Random Stall – a Silver Bullett or as close as we may get. TR650 Husky

The readily available, simple to use, dealer tool.

GS911 will tell you the firmware version, ask around your area and see if there are any BMW owners with one who will beam into the bike and get the info off it for you

My thoughts and experimental results on the 'nasty little purge valve' and its effect !

Having helped out a friend with a very poor running Strada of which I posted a video earlier. That bike was running a Dyna-Boost, Brisk Plugs and had a Cannisterectomy but the Purge Valve was still in place connected up but no cannister of course. We found out that the Purge Valve on that bike was faulty and allowing a small amount of air into the Throttle Body which gave a lean situation and the bike was absolutely crap between 2000 and 2500 rpm. As the video clearly showed, I could even make it stumble and stall just by holding it in that rev range. We took out his purge valve and plugged the hose to the throttle body and suddenly his bike was running sweet as a nut with no stumbles or stalls and smooth power right through the range. Happy owner !

Armed with this information and suspicious of the purge valve being more responsible for the stumble than some here appear to believe, I set about a little experiment using my bike.
Set the bike up exactly the same as his, Dyna-Boost on same setting, Brisk Plugs and the Purge Valve (not faulty) in place connected to throttle body but no canister, basically drawing fresh air whenever it opened.

That is the question - When does the Purge Valve open and how can we tell ?

My bike was running pretty good, no stumbles or stalls but every now and then it went a bit 'fluffy' around 2200 rpm in traffic. Not so bad as it was with the Dyna-Boost disconnected but certainly not quite right. I suspected that the 'fluffy' kind of hiccup might be coincident with the purge valve opening and drawing fresh air into the throttle body.
With this in mind I wired a small red simple LED across the two wires that run to the Purge Valve connector and taped the LED to the bars where I could see it as I rode the bike. I wanted to know exactly when the ECU was energising the purge valve to open.

I started the bike and was surprised to find that the LED was flashing constantly, like a pulsing signal to the Purge Valve which appeared to be almost continuously energised even at tickover. However the flashing LED was quite dim until I opened the throttle when it went brighter, but still pulsed at the same rate. Riding the bike the LED flashed constantly but was dim when the throttle was closed and brighter when it was open especially under hard acceleration.
Then at the traffic lights the motor did its 'fluffy' thing and the LED was very bright, which indicated the valve was fully energised. I repeated this for a few runs and each time exactly the same, LED flashing bright when accelerating, dim with throttle closed and bright again during the low revs 'fluffiness'

Back home I removed the LED, removed the purge valve and plugged the hose to the throttle body, then went for exactly the same run again.
Result - No stalls or stumbles and no 'fluffiness' in traffic either. Try as hard as I like I cannot get it to stumble or stall.

I know the Dyna-Boost works and the really bad stumbles my bike used to have are cured, but now the occasional 'fluffy' revs during traffic are also gone.
I am becoming happier by the day with the bike, especially as I also got my long term oil leak fixed too. (separate post)

Mark_H, Nice experiment! If a couple other riders could cap the purge valve at the TB and see if that improves things you could get further confirmation.

Many ECUs only open the tank purge valve periodically but the Terra seems to open it frequently. A GS-911 log will probably shed some light on that. Perhaps the latest SW update that Wayne has spoken about rewrites the Purge Valve operation.

Thanks Roger - I believe that the purge valve is complicit in the stumbles etc, it may not be the only culprit, but at least I isolated it now.
I would love to see what the recent recall of the BMW GS650 for lean stumbles is all about and do they reflash the ECU etc so it doesnt do what the TR650 clearly does. Is there a purge valve on the BMW and do they stop or reduce it operating ??

On the Motronic and BMSK, the ECU turns the purge on and off once the engine is warm and when the conditions are stable enough for closed loop. On the BMSK, the ECU adjusts idle stepper and fueling to keep AFR steady, no stumbles. The key point is that the ECU on those bikes is very effective in compensating for the additional airflow and AFR change from opening the valve.

Given the other lean-spikes seen in TRZ_Charlie's LC-2 data, I wouldn't be surprised if the MM ECU reacted too slowly to the purge valve actuation but there isn't any data on it. Charlie could make a riding log with the purge valve closed off and we could see if it was better.

It could also be, as Wayne has suggested, that newer software addresses this also. But we'd have to run an LC log on a bike with up to date SW.

I've talked to Bill - he's been incredibly helpful. I was in Oregon to ride and stopped by to chat on my way home; he's even helped me over the phone. He is limited though too since (as I understand it) he doesn't have access to the new or upgraded codes from BMW. Totally worth talking with him and I intend to use his shop despite the trek, if I can't find someone willing to work with me here. May be a big project.

Mine has been capped off for the longest time. Runs fine. But then again, I have a custom single can exhaust, pod filter and brisk plugs, and will upgrade to pulstars next time.

I'm going to throw you some more info to ponder Roger.

I have removed my canistor long ago, and will be putting a spal fan in that space soon. Why? Because the TR650 fan does not come on at the proper times. The fan will not come on until AFTER the motor starts to run warm. If the motor is running warm, the ecu probably makes some adjustments right? I do not know if there is a calibration or setting in the ecu to change this "on" point.

So many drivability issues can be resolved by putting the extra fan on and having it come on when the water temp in the radiator starts to warm up vs waiting until the motor is hot for the fan to kick on. Thermostatic switch in the radiator should do fine, or just a switch and turn it on as soon as your speeds drop.

Some guys are doing the T stat delete, but then you run into a cool running engine and a different set of fueling ignition adaptions.

Just my humble opinions on this

I have had my purge valve off with it caped at the throttle body since day one. I do have the thermostat deleteand I'm running the zip ty coolant. It works great. It still warms up and stays around 5 bars. The fan comes on but for only a short time. The fan use to run way longer before the T delete. I have been in temps in the low 30's and still runs at the same temps.

I had a stall/flameout 2 weeks ago in Mexican Hat Utah.

Roger,

I am just back from SE Asia. Jet lagged still but perhaps next week I can run the log. I need to read this thread better to understand what the gist of this test is though.

ECUs in general do make corrections to fueling and ignition advance based on coolant/oil temperature. Often those changes are most significant when the engine is cold and the fuel is not being well atomized and is condensing on the cold walls of the throttle body, valves and cylinder walls. Fueling AFRs are typically stable once the engine is warm and don't change much with further temperature increase.

It's harder to say what the ECU does to ignition advance with higher air, oil or coolant temperature. High air and cylinder head temperatures can result in detonation, and the ECU might compensate by reducing ignition timing. You could collect before and after mod GS-911 data and see.

A few answers re the Purge Valve

1/ Putting an LED across the two wires to the valve will mean the LED will light dimly when the valve is off, it is operating through the sense circuitry used for diagnostics, I see it on the test bench every time I test an ECU and use it as a quick test to confirm the sense circuit is OK.

2/ Yes all the US F/G Series BM's have the purge valve, they are all the same I/O circuitry in the ECU's, pretty standard components used throughout the auto industry. The ECE firmware simply does not activate that routine, there is an active/not active setting

3/ The stumbling occurs on both ECE and US versions of the earlier firmware and very little/none on the final version

4/ Where the purge valve is removed/deactivated on the US machines the firmware should be changed over to ECE, both versions are in the BMS-E, it is basically a coding process to swap from one to the other

The purge valve would have to be operating in more than just closed loop or the tank would pressurize, particularly on the older models which run mostly in open loop

Mag00, I have the specs on all the SPAL fans and there can be very large variations in flow rate between what look like the same fans in that range, the fans on the Terra and the Sertao draw 4-5 amps which is a fair old load on the electrical system for what you will find very is little gain, I am impressed by the OEM fan on the Terra and Sertao, it really keeps the temp down to the 100c setting it kicks in at. I watched it drop the temp on a Terra well below the 100c it cuts in at doing some tests recently. You should find the Terra fan cut in point in the workshop manual, it is in the BM manuals for all their models and you could spend plenty of time looking in all the manuals and I would expect the answer is it is a standard temp table and cut in point.

On the TR650 ECU the only effective inputs are Crankshaft Posn (RPM), Throttle Posn, Air Temp and Coolant Temp.
I noted that with my Dyna-Boost disconnected and the Purge Valve in place but no Cannister connected the Engine Stalls and crappy running occurred frequently during the warm-up period but also occurred when the bike had reached its operating temperature and things were fairly constant.
Other owners I have talked to have the same issues - the stalls occur on a warm/hot engine with fairly constant Air and Coolant temps, ie when the ECU should not be making adjustments due to Temperature changes.

My simple LED experiment showed me that the Purge Valve on the TR650 is active from the moment the bike is fired up - regardless of temperatures.
It appeared to operate in pulses when the throttle was opened and the engine was accelerating.
When the Stalls and crappy running occurred the Purge Valve was activated ie open.
All I do know is that with it capped off completely it removes one more variable and the bike runs a whole lot better, then with the Dyna-Boost connected it runs very well.

FYI, the TR ECU also has an air pressure sensor built into the underside of it.

Correct ! - I forgot about that one ;-)

I am not so sure that Air Pressure variances come into my Stall/Stumble equation as I am doing my tests in a reasonably constant environment - but, knowing this ECU to be fairly fickle, they could well do.

FYI, the ECU also monitors battery voltage, since the injector turn-on time is voltage sensitive. If the battery voltage dropped out it could lead to a stall. Not sure that happens though.

And as you know it also monitors the O2 sensor almost all the time to fine tune fuel and to calculate the long and short term trims.

GS911

My bike has a day/night sensor Also a speed sensor, (Strada has abs).

Well I have to say the injector and plugs have made a world of difference. They bike is running very well,44 degrees this Sunday morning and she fired right up and ran great. At long last I think I am done.

I doubt it very much considering that the cannister is open to atmosphere also and the vapours are collected by the charcoal inside prior to being sucked into the engine. See the diagram on the back of the right fork at the top, it has a warm air inlet.

Those of us with no access to any form of hardware/software to perform Firmware ops cannot do much about changing anything upon deactivation of the purge valve.

All I know is that with the Purge Valve out of the equation it is one less variable to consider.

I am sure the Terra owners in ROTW are like the BM 650 owners, very pleased we dont have the added complication of the vent valve arrangement