Theory On Our "Stalling/Stumbling" Issue

[Roger 04 RT]

man you got it bad, mine use to be difficult to hold at 1900 rpm. Does it splutter when cold? Does it miss with roll on / off throttle? Have you got Pulstar plugs to put in it? Has it ever been on the MOSS or OSS tool? If you cant get to a OSS Tool, do the Pulstar plugs and bigger injector, then I will help you rest adaptive learning etc.

Ok here is proof that voltage has nothing to do with the stumble factor.
A 2014 Strada with 3350 km on the clock and a very good fully charged battery, possibly the worst case of a stumbling bike I have ever seen.
This is right after an ECU Reset, warmed up to normal temperature with fan in/out twice, but nothing seems to make any difference to this bike.
Hot or Cold, 3 min warm up or not, fitted with Wuka or not, Dyna-Boost on or off, whatever I do this bike is a full time stumbler.
Riding it is a nightmare, it is on normal 16/47 gearing so in traffic the clutch has to be slipped to keep it above 2500 rpm or it dies constantly.

Cheers, MH

Mark, try a test and reduce the fuel in your PCV 0, 2 and 5 degree columns to 0 added fuel from 1000 to 4000 RPM. See if that improves it.

 

[hasenpfeffer]

Roger, that's not Mark's bike, just someone he's helping. I don't think he has a PCV.

 

[Mark_H]

Roger, that's not Mark's bike, just someone he's helping. I don't think he has a PCV.

Like he said !

As a standard bike it has run like this from day one. We have no Dealer, no MOSS, no GPR 911, no nothing.
Even fitted with Brisk Plugs it still does this.
The bike rides great except for the stumbling around 2000 rpm and if you avoid the rev range by either slipping the clutch or powering straight through it the engine is smooth all the way. It ticks over reasonably well too.

I have read the many posts on the theory of this stumble, throttle body fuel wetting etc etc but somehow I am not convinced they are wholly correct.
This bike is an example of a perfect stumbler and riding it around I can actually get it to fluff and stall any time I want to just by holding it at 2000-2200 rpm, just like I did in the video. I believe other bikes that stumble have the same issue but maybe not quite as bad as this one.

So can anyone explain why it does this ? It should have the same fuel map as any other 2014 Strada.

The bike is now fitted with a Dyna-Boost and goes like a scalded cat, the stumble is less apparent now, but it is still there on occasions when the bike is hot in traffic.

 

[WayneC]

The stumble is a firmware issue and you cant predict what firmware would be fitted to a machine as delivered as it depends on the predelivery done by the dealer

There can be other maintenance factors in low rpm problems but not the 2000 rpm aspect, fitting aftermarket ECU spoofers/PCV etc are stop gap at best

 

[Mark_H]

The stumble is a firmware issue and you cant predict what firmware would be fitted to a machine as delivered as it depends on the predelivery done by the dealer

There can be other maintenance factors in low rpm problems but not the 2000 rpm aspect, fitting aftermarket ECU spoofers/PCV etc are stop gap at best

Surely the firmware is ex factory and not dealer. I am pretty sure the dealer who sold this bike did not have a fully functioning MOSS at that time anyway.
This bike is a 2014 model and should have a later firmware than mine but it runs crap. I know one other bike bought same time as this one from same dealer runs totally differently, how is that ??

 

[WayneC]

Surely the firmware is ex factory and not dealer. I am pretty sure the dealer who sold this bike did not have a fully functioning MOSS at that time anyway.
This bike is a 2014 model and should have a later firmware than mine but it runs crap. I know one other bike bought same time as this one from same dealer runs totally differently, how is that ??

No, normally the ECU's are supplied with either no market firmware or original default firmware, the Dealer then does the upgrade to the current revision as part of predelivery. When I looked at the predelivery schedule for the Terra/Strada available on line I noticed there was no mention of confirming the machine was properly operational using diagnostics or anything of that order and it became clear to me the dealers were unprepared for this type of machine. There will have been Dealers who understood the processes and they would have been the combined BMW/Husky Dealers or those who had been exposed to programmable systems previously
It may be the Dealer did one machine and omitted to do the other, we can only guess but the first step is determine the firmware revision in the defective one

 

[nev..]

So can anyone explain why it does this ? It should have the same fuel map as any other 2014 Strada.

Anecdotal evidence (from multiple threads on this forum) would suggest that people who live close to the equator have the most problems Philippines/Darwin/Florida. Probably due to the climate/heat/humidity ?
I think TR650 owners in cooler climates, Europe, South of Sydney AU, north of San Francisco, have fewer, if any, issues.

