Why does my FI bike have a choke plate? TE449/511

So, how about it?


Why do I have a second throttle plate that is basically an electronic choke plate in my TE511 throttle body?

Why would you choke a FI engine when starting?




Also when does this thing move? What tells it to close/open? Temp sensor? Run time? When does it close again?

Someone help me out here. It would be much much more effective to just inject more fuel at cold start. Why would you reduce airflow?

Is the throttle body too large (46mm?!) and it need more vaccum on startup to pull or draw the air fuel charge in?

That makes no sense!


Wheres an engineer when you need one?

If i remember correct. TE/TXC use a throttle body with 2 throttle plate, and TC bike use a throttle body with only 1 throttle plate. It has something to do with TE/TXC would get smoother power curve.

Right on that above. My TC 449 engine had a single butterfly. I'm running it with the stock BMW double flap FI Unit, just like the above picture though and it runs great. Not something to mess with. They got it pretty well dialed.

But but....I really think this is cause for my interesting "issue"

When geared up, if you whack the throttle open, you can feel it slowly build power. It is missing the "snap" of a carb bike.


I figure its a 46mm throttle body (overkill for a 470cc engine) so they use the secondary flap to increase the air velocity by opening it slower? Or something? To prevent a "bog"?

So this is an old post, & you've probably worked it out, but the second butterfly is a 'fly-by-wire' type electric throttle controlled by mapping from the ecu.


It only opens a little at idle as the cam on the other end of the shaft lifts an arm for the primary (cable operated) throttle, in an attempt to control idle speed.

Unfortunately, on my TE449 at least, the idle control is so erratic it is of no help what soever.

Almost all petrol cars now have a fly-by-wire throttle, it is so the manufacturer can control how much throttle opening there is for a given situation

& provide an environmentally friendly amount of fuel.

You can have your foot on the floor 'asking' for 100% power & the ecu may give you 85% & ramp up slowly from there to 100% to reduce emissions.

I assume this is what Husky/BMW/Keihin were trying to do with this system, but failed......miserably!

Read all of the posts about TE449/511 bikes stalling/flameouts/low idling/high idling.

Not enough time spent sorting it out at the factory before releasing it!!

I've set my bike up as a TC runs by removing some bits, but the system still thinks it has control. It runs well now.

Removing the secondary butterfly isn't something new, others have done it since the release of this engine and I have mentioned it in several of my threads.

My 511 runs perfectly with the dual butterflies. I find your criticisms invalid due to the stalling issues being map related. And yes, a stock TC449 does and will flame out as well. The TE throttle body does work and works well. It allows the engine to start with an automatic choke in all weather conditions and it provides a much smoother power curve, even on highly modified racing engines such as my own. Proper tuning of the fuel and ignition curve is the real solution to your flame outs.

Tinken,

I appreciate your view as someone who has done a lot of work racing these bikes & I am not replying to get a rise out of you, please don't take

it that way.

As I said in my posts elsewhere, not all bikes are having trouble.

MY bike does not & will not control idle after 18 months of dealers & my self trying. I am glad yours & lots of others do.

The last thing I wanted to do was remove factory stuff from my bike. I would have loved it to idle up & not hang.

I tried removing the idle arm as a last resort test, knowing I could return it to standard, expecting it to make it worse. It didn't.

Now with just the brass screw to idle the bike & the tps moved to a 'happy spot' at idle, it doesn't stall or run-on for the first time since owning

the bike.

It did not matter weather the dealer (via the hand reader), or myself (as detailed in the posts) reset the tps, brass idle screw or checked

correct manifold vaccum readings, it was not able to ALWAYS idle correctly.

Yes, I have ended up with a poor-cousin solution, but now it always idles when asked.

We all know the factory mapping is flawed, but the things I did to my bike helped me to get it run the best it's ever been, to the point where I

don't ride trying to second guess what it will do next. (No it isn't as clean & sexy as remapping with a piggyback, but much, much better than factory)

I haven't seen any posts in regard to the second butterfly being removed, but this is the thing that has woken my bike up the most.

Leaving the shaft & electronics there has meant I have no downside after this mod.

The second flap serves no useful purpose, it is only there for emissions, otherwise the TC would have it.

BMW marketed it as 'smooth power', but why smooth an engine that only had 46.5hp, that was only class average in 2011 when released.

The TC had 50hp & needed no 'smoothing' of it's power. (Interesting that BMW chose not to list 1/2 the enduro competition's figures too.)

http://motosports.lv/E84E3207-5E92-...2FA93A8ED/site/i/449_511_analize_apraksti.pdf

As I said, I am not trying to disregard your experience with these bikes, just listing things that worked for me.

Please, if you get a chance on a near stock bike, try it out for yourself, you may be surprised by the results, I certainly was.

No, I understand that. And I am happy that owners like yourself are looking for new ways to improve these bikes. What I am trying to keep from happening is everyone jumping the bandwagon and playing with their efi units. I have seen what happens when you get something set a little bit off. There are many things that can go wrong on the efi system, a sensor, a setting, faulty eprom flashing, a shorting wire, etc. Just taking the unit off of the bike can disable it from working, we know because we have done it and we're experts on the units.

Thanks for the response.

If you do take off the throttle body, make sure the power is shut off. Cycling the efi system when not installed causes strange fluttering on the butterfly and then damage.

