Author Topic: Cold bike takes long crancking  (Read 2386 times)

Jim1988, Scootyman, iNCORRIGIBLE and 7 Guests are viewing this topic.

#20

Offline jm2

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Re: Cold bike takes long crancking
Reply #20 on: 23 April, 2021, 11:01:56 PM
*Originally Posted by MohKraats
... valve clearance has just been done...
I wonder if this is relevant.

Two seconds cranking sounds long but I bet mine takes one second plus - it would need accurate timing (down to 100/200mS) to prove it (both bikes and I'm not sure I have the kit to do it).  Maybe this isn't a problem, more of a 'feature'.

Only do it right - no bodging please.   Keeper of the failed stator list.   John.

#21

Offline Art

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Re: Cold bike takes long crancking
Reply #21 on: 24 April, 2021, 01:39:07 AM
*Originally Posted by MohKraats [+]
Hello Art,

Do you now what criteria the ECM checks before releasing fuel ??

Greez,
Moh

No different to any other electronic fuel system of its age really, sensors etc directly affecting fueling include MAP, TP, IAT, O2, ECT, IDC and IACV.

Have you checked for any stored diagnostic trouble codes? click here for the how to

#22

Offline MohKraats

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Re: Cold bike takes long crancking
Reply #22 on: 24 April, 2021, 02:49:10 PM
Hello Art,

Well, there are a lot of imputs, but the ECM has only a selection of those that have to have a plausible value before it allows starting.

Anyway,

Have had the scope on it to see what it does.
Turns out that when it takes long to start, the ECM doesn`t go into starting mode.
At such moment, injection quantity matches idling.
Normally in starting mode, it throws a lot of fuel in there to get things going.
You see that when starting is normal.

But for some reason after a long stand-still it doesn`t go into starting mode ......
So, it is the ECM that causes this.
Now the big question is, what makes the ECM behave that way.

Greez,

Moh

#23

Online Scootyman

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Re: Cold bike takes long crancking
Reply #23 on: 25 April, 2021, 09:08:00 PM
Hi Moh,

Can you explain exactly what you are seeing on your oscilloscope (waveform) that leads you to believe that there is a Ďstarting modeí. Have you confirmed or read somewhere that this exists on a CBF1000? Itís just Iíve not heard of it or unaware it exists but am open to learn about this if there is one (does anyone know if this exists?)

I have an oscilloscope and I just went out into the garage and connected it up to the injector circuit and couldnít see any difference in the injector waveform on cold start to fast idling warm or indeed a warm start. Are you saying you are seeing a different voltage on cold startup or different time event i.e the injector operation interval is longer or shorter on a cold start? (I might have misunderstood you here)

I donít see the wave form changing or Ďdumpingí extra fuel on a cold start, only the injector operation upon info and instruction from the signal of the ECU & CKP. Tell me what Iím looking for and what you are doing with your scope and Iíll see what I get.

You might see a difference in the IAC reading or on some bikes and scooters a cold start solenoid is implemented which is situated usually on the throttle body (Iím sure youíre aware of this mind)
This is interesting me so looking forward to your reply

#24

Online Scootyman

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Re: Cold bike takes long crancking
Reply #24 on: 25 April, 2021, 09:20:42 PM
By the way, you might want to try and make contact with J-man on here. That fella in my opinion knows his electrical stuff from previous posts I have read and replied to. He might be able to help you.
I take it you are also setting a trigger on your scope to capture the waveform of the injector for both a cold and warm start and then comparing to see any difference?

#25

Offline MohKraats

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Re: Cold bike takes long crancking
Reply #25 on: 26 April, 2021, 07:19:22 AM
Regarding the scope,
I did the most basic measurement here.
Just looking at the injector signal.
See how long it takes before it starts injecting.
There one could very clear see that at a "start" the injector is open at least twice as long during the first one or two rotations.
At a problematic start, it has similar opening time as regular idling.

#26

Offline MohKraats

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Re: Cold bike takes long crancking
Reply #26 on: 29 April, 2021, 06:27:52 PM
Update

I noticed that when at a cold start, I first hit the start button as short as I can,
Then pushing it a second time, the bike starts normal.......... :114:
Weird. :084:
I start to fear it might be a software issue in the ECM.

Anybody any idea ??
Last Edit: 29 April, 2021, 06:52:24 PM by MohKraats

#27

Offline MohKraats

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Re: Cold bike takes long crancking
Reply #27 on: 29 April, 2021, 06:31:17 PM
*Originally Posted by jm2 [+]
I wonder if this is relevant.

Two seconds cranking sounds long but I bet mine takes one second plus - it would need accurate timing (down to 100/200mS) to prove it (both bikes and I'm not sure I have the kit to do it).  Maybe this isn't a problem, more of a 'feature'.

Hello JM2,

Just a question.
How is that with your bike ?
In case cold, you start it, kill it and start it again.
Does the second time just as long crancking as the first time ??

By the way, in my case difference is very clear. Cold bike takes at least twice as long crancking if not longer

#28

Offline jm2

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Re: Cold bike takes long crancking
Reply #28 on: 30 April, 2021, 04:21:41 PM
My bike starts fine.  It has always taken a 'good' start (longer than I would have expected it to).  What I'm saying is, it doesn't "start on the button" i.e. a quick spin-up does not do anything for it at all, but it always starts if I leave the starter running for (estimated) 1-2 seconds (maybe nearer 1 sec).  After this time of ownership I have trained myself to hold the starter on rather than releasing early.

I've never needed to try two starts (cold) but again I don't release the start until I think it'll run.

I am aware that it can be fussy if stalled warm and then a little throttle is best to restart it on those occasions.
After winter I do 'clear it out' (fuel cut off by wot) before going for a real start, that works for me.

What little of the trace I can see does not mean anything.  The ECU will as likely wait for the CKP input to run up quick enough and stabilised before any start attempt.  Maybe your starter is spinning slowly (?)
Only comparing (on your scope) with another biffer will you be able to read anything meaningful.

Have you multi-input on that 'scope interface ?
Can you accurately time how long it takes to start cold/warm-hot ?

Only do it right - no bodging please.   Keeper of the failed stator list.   John.

#29

Offline davidjg

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Re: Cold bike takes long crancking
Reply #29 on: 30 April, 2021, 06:14:38 PM
After 6 years and almost 49,000 miles on my MK2 (until I sold it two weeks ago) and having numerous bikes (and cars) over the last 50 years, pushing the start switch for 1 to 2 seconds before the engines  starts seems quite normal. 
Last Edit: 30 April, 2021, 06:19:11 PM by davidjg