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My V7 has developed a "stutter"

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AureusGriffon View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AureusGriffon Quote  Post ReplyReply Direct Link To This Post Topic: My V7 has developed a "stutter"
    Posted: 28 Mar 2018 at 08:03
Hello all!

I've just recently joined the Guzzi club, and indeed the motorcycle lifestyle itself. About a month ago now I picked up a 2012 Guzzi V7C in black with around 13,000 miles on the clock. It is, by all accounts, a gorgeous and perfectly capable first street bike. I'm absolutely in love; I don't think I could've made a better decision and I jump at any excuse to ride. Anyway, on to the stuff I'm here for: 

Yesterday, as I was riding onto main campus in the morning, I noticed that the bike was not idling very well. It seemed like it was missing some fires (misfiring, for those of you without an ass-backwards vocabulary). I figured that, since it was a bit chilly out and the ride was very short, the bike hadn't warmed up enough. I rode a bit further after classes to a cafe and the problem persisted. I remedied it by adjusting the "choke" a bit towards the "leaner" direction, which solved the problem temporarily. By the way, I've gathered through looking at other threads that this "choke" is actually just a throttle adjuster and not a real choke, but if I'm wrong someone please correct me, as I only have experience with carburated bikes. 

Today, I went on a longer ride (about 25 miles) and I began to feel a very worrying stutter while the bike is under power, and the idling has gotten worse, to the point that the "choke" doesn't help much at all. It feels as if the bike is bucking each time a cylinder misfires, and its severity ranges from highly noticeable to downright bothersome and distracting. I certainly won't be able to ride with this issue, and that sucks. 

I pulled the sparkplugs and they're quite black, so I've ordered a pair of iridiums. I have a suspicion that they aren't the issue, considering how rapidly the problem worsened and the fact that the old plugs really aren't that bad. I'm definitely not afraid to get more mechanical with my limited toolset here at the dorm (I actually love working on bikes), but I don't really know where to start. I'd really appreciate any insight or experience ya'll might have regarding this issue. I want to get back out there as soon as I can. 

Thanks for the help in advance!
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BobV7 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BobV7 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 2018 at 08:17
Sounds electrical to me so probably best to start with that. Sorry, can't be more specific.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote motomike1400 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 2018 at 14:13
I have a V7C, 2010 model. The choke...which really isn't a choke as such, just opens the throttle a little...is only ever needed on a really cold start, ie below 2'C. Maybe a little throttle once the motor catches. Certainly don't ride with the 'choke' on. Don't think that would cause sooty plugs though, as it's just a fast idle lever akin to having the throttle partially open.
Others have had trouble with lambda sensor...could try disconnecting that...search forum for that.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 2018 at 15:20
Yes, worth disconnecting the O2 (Lambda) sensor, it's a four way connector. Can't remember if your model has one or two.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Vegas Pete Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 2018 at 16:51
Hmmmm...... a V7c with idling issues?  Where have I heard this before?

The black plugs are trying to tell you that the mixture is way too rich.  Unless the temperature sensor is telling the engine control module it's -40 degrees outside when it isn't.... or the Lambda sensor is putting out some really bad info.... or both injectors decided to fail at exactly the same time, and in exactly the same way,  the problem is most likely the ECM.  While the symptoms are not an exact match, my 2010 V7c has been doing stuff like this since new, and I haven't been able to excorcise  the gremlin yet.  Tried the Lambda disconnect- about all that did was give me an intermittent check engine light.  For me about all that's left is to change out the ECM, but that sounds a bit pricey and it's still rideable so far.

By the way- does anybody know if the temp sender signal is analog, and if so would shorting the sensor output to ground tell the ECU it's colder outside than it actually is?  If so, this could be the cause of your issue.

Vegas Pete.
2010 V7 Classic, 2005 Ural Gearup, 1980 Yamaha DT175, 1973 Rokon RT-140, 1969 Rokon MkIII
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AureusGriffon Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 2018 at 18:31
For what it's worth, the temperature guage on the dash is showing correct values. I'm going to try to disconnect the Lambda sensor to see if that is the issue. I do hope the issue isn't with the ECU; I'm going to try out GuzziDiag and see what that tells me before just replacing it entirely if it comes to that.

I appreciate the help!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 2018 at 18:43
The temp sender increases in resistance with cold, reduces as it gets hotter. This is the sender in the air intake, and isn't the same as the one displayed on the dash.
 
Guzzi do seem to overcompensate for cold weather in my limited experience. Certainly fuel consumption increases dramatically in very cold weather.
 
What I did on my Norge is put a 20k resistor in parallel with the sender, which has the effect of making the ECU think it's warmer than it really is. Due to the curve of the resistance against temperature, it has no effect when the engine warms up a bit, or in hot weather.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 2018 at 18:44
But most of the low speed issues with all the newer Guzzi models is down to a weak mixture as a result of all the emissions regs. So getting a sooty plug would suggest it's not just the fuel map.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BobV7 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 2018 at 19:36
I didn't have the severe symptoms that the OP is suffering but I disliked the way my V7 felt at low speeds and at a constant 70 mph the engine seemed to pulse which wasn't very nice either. After a data check on it that didn't find any problems it seemed like it was all down to emmision regs. I have fitted a FatDuc O2 thingy which is what you can do if you are not Brian but just electronically clueless. This has worked for me as the bike warms up quicker, feels much nicer and is still on the same settings it came with. The engine warning light comes on occasionally but soon goes away and after 5 years I won't be taking it off any time soon. Still sounds to me that the OP's problem is in the electrics and some component has broken down or a connection is shorting.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Andyb Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 2018 at 20:06
After disconnecting the lambdas, which I would leave disconnected, it may be loose spark plug caps. Look for signs of arcing on the plug tops
Good luck
andyb
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Post Options Post Options   Thanks (0) Thanks(0)   Quote johnno Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 2018 at 20:22
Don't forget the simple first battery connection tight , I doubt it also but that's always my first point of call
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AureusGriffon Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 2018 at 21:14
So I've disconnected the lambda (there's only one sensor on my model) and it seems to have cured the stuttering while under power. I will have to take a longer ride to confirm for sure. It also helped the rough idle a bit but it returned, albeit manageable.

I'm looking to solve this problem entirely so I'm still going to investigate the ECU.

Originally posted by Andyb Andyb wrote:

Look for signs of arcing on the plug tops


What signs should I be looking for? Sorry but I'm a novice.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 28 Mar 2018 at 22:41
Run the engine in a dark place. You will see arcing.
 
Have you fitted the new plugs yet? Don't even think about going into the ECU until you have checked all other possibilities.  But make sure there is a good earth to it. Dodgy earth connections can cause all sorts of problems.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Cylvabirch Quote  Post ReplyReply Direct Link To This Post Posted: 29 Mar 2018 at 07:52
I would suggest removing the spark plug caps, clipping the leads back by 3mm and fitting new NGK plug caps. It is also worthwhile checking and adjusting the valve clearances properly when the engine is cold. Use the clearances for Europe .008 inch (0.2 mm) for inlet and exhaust rather than those recommended for USA.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Andyb Quote  Post ReplyReply Direct Link To This Post Posted: 29 Mar 2018 at 20:28
Arcing will leave black sooty deposits, there is a known problem of the plug caps coming loose on the plugs. Good advice from the others about cutting back the HT leads etc

If the problem has gone with the lambda disconnected then you can totally remove it and put a staibless steel bung into the socket where it was - available on ebay. I have a slightly later engine with 2 x TBs and it runs much better without the lambdas.
Andyb
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