V7 Classic, unreliable idle. |
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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I think that goes for many of us.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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Vegas Pete
Falcone Joined: 21 Nov 2017 Location: Las Vegas, NV. Status: Offline Points: 23 |
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Howdy, all!
I took the advice of the experts here and disconnected the lambda/02 sensor. The first thing I noticed was that the idle seemed a little better and the mixture a little richer. The stumbling idle instability persists, however. I'm also getting an intermittent check engine light- usually a few minutes after starting. Sometimes it goes away by itself, sometimes not. So, it looks like it isn't a fuel mapping issue. Thanks for the input, Vegas Pete.
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2010 V7 Classic, 2005 Ural Gearup, 1980 Yamaha DT175, 1973 Rokon RT-140, 1969 Rokon MkIII
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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The check engine light could well be the lack of the O2 sensor. The ECU will expect an output but not see it.
And just because it's been removed won't always guarantee that the base fuel map is perfect. If the light comes on is there a way you can read the fault code generated?
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Brian.
Better 5 minutes late in this world than years early in the next. |
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Vegas Pete
Falcone Joined: 21 Nov 2017 Location: Las Vegas, NV. Status: Offline Points: 23 |
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Howdy, Brian-
The odds are the light's telling me there is an issue with the O2 sensor. In seven years of ownership the light had never came on until I disconnected the sensor. I have a harness to connect a laptop to the bike, which I think I've used once since I've had the bike. Haven't seen it in years, but I'm pretty sure it's buried out in the garage somewhere. The other option is to take it to a dealer, but the one I've used in the past (350 miles away) no longer exists. The Western U.S. is not what you would call Guzzi-dealer rich. I guess I'll just keep living with it for now, and wait for something to fail catastrophically before making my next move. Thanks for your help and input. by the way, this forum is light years better than the Guzzi forum I belonged to when I first bought the bike. That one was made up mostly of aging frat-boys who didn't seem to know anything but were always looking for an argument. Vegas Pete.
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2010 V7 Classic, 2005 Ural Gearup, 1980 Yamaha DT175, 1973 Rokon RT-140, 1969 Rokon MkIII
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OldJohnboy
Senior Member Joined: 16 May 2014 Location: The Hemingfords Status: Offline Points: 376 |
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Ha ha. Sounds all too familiar! But, as you say, not here. This is my favourite biker forum, even though I don't own a Guzzi at the moment. |
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Mike H
Senior Member Joined: 21 May 2014 Location: East Anglia Status: Offline Points: 8733 |
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Just an idea, but could be a failing ignition coil. Or spark leaking to ground. |
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"Chicken nuggets don't dance on a Tuesday."
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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I don't know the V7 series that well, but there must be a crank position sensor somewhere. These can collect metal swarf on them and mess up the ignition. Worth a check, I'm sure someone will be able to tell you where it is if you don't already know.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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Mike H
Senior Member Joined: 21 May 2014 Location: East Anglia Status: Offline Points: 8733 |
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That's a good point actually. Even a dodgy connector for it could cause a problem.
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"Chicken nuggets don't dance on a Tuesday."
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Adam
Senior Member Joined: 19 Jul 2017 Location: UK Status: Offline Points: 127 |
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Cleaning, checking sensors condition and associated wiring are certainly a good starting point, even renewing them as elimination process if it's not too expensive for you
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Vegas Pete
Falcone Joined: 21 Nov 2017 Location: Las Vegas, NV. Status: Offline Points: 23 |
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Greetings, all!
Thanks for the suggestions- they’re all valid. I’ve isolated and rejected as many possibilities as I can without actually replacing parts. The problem isn’t so much a “miss” as a weak firing stroke. It never fails to fire, it just doesn’t contribute enough energy to maintain idle speed, if that makes any sense. I’ m still convinced it’s not a fuel/air ratio problem or an interrupted ignition issue- to me it’s an intermittent ignition timing issue that affects only one cylinder, and only for a couple of revolutions at a time..... and even then only at full-closed throttle. I did a little Google research and found that the ECU has two ignition channels, one for each cylinder. That would allow one crank position sensor to fire each spark plug separately without using a distrubitor to get the timing right for both cylinders. This would also allow different timing for each cylinder. That would make for a cheap and easy way to stutter the spark to one cylinder for over-rev protection while causing a minimum of backfiring. I’d love to sit down with a Magnetti Martello engineer, buy him a beer, and discuss the inner workings and design philosophy of this ECU. Vegas Pete. |
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2010 V7 Classic, 2005 Ural Gearup, 1980 Yamaha DT175, 1973 Rokon RT-140, 1969 Rokon MkIII
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Adam
Senior Member Joined: 19 Jul 2017 Location: UK Status: Offline Points: 127 |
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Are there two crank sensors or one sensor and two crank magnets?
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Cylvabirch
Senior Member Joined: 02 Jun 2014 Location: Whitehill Status: Offline Points: 274 |
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Going back to basics: have you replaced both spark plug caps with new, genuine NGKs? Dave Richardson was advocating this on a post I read somewhere.
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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I think many of us would love to do that. A lot of problems could be ironed out more easily if we knew more about the inner workings of the ECU. Just one thing, a partly blocked injector could also produce your problem. Have you tried adding some injector cleaner to the fuel?
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Brian.
Better 5 minutes late in this world than years early in the next. |
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Vegas Pete
Falcone Joined: 21 Nov 2017 Location: Las Vegas, NV. Status: Offline Points: 23 |
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Brian-
I'll give it a try.... couldn't hurt anything. Thanks, Vegas Pete.
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2010 V7 Classic, 2005 Ural Gearup, 1980 Yamaha DT175, 1973 Rokon RT-140, 1969 Rokon MkIII
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Mike H
Senior Member Joined: 21 May 2014 Location: East Anglia Status: Offline Points: 8733 |
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You'd probably need to be a computer programmer whizz kid to understand it tho. |
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"Chicken nuggets don't dance on a Tuesday."
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