 

[johnsweet]

Anecdotal evidence (from multiple threads on this forum) would suggest that people who live close to the equator have the most problems Philippines/Darwin/Florida. Probably due to the climate/heat/humidity ?
I think TR650 owners in cooler climates, Europe, South of Sydney AU, north of San Francisco, have fewer, if any, issues.

exactly, no issues with my machine, 2013 purchased in CT, ride in ME. Latitude 44.335788, Longitude -68.319361, mapII, an ocassional random stall in warmer weather, bone stock, soon to install oz unifilter

 

[kiwiape]

Anecdotal evidence (from multiple threads on this forum) would suggest that people who live close to the equator have the most problems Philippines/Darwin/Florida. Probably due to the climate/heat/humidity ?
I think TR650 owners in cooler climates, Europe, South of Sydney AU, north of San Francisco, have fewer, if any, issues.

New Zealand ain't near no equator.......

 

[nev..]

New Zealand ain't near no equator.......

The tropical cyclones don't seem to know that

 

[mag00]

The tropical cyclones don't seem to know that

It's science. Your toilets swirl backwards. The Husky was made in the Northern Hemisphere and tuned to Northern Hemisphere physics. Anything not in the Northern Hemisphere is not gunna swirl the same through the intake and exhaust. Talk about a finicky system.

Would ja look at that, I just solved the tuning issue, LOL.

 

[mag00]

For the TRs... We really need to hack the ECU code or this could go on and on and on. Or maybe just get a PC5 with AT!!

Rant
And I wish people would stop peddling their own wares and let the products speak for themselves. Before putting shit on other fixers. (CH Sponsors Excluded) My Mickey mouse BP is doing just fine thanks


Anyhow that's my take,

PC5 real cheap in classifieds the other day. Microsquirt development...

 

[WayneC]

As with "Fuels ain't Fuels", the same applies with programmable firmware devices. Rule 1 is know which version you have

 

[Mark_H]

As with "Fuels ain't Fuels", the same applies with programmable firmware devices. Rule 1 is know which version you have

Yes but, like I said....with no access to MOSS, OSS or anything else, 1) How would we tell and; 2) What can we do about it anyway ?

By the way.....we reckon we have fixed the crap running bike I posted the video of, and not with any fancy software either!

 

[MotocycleWriter]

My bike is usually rock solid but was experiencing a good bit of stumbling today. Only difference was lower temperature and lower humidity. Much lower on both counts. I flipped my Wuka King dual mode switch to Low Temp and it seemed to help. Still not perfect...

By the way.....we reckon we have fixed the crap running bike I posted the video of, and not with any fancy software either!

Do tell!

 

[Mark_H]

My bike is usually rock solid but was experiencing a good bit of stumbling today. Only difference was lower temperature and lower humidity. Much lower on both counts. I flipped my Wuka King dual mode switch to Low Temp and it seemed to help. Still not perfect...



Do tell!

The fix is theoretical at the moment and I have to wait until I can get home to my bike in a week or so and get some tests done.
Theory is based upon finding out when the nasty little purge valve is actually opening and causing the change in mixture going into the throttle body.
Basically on that bike we disconnected the purge valve and plugged the hose, suddenly all is fixed and it runs like a dream.
The owner was on the verge of dumping the bike, but now he is riding it like he stole it and enjoying every minute of the smooth power and no stalling which he never had before.

 

[MotocycleWriter]

The fix is theoretical at the moment and I have to wait until I can get home to my bike in a week or so and get some tests done.
Theory is based upon finding out when the nasty little purge valve is actually opening and causing the change in mixture going into the throttle body.
Basically on that bike we disconnected the purge valve and plugged the hose, suddenly all is fixed and it runs like a dream.
The owner was on the verge of dumping the bike, but now he is riding it like he stole it and enjoying every minute of the smooth power and no stalling which he never had before.

The symptoms in that video do not appear to be software. I'd have staked my reputation on a sensor or controller element somewhere in the control loop.

What's the purge valve supposed to do and where is it located?

 

[big-t]

The fix is theoretical at the moment and I have to wait until I can get home to my bike in a week or so and get some tests done.
Theory is based upon finding out when the nasty little purge valve is actually opening and causing the change in mixture going into the throttle body.
Basically on that bike we disconnected the purge valve and plugged the hose, suddenly all is fixed and it runs like a dream.
The owner was on the verge of dumping the bike, but now he is riding it like he stole it and enjoying every minute of the smooth power and no stalling which he never had before.

My guess is something else is causing a rich condition and plugging the purge hose is effectively leaning the mixture.The purge valve is quite active on this bike.Here are a couple screen shots from my o-scope of the purge valve in operation.

(of course there is always the possibility the purge valve was stuck open on the bike in question)

This is at idle,green trace is injector and yellow is purge valve,sorry about the line hash and the cutoff tops ,I was only interested in the "on" time

and at 3k RPM

 

[kiwiape]

Where is this "purge valve"?

 

[hasenpfeffer]

It's on the right side just behind the frame rail above the valve cover. It's only on those bikes with a fuel vapor emissions canister.