TB opens more than 100%
Thread Starter
Instructor
Joined: Sep 2016
Posts: 207
Likes: 34
TB opens more than 100%
I just finished porting my TB and when installing the blade again, I discovered that the blades open more than 100% (starts to close again).
Is it adjustable what the maximum movement of the blade is?
I would like to limit the movement, so that the blade is just horizontal.
Thanks guys.
Regards
Götz
Is it adjustable what the maximum movement of the blade is?
I would like to limit the movement, so that the blade is just horizontal.
Thanks guys.
Regards
Götz
Drifting
Joined: Jan 2005
Posts: 1,827
Likes: 301
From: Tucson Arizona
St. Jude Donor '08
Porting the TB is more of a science than you might think. See below from professional.
https://www.corvetteforum.com/forums...stalled-3.html
https://www.corvetteforum.com/forums...stalled-3.html
Thread Starter
Instructor
Joined: Sep 2016
Posts: 207
Likes: 34
Porting the TB is more of a science than you might think. See below from professional.
https://www.corvetteforum.com/forums...stalled-3.html
https://www.corvetteforum.com/forums...stalled-3.html
Or with other words, if there are problems with the self ported TB, I have an original on top.
However, the porting doesn't explain why the blade opens more than 100%.
Race Director
Joined: May 2004
Posts: 16,667
Likes: 1,209
From: Raleigh, NC
St. Jude Donor '15
Are you just moving it by hand or looking at it while it's running?
If by hand then there's your answer. Just because it will move that far doesn't mean the computer will or can move it that far in normal use
If by hand then there's your answer. Just because it will move that far doesn't mean the computer will or can move it that far in normal use
Thread Starter
Instructor
Joined: Sep 2016
Posts: 207
Likes: 34
Safety Car
Joined: Aug 2012
Posts: 3,960
Likes: 1,106
I wouldn't install a stop. Often there is a built in test/calibration routine for these motors and if you stop it prior to the intended end of rotation it may recalibrate so that full throttle is no longer fully open. I believe you are overthinking this issue.
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Thread Starter
Instructor
Joined: Sep 2016
Posts: 207
Likes: 34
It is also possible that it opens beyond 100% without a stop.
Given the cutting corners mentallity of GM I wouldn't be surprised.
I will give it some more thoughts how to find out, maybe someone has an idea.
Thread Starter
Instructor
Joined: Sep 2016
Posts: 207
Likes: 34
I just had a look at the mechanics behind the plastic cover and there are even two positive stops already.
One for fully open position and one for the fully closed position.
It just seems that fully open is a bit more than fully open in my case.
One for fully open position and one for the fully closed position.
It just seems that fully open is a bit more than fully open in my case.
Last edited by goec2468; Apr 8, 2017 at 11:56 AM.
Drifting
Joined: Jan 2005
Posts: 1,827
Likes: 301
From: Tucson Arizona
St. Jude Donor '08
As mentioned earlier, there are several tuning softwares that will tell you the exact position of the throttle blade while the engine is running. Find a friend with HP Tuners or EFI Live, and there are others.
Thread Starter
Instructor
Joined: Sep 2016
Posts: 207
Likes: 34
Here in Germany it is completely unkommen to have devices like HP Tuners and I don't know anybody who has it.
There is also not much knowledge around here, Chevrolet sells 500 Corvettes per year in all of Europe, maybe 150 in Germany.
Anyhow, today I installed my self-ported TB and the good news is:
No codes, no ill effect, all runs like it should
The even better news are, that two things that I didn't like, are cured:
1. When you wanted to drive really slow, like walking speed, you felt like riding a kangaroo.
2. Starting really slow from standstill with little throttle was not possible, the engine would just stop.
Both unpleasant bevaviours are gone and also I noticed that it idles much more stable, the rpm meter looks like nailed down now and the throttle response is much better. No hesitation, no stumble.
If it added any torque or not I don't know, but I would assume a little at maximum.
All in all it delivered what I wanted.
There is also not much knowledge around here, Chevrolet sells 500 Corvettes per year in all of Europe, maybe 150 in Germany.
Anyhow, today I installed my self-ported TB and the good news is:
No codes, no ill effect, all runs like it should
The even better news are, that two things that I didn't like, are cured:
1. When you wanted to drive really slow, like walking speed, you felt like riding a kangaroo.
2. Starting really slow from standstill with little throttle was not possible, the engine would just stop.
Both unpleasant bevaviours are gone and also I noticed that it idles much more stable, the rpm meter looks like nailed down now and the throttle response is much better. No hesitation, no stumble.
If it added any torque or not I don't know, but I would assume a little at maximum.
All in all it delivered what I wanted.
Last edited by goec2468; Apr 7, 2017 at 07:02 PM.
Melting Slicks
Joined: Nov 2012
Posts: 3,164
Likes: 686
From: SUFFIELD CONNECTICUT
I just finished porting my TB and when installing the blade again, I discovered that the blades open more than 100% (starts to close again).
Is it adjustable what the maximum movement of the blade is?
I would like to limit the movement, so that the blade is just horizontal.
Thanks guys.
Regards
Götz
Is it adjustable what the maximum movement of the blade is?
I would like to limit the movement, so that the blade is just horizontal.
Thanks guys.
Regards
Götz
Thread Starter
Instructor
Joined: Sep 2016
Posts: 207
Likes: 34
It is correct, that the electric motor and the position sensor determine how far to open the blade.
When you disconnect the battery and the later connect it again, the system doesn't know where the blade actually is.
It then calibrates itself by fully opening (up to the positive stop) and by fully closing it (to the other positive stop).
These positions then