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On-Off effect - Fuel injection

clentbiker

clentbiker

Just got it firing!
Joined
Apr 21, 2009
Messages
20
Location
Worcestershire
Does anyone else experience this 'on-off' effect when riding the bike. I have noticed that when I am just riding at a steady speed, neither pulling or shutting off, it feels like the engine is about to missfire and cut out.

Is this something to do with the EU emission regulations.

Can something be done to reduce this sensation.
 
What RPM range?? I've noticed surging when running steady speed, small throttle opening, RPM range 3500 + or -.

Dr. Jason Speaker just called to say he finished the surgery (cam recall) on the Stelvio, and uploaded the new fuel map, balanced throttles, and reset the TPS to Moto International specs (3.5 degrees at idle) Can't wait to see if the popping is gone (TPS) and the surging is gone or diminished (new map). I'm picking the bike up this weekend and riding to the Appalachian rally in SE Ohio. I'll report back with impressions.
 
clentbiker wrote:
Is this something to do with the EU emission regulations.
Can something be done to reduce this sensation.
Click to expand...
Yes, see above... or hopefully we'll have a solution in the near future.
 
the updated fuel maps helps a lot..

to get rid of the surging completey, I wrapped a elastic hair 'bobbin' around the bar, between the throttle grip and the bar end weight, to add a bit if stiction to the throttle. this prevents tiny movement, and worked like a charm to eradicate the surging.

for what its worth I think the inbalance of the controls is the weakest part of the stelvio. The combination of the throttle (too light), clutch (too heavy) and brakes (wooden) takes a bit of getting used to. brakes that need a good pull combined with an over-light throttle is not a great mix for your right hand, especially as you need to blip the throttle as well to get a smooth downshift as well..

My 12 year old Triumph tiger is light years ahead of it in this respect (and has better mid-range). The stelvio does handle well though...

Anybody agree?
 
I appear to be getting exactly the same. Have done 600 miles and the bike when running at a steady 30/40/50/60 appears to be hunting. It's as if a plug lead or plug is breaking down. Didn't notice the same with both the demos I rode so will see what the 1st service the week after next reveals.
 
It realy is uncomfortablle when in traffic and in 30/40 zones trying to keep a steady pace. The Dealer said that this is due to EU emissions and sugguested that I keep the revs up and use lower gears.

I will try as see how it goes.

Reading all of these issues that Stelvio owners seem to be experiencing I am beginning to wonder whether I should put some miles on the clock and get rid of it.

Shame really as it's a fab riding position, sounds great and grunty and also looks good.
 
Hi Gang

It sounds like an ecu issue:(
I have ridden 3 different Stelvio's and the fueling has been sweet on them all:)
I know there have been a few issues with the bikes but mine is smooth in any gear at any speed, no snatching or lurching.



Loftyjohn
 
I've notice the surging from day one. Can't keep it running smooth at any speed. I'm taking it in for the cam recall next week. I'll definitely mention the fuel map upload and anything else I can get the service guy to look at. It is also due for the first service. I wonder if they'll charge me for that??
 
It's often been argued for the 2V motors that the ON/OFF effect can be reduced by removing throttle cable slack.

As far as I'm concerned there'll always be some sort of such effect with a shaft drive lacking a cush drive/buffer. But I thought the 8V models had a modification at that level?
 
Mine has it.

It is positively a fueling issue, lean surge, nothing to do with cable slack or cush drives.

It was very common on the older BMW R bikes.

My understanding of the Beemer problem was:
The O2 sensor is basically a switch. The ECU is adjusting the mixture constantly, and the sensor switches on and off constantly. The surge is the when the mix goes a bit too lean just before it comes back. So you feel this in the engine power as you cruise along.
 
as previously mentioned guys, and bit of stiction on the throttle, combined with no slack in the cables has eradicated it for me, bike runs smooth at any revs, as low as 2K rpm on top if needs be..it is even smooth around the dreaded 3k rpm mark, where it usedto be worst.
I recommend you try it, it doesnt cost anything ( except the bobbin :) )
 
"before it comes back" — the O2 sensor? That could be it, were it not that as far as I understand, the O2 oscillates at a frequency where you wouldn't feel this (= too fast).

However, those older R (and GS) bikes had something that was explained to me as a cut-off in fuel injection when braking on the engine (or simply rolling off). When the fuel doesn't come back in time, you'd get a surge. It's quite conceivable that Guzzi is trying to implement something similar.

Anyway, I mentioned the shaft and cush drive not because they cause the issue (except possible when coasting downhill), but because they absorb it less than a chain would. Try riding on the idle regime in 1st: almost impossible on my Norge. I also noticed that there's a rather clear transition point where the engine goes from pulling to braking and vice-versa, resulting in surges ... until I learnt to compensate with the clutch ;)
 
For me, the new map has nearly eliminated the surging. And, cable slack needs to be removed to eliminate choppy throttle inputs, which can be distinguished from the surging by "on-off" type behavior when moving the throttle, as opposed to the stumbling that occurs with steady throttle input at steady speeds/light load which is the map problem.
 
Just had my recall work done and speedo sensor fixed, but when I asked about getting the new map I was given a very definate no from my dealer :( . Might try your hair bobbin idea Dec, do you have any pics of your mod ?
 
On the other hand, you get this also.

http://www.sparkplugs.com/glossaryImage.asp?imgID=382

The ECU goes lean and waits for the O2 sensor to indicate a lean condition. It then goes rich and waits for the sensor to report a rich condition. The ECU, and thus the sensor output, constantly vary up and down. It can be said that the ECU 'oscillates', and expects the sensor to oscillate with it.

But the sensor alone does not oscillate.

It is tha ECU switching from rich to lean and back constantly that is noticeable on mine at a constant cruise.

But it isn't really a problem. I'll get the firmware update soon and see how that goes.

For me, it is the horrible 33 MPG fuel economy that is the problem.
 
Strange. I remember a discussion with a member on (undoubtedly) the old forum, who'd installed a lambda sensor of which he could analyse the output. I also remember remarks that the O2 read-out on the VSTDTS should oscillate - switch back and forth between 2 levels. Am I mixing things up, is the fluctuating in fact the signal (what's being measured) and not the way the signal is encoded?
 
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