Secondary throttle plate removal

Tried it.

I had a little time yesterday being Presidents Day and all so I thought I'd try the secondary restriction removal.

Don't forget to remove the hidden two fasteners that srew the throttle body plenum to the thottle bodies. Once I found those all was good. Not a whole lot of room to work for my big hands but I managed this mod in about 1 hour.

A cordless impact driver is the way to to go to loosen the plate screws. They are fairly small and very snug, you need a tip that fits well or you will strip the heads. Then you are hosed.

I did the tape everyhting off trick so the screws did not fall into the throttle bodies.

All is well. Stock 07 standard with cat by pass and no secondaries. Standard TOR tune. Runs well. I notice a much "snappier" response in all gears, espicially 2-4. Good mod for the time it took.

just fit a gipro atre.Easier than messing about taking secoundaries out.

step1 said:

just fit a gipro atre.Easier than messing about taking secoundaries out.

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Unless your fittin K&Ns of course.

TurboFan said:

The ECU reads a different map for idle, and tune boy DOES NOT set that map open to 100%. As soon as you hit the throttle (come off idle) the servo motor cranks them open to the map Tune Boy has set at 100%. But it doesn't do it as fast as you can twist your wrist.

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False.

There is no separate secondary TP position map for idle. The secondary map is indexed by RPM and gear position. For any of gears 1-5, you can set the secondaries to any position you like, and as long as you're in one of gears 1-5, your secondaries will obey.

Now there is a separate secondary map for the neutral gear position, but TB doesn't let you see or fiddle with it. Maybe that's what TurboFan is mistaking for the idle map he writes of in the quote.

It's easy to confirm this. Plug TB into your bike and crank it up. Launch TuneBoy (not TuneEdit). Go to the sensor page. See all the numbers. Find the one that's labeled "2nd Throttle %". Put the sidestand up and put it in 1st gear. Watch the number immediately change to whatever you have your TuneEdit "Sec" map set at for 1st gear and 800 RPM. Rev the engine. See the number match whatever you have set for the different RPMs in the bottom row in your "Sec" map. Now put the bike in neutral. See that the number changes to a value that you have no control over.

idk said:

I suspect that in the first three gears it would run a little lean at the places where Triumph set the secondaries to not open fully. This is because the computer is expecting less air so supplies less fuel. However, I am happy to be wrong because the computer also measures the vacuum (or air pressure) and maps the fuel to that as well as the throttle position, so that may be enough to compensate.

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True and false.

If you command the secondaries open any more than they are programmed to be in the stock map, your bike will be inhaling more air than the "F" tables tell the bike it's inhaling, and it will therefore run lean. How much more air is the question, and the consensus around here seems to be that it's not enough to be concerned about. I have seen no data to say whether the consensus is true or not, but it doesn't seem terribly unreasonable. So the first part of what you wrote is true.

You're also correct that the ECU maps fuel to manifold absolute pressure, but that map is also based on an air-volume expectation--i.e., the L tables. For instance, if the MAP is 486 millibars and the RPM is 2000, the L1 table tells the ECU to expect, say 2000 units (whatever the TuneEdit units may be) of air in cylinder 1. Now if you open up the secondaries, the bike will actually inhale more than 2000 units of air, but the ECU is still expecting that 2000 units. So it'll add the proper amount of fuel for 2000 units of air, but it'll really have, say, 2100 units of air, and will therefore be lean.

So the bottom line, I guess, is that you're wrong when you say the bike automatically compensates for whatever increase in air results from commanding the secondaries to be more open than the stock map.

idk said:

Thanks, I figured that it would be something like that. However, I'm still not sure why both maps are needed. Why isn't the throttle position map alone sufficient?

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I think that's a great question. It'd make tuning so much simpler if those pesky L tables weren't complicating things.

But given that they're there, it'd be nice just to know the logic that the ECU uses to determine which set of maps to use. The conventional wisdom around here is that L tables are used below 6% throttle, and the F tables above 6%, but I'm almost certain it's more complicated than that.

Another helpful project that one of us with under-utilized electrical engineering experience/knowledge might tackle is to figure out a way to force the ECU to always use the F tables--but he'd first need to know the logic if he were to have any hope of success.

idk, EXCELLENT post. When I have the time to study it in more detail I am sure I will be back with questions, or at least with a note to confirm that I "got it now". But on the issue of don't bother or use the resistor etc. I would stess one point. Anything electronic, (the resistor, GIPRO, or Tuneboy) sets the throttle plates to 100%, BUT NOT AT IDLE. They close at the very bottom of the rpm range. I think that is good, and would put mine back in, (if I hadn't busted a screw the last time! ) If you are really in a hurry, (racing) bring the engine off idle when you stage and the plates will open in time to be out of the way.
But if it is you and your buddy, using a "Butt Dyno" the one with the plates removed will seem way faster, when it is idling in first gear and you snap open the throttle. In a race I doubt you will measure the difference, but it will definitely snap off the line a tiny bit more violently.
And finally IMHO removing the plate will make the bike very slightly more prone to STALL if you give it a wrist full and then snap the throttle shut. That's my OPINION and I am not sure I can justify that with any facts, but it seems like it happens.
Now I gotta go read the Tune boy manual and see if I can get the tables straight with a little help from idk!

Excuse my obvious ignorance, but is there a difference between the secondary throttle plate removal and the secondary throttle position sensor removal? It sounds like their removal accomplishes the same thing... :?

Phil I am not sure what you are referring to about removing the secondary Throttle Position Sensor (TPS) which I am not aware of anyone physically removing.
There are several schemes, (Tune boy, GIPRO the resistor mod) all trying to address the problem of the 7% (or maybe 10% or 15% depending on who you talk to) reduction in power in first gear.
The reduction in power is a result of the combined effects of the fuel map, the degree of ignition advance and the percent that the secondary throttle plates are not opening.
Removing them completely only address part of the problem, but it does so in a way, when combined with Tune boy etc, that is more obvious to your 'butt' dyno. Still, I don't recommend it, as I BELIEVE, (this is my opinion) that the plates removed makes the engine a VERY small amount more likely to stall in some conditions. I don't BELIEVE it makes it significantly faster, (but your BUTT dyno will like it).
And always remember, ... I have been wrong before.
I have the predator exhaust, Triple K&N's, Tune Boy and I have the secondary plates removed. All of them that is except the small piece of the one screw I broke off!

i thought that when people refer to elimination of the secondaries they refer to the removal of the secondary TPS?