Missing at throttle off 4k rpm - Ducati Scrambler Forum
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post #1 of 15 (permalink) Old 03-26-2017, 07:54 PM Thread Starter
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Missing at throttle off 4k rpm

My Classic just started doing this when hot and then throttle off holding 4k rpm the engine misses like a mongrel. Under acceleration it is fine, driving quietly it is fine only does this after a flogging and throttling off then holding 4k rpm... any ideas? Btw I have it booked into the dealer this week to run diags etc...
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post #2 of 15 (permalink) Old 03-27-2017, 05:37 AM
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No idea, but please let us know what you find.

Sarah

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post #3 of 15 (permalink) Old 03-30-2017, 06:13 PM Thread Starter
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I had the bike into the Dealers yesterday, they ran diag's and adjusted the TPS and it runs sweet. Until again this morning in cool air temp, I had the bike running hard for a fews km's upto 130kph throutled off and around 4k rpm missed and farted around and took sometime to pick up and come good again... I am wondering if a bad load of fuel, rubbish it an injector? as it almost seems like it could be starving for fuel at low revs, as when it has been like this the idle drops right down to about 1/2 the rpms it usually idles at.... Give in a boot full and she is off ....?????
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post #4 of 15 (permalink) Old 03-31-2017, 05:31 AM
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Well it wouldn't hurt to drain the fuel and start with a fresh tank, but you'd think bad fuel would cause it to run poorly at all rpm. A call to the dealer first thing? Did the diagnostic test show a particular fault?

Sarah
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post #5 of 15 (permalink) Old 03-31-2017, 09:35 AM
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Plugs, Leads, HT short ? usually idling at half speed indicates one cylinder down.

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post #6 of 15 (permalink) Old 04-24-2017, 08:03 PM Thread Starter
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Well it was a fuel issue. The fuel filter was buggered, apparently it was a real mess...
I fuel at 2 stations and one or both are culprits. I have decided to refuel at the one with newest tanks . 18,000kms on a fuel filter was a surprise. Anyway all good now and yhe Scrambler is back hitting the local roads. ..

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post #7 of 15 (permalink) Old 04-24-2017, 09:13 PM
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Interesting, I can't see ref to one in maintenance chart, nor spares available anywhere, did they have one in stock or a bit of cunning kiwi ingenuity ?
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post #8 of 15 (permalink) Old 04-25-2017, 02:07 AM
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So low fuel pressure and the ECU didn't throw an error or store a code for the dealer to read? Useless. ...What's the point of the electronics if it can't even do this?
I'll say again - I'd rather chuck the whole shebang and go back to carbs and CDI.
...like most of the Gpz1100 guys did in the 80's.
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post #9 of 15 (permalink) Old 04-25-2017, 05:11 AM
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The ECU has no means of knowing what the fuel pressure is at either side of the filter. It can only know if there is a problem with the injectors, coils, fuel pump or one of the sensors. I'm not aware of any injection system that measures fuel pressure.
With current emissions requirements there is no way you will ever see a bike with carbs again. Modern injection systems are generally very reliable and I for one prefer them to any carburettor. Once you understand how they work fault finding is not that difficult and whatever fuel fecked up the filter would have played havoc with a carburetor set up too, although refilling the tank would probably have fixed it.

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post #10 of 15 (permalink) Old 04-25-2017, 06:08 AM
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As you say - one of the sensors - like one to monitor fuel pressure which I believe is critical for fuel injection. I am pretty sure if my car had low fuel pressure it would throw an error and I could diagnose that via OBD2. Yes manufacturers will always use efi now because of emission regs. I argue that if they do use them, make it more functional rather than a half assed implementation focused purely on emissions. However it is in line with fitting crappy suspension rather than doing it properly just to shave a few hundred off the retail price.
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