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Bad misfire california vintage 2008

Andrew Stewart

Just got it firing!
Joined
May 17, 2020
Messages
7
Location
Telford England
After many years of lurking, reading of other people's problems, I've now got one I'm stumped with. I've had my Cal. Vin from new, 2008.Never had a problem with it. Towards the end of last year noticed a bit of a misfire but thought I'd look at it in the spring.
Got it out a month or so ago and when I took it out noticed it missed, sometimes under acceleration, when accelerating again after having slowed and when riding in town. I also thought it was popping back, either through the exhaust or possibly throttle body.
I suspected ignition first so changed the plugs but made no difference to running.
I then changed the coils, leads and plug caps. I did this today. When I tried to start it, it took ages. (it normally starts no problem) When it did start it seemed to miss a lot more than before, and even got some smoke back through left t. b.
I took it for a short ride and it ran very badly, missing so much the tacho needle was bouncing up and down. I rode perhaps 4 miles with no improvement. Once back I removed the plugs. The right hand one was OK but the left hand one was very sooty.
Methinks the problem may not be electrical but fuel.
I'd be grateful for your thoughts. In the meantime I think I will put all the electrical stuff back as it was and drain the fuel out. I have already put some injector cleaner in the tank and done maybe 25 miles, but no new fuel.
Andy.
 
The other possibilities are a faulty TPS, or the TPS needs to electronically reset, or cam position sensor. The P8 manual in the downloads gives you the specification for the cam position sensor.
 
Many thanks for the suggestions chaps. I now have something to look at.
Do the 2 small spark plugs have to be fully functioning and connected?
I, perhaps incorrectly, reasoned that as there were 4 those 2 didn't matter so didn't bother connecting them back to the coils. I looked in my Guzziology but couldn't find any reference.
 
All spark plugs need to be connected. Dual plug engines are timed differently than single plug engines. With one set disconnected you may have damaged the coils as the build up charge had no place to go.
 
The other possibilities are a faulty TPS, or the TPS needs to electronically reset, or cam position sensor. The P8 manual in the downloads gives you the specification for the cam position sensor.

..or minirelays, I change all of these, but the fault was relays. Omron is good replacement.

-KG-
 
I had a sneaking feeling that I may have made a mistake by not connecting up the little plugs. I have already ordered a set, and the leads and caps Togo with them. I'll put the meter across the coils to check them. If no good I still have the original set.
I'll try to put the plug side of things right first but if still not right I'll move onto other bits like the relays. I've aV11 le mans that are renowned for relay trouble.
Thanks both for info.
 
Replaced spark plugs and h.t leads and put it all back together again.
Started straight away and ran smooth. No hint of any misfire. I went for a 10 mile ride with no problems.
I am in love again.
I think I'll get my Griso out again and have even more fun. I've not been able to ride bikes for a few years now, so started messing around with older Vespas. Still Italian but nowhere near as much fun.
Thanks for the help.
AS
 
I had a sneaking feeling that I may have made a mistake by not connecting up the little plugs. I have already ordered a set, and the leads and caps Togo with them. I'll put the meter across the coils to check them. If no good I still have the original set.
I'll try to put the plug side of things right first but if still not right I'll move onto other bits like the relays. I've aV11 le mans that are renowned for relay trouble.
Thanks both for info.


If you didn't connect the inner plugs and left the leads disconnected you have probably fried the coils.
 
I didn't say I didn't believe you,John. I just said they were working OK at the moment
I have no intention of replacing the coils while they are working OK. Don't feel that my actions or inactions are in any way because of a doubting of your obviously extensive knowledge of Moto Guzzi's. There is no slur in tended. In the future it may not be a good idea to look for help on this forum if the contributors are so easily offended.
Many thanks for your help.
AS
 
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