable to scrap?  I fear that all of those things are likely.

 

No wonder many people don't keep their new cars and bikes for longer than their warranty periods.  Maybe that's all the manufacturers want to happen anyway so build them just well enough to get through the warranty period plus a small safety margin?

 

A well known motoring writer here once said, 'If you can't afford to buy a new German car you can't afford to buy an old

one.'  I wonder what he would say about all modern cars and motorcycles?

 

In some ways the modern world has gone tech mad.  My GP spends far more time looking at his computer screen than he does at me.  Have car and bike mechanics become more reliant on computers than spanners?  Heaven (now there is a huge myth) help us all if we can't afford to buy only new bikes.

 

As of November this year HD no longer guarantee to supply parts for Buells.  That should concern me but since my bike was new 12 years ago the only original part needed was a footrest so I think I'll risk keeping it, if just to look at and remember the wonderful rides we've had together.  Yes, it has a TPS which needs to be zeroed occasionally but my simple diagnostic tool can do that easily.

 

Here in NZ it costs five times as much to register an over 400cc bike as it does a car.  A bike over 25 years old is about the same as a car.  Maybe it's time to get one of those lovely old bikes from the 60s or 70s after all?  With modern tyres and suspension bits they may not be too bad even now.

Edited by Graham NZ
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Grumpy old man

Must admit,  I  looked at the diagram above and thought time to.get rid of the NC I just dont understand it all and I don't really trust the people who are meant to do actually do + I can't really afford to use them.😪

Maybe just keep the old Crf at least things are easier to get at.

Edited by Grumpy old man
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Graham NZ

A motor mechanic friend of mine retired early when he no longer understood how everything on cars worked.

 

The WW2 Focke Wulf FW190 fighter had a mechanical equivalent of a modern ECU (or ECM).  No doubt it was a challenge to repair if it took a bullet but anything less was capable of being inspected and dealt with by someone like a watchmaker.  Remember them?  They used to make and repair mechanical clocks and watches.  Big Ben would've been unfixable and scrapped long ago if it was solid state.

 

Like others here like Lloyd I'm pleased with the way the NC performs but dread the time when something I can't fix goes wrong.  Have I ever mentioned that there are 22 weird fasteners to be removed and replaced just to change the air filter?  Yes, I'm sure I have.  The prospect of a fuel filter blockage or pump failure pisses me with dread.  But let's be fair, it's probably only typical of the joys ahead for the owners of most current bikes and cars.

 

If we want more performance why can't we just be provided with bigger, simple engines rather than squeezing outrageous performance from tiddlers.  The more I think about it, HD know more about the sensible way to build bikes than many rides can understand.

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Andy m

This is me diagnosing a TPS on an Enfield. It's pretty much real time only the looking for tools, drinking tea, moving towards the radio when a wicket falls etc. is cut out.

 

 

Changing the TPS is one plug and two screws.

 

Compare this to my CL350 where I have put in hours and hours removing jets and ultrasonic cleaning and every step involves putting it back together and seeing what happens. They gunk up, people change one thing to hide another, parts stick and swell and wear. Diagnosis is by taking it to the local bike cafe and waiting for a coven to form:

 

"You'm be 'avin grunging on thar rockers"

"That no be rocker grunge, it don't smell like gooseberries. Thar be pinking"

"Pinking'd make 'is nose fall off....."

 

The carbs are interesting but only in the way a film camera or record player is.

 

The lack of ability to resolve this is just a skill shortage. It's like asking a blacksmith to fix a computer. We are unfortunately expecting the current generation of blacksmiths to train our programmers so it goes on. Remote diagnostics are the solution and I am guessing are maybe 5 years away on bikes. We have it in small numbers on CV's today.

 

Andy

Edited by Andy m
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Slowboy

I'm with Andy on the skill shortage, but really I can understand the rest of it and the way it works. The biggest issue for me is the cost of a serious diagnostics kit to plug in to allow me to identify faulty components more easily. At the moment that's what slows me down, so I have to measure what I can and do my best to diagnose a fault.

That and Honda UK getting stroppy when I phoned up with the correct part number for the CRF250 Rally workshop manual demanding to know how I got it because "we don't release that information".

It was still worth buying it from the 'states, even though the postage cost me more than the manual (over £80 in total).

If I want the beautiful zen simplicity of morotcycle maintenance, I can always work on the C90.😇

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SteveThackery
10 hours ago, Graham NZ said:

 

Life was so much simpler when engines had just a carburetor you could dismantle and clean, a magneto with only points to adjust or even a coil ignition system where you could easily carry enough spare parts to replace the whole system at the roadside.

 

 

What I would say, though, is that bikes are much more reliable now than they were back then.  I would argue that - whilst Graham is undoubtedly correct - it's really pretty rare for an ECU or its associated sensors to fail.  When they do, and it disables the bike, then of course it's definitely not a roadside repair.  We've gained a lot of reliability, at the cost of much less home-repairability.  We should also acknowledge that a lot of the stuff is there because of emission regs; i.e. not necessarily the "fault" of the manufacturers.

 

HOWEVER, I am totally with Andy on this: there is nothing fundamentally difficult about any of the electronic techie stuff on modern bikes.  All we suffer from is a lack of skills amongst mechanics.  I guess this might be our fault - are we unwilling to pay the going rate for a well-trained tech, so bike workshops use low paid, untrained staff?

 

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