Also on the hp thing, most bikes are rated in hp at the crankshaft and not at the wheel. The TE511 is rated at 51hp at the crankshaft, but that calculates out to 42.5 hp at the wheel or brake horse power where we would measure it on a dyno. Figure around 19-20% as a general rule. So with 46.5bhp * 1.2 would be 55.8hp which sounds about right.

Yes, and a very valid point not to be overlooked.
If you aren't comfortable doing this kind of work on expensive components, please leave it alone or to someone who can.
Read the disclaimer at the start of the post also.

I know for a fact that the secondary throttle is causing some of my personal issues, and I will try removing it. I do not have a dead throttle or hanging idle issue. But I do have reduced engine braking because I had to raise the idle/bypass screw to prevent stalling when you first touch the throttle.

I had my throttle body open and I watched it. Witth the bypass screw in the stock position, when you touch the cable throttle, the secondary butterfly does not open and the bike coughs and dies.

So I take a bit out of the screw, which raises the engine rpm (and causes reduced engine braking because the idle is higher) and it idles at 2000rpm solid. If you open the cable throttle quickly it does not cough and die. If you do it 3 times in a row, it will cough and die. The whole time the butterfly is barely moving and is slow when it does. Everytime I touch the throttle and the TPS sees it moving it adds fuel, but the engine airflow hasn't changed as the throttle body plate is not following the cable throttle.


That said you could just pull fuel at the first openings to try to prevent that? I don't know. But the air bypass screw thing seems to make the largest difference in my first touch of the throttle stalling. But then the engine lags/hangs and doesn't come to a idle as quickly.

This is what gave me the idea with mine, watching the shafts working under the cable cover.
It would seem the system gets confused with a few quick blips on the throttle.....

Be really careful about this. You have an issue that is related not just to throttle position, but to rapid throttle opening. If you take fuel out at low throttle angles, the bike will be lean when you're at those low throttle positions in steady-state.

Part of the issue with diagnosing this problem is that we don't have knowledge of the extent of the fueling code in the ECM. If, as you state, it simply is adding fuel as a function of primary throttle position, while the secondary isn't opening, it absolutely will run rich and possibly die (like you suggest). However, the ECM could very well be compensating for the fact that the secondary isn't opening (assuming it has control/knowledge of the position of the secondary, which I believe it does, but I am not super familiar with that family of bikes).

In other words, just because the secondary isn't following the primary, doesn't necessarily mean that the fuel delivery will be wrong, if the ECM is aware of and compensating for this.

I am a proponent of EFI, but situations like this are one of the downsides to an EFI system. With a carb, you can't always figure out what it's doing, because it's mechanical. With fuel injection, so much of the system is hidden from view (buried in code) that you might think you're "fixing" a "problem", but you don't know.

The best way to investigate this is to log a couple of parameters (RPM, throttle position, injector pulsewidth, AFR) and see what the ECM is doing. That is not a trivial task, though.

I like the 449/511 family of bikes, and I like EFI, but I will say that my 610 (FCR) never idles wrong, stalls, or flames out. Of course, neither does my EFI Duc... Clearly Husky/BMW screwed up the engineering on this system.

I'm a big EFI fan to Kyle, it is the main reason I traded up from my carby fed WR450 to the TE.
I've had a fair amount of experience with aftermarket Haltech computers & EFI late model cars, I assumed that a modern efi bike would be no different.
My jetted '05 WR NEVER, EVER stalled or flamed out in 185hrs of riding.......sigh.
It wasn't as nice as the TE449 to ride though, or as fast.

Seeing all the usual sensors on the TE system I assumed the operation would be as for any other efi system.
TPS to monitor throttle inputs, a MAP sensor to monitor engine vaccum (load), RPM pulse from the crank sensor & temp sensors in the coolant & air box. _ All present & correct sir!

I'm not sure it uses the MAP sensor for load, certainly not at idle, where if you move the tps slightly (i'm talking a bee's whisker) either way, it changes fueling.
The way I see it, if it were running on the MAP sensor for load at idle, the TPS shouldn't really change the running unless it went away from the 'idle range ' of voltage.
As long as it stayed in the 'sweet spot', maybe 0.45 -0.6v, whatever & the throttle shaft didn't move, the MAP signal would be the same & the fueling shouldn't change.

Some aftermarket efi systems give you the ability to run an idle strategy based on a closed throttle signal from the TPS & then use the MAP sensor for load when off idle, maybe that's what Keihin/BMW have done in this case.
Usually the only time you would use this function is when you have massive cams in that don't provide a clean vaccum signal to the MAP sensor.
Maybe giving the ecu a 'clamped' MAP voltage for testing & moving the tps would prove one way or the other.... hmmmm, science lol.

All of this is pointless though, as the maps are locked up in code that no one has broken into yet.

Mods & Piggyback ECUs are the only course of action.....

The system does have a rpm/position sensor in the stator, not sure about the load sensor. Temp sensors in the airbox and coolant, yes. Air speed sensor in the tbi unit I believe, don't quote me from my memory haha.

No air speed(flow) sensor, only Manifold Absolute Pressure - MAP vaccum sensor, an Air Flow Meter would work better though as they react quicker to throttle changes than a cheaper MAP system....

I disagree about the air flow meter. While a MAF system is accurate, they are also expensive, cumbersome, and possibly restrictive. A speed-density system (MAP/TPS and RPM) is much simpler and easier to implement.

TPS works fine as a load metric, it's just not as nice as MAP because it's very nonlinear, so the map/curve shapes can be funky, and therefore require more tuning time on the back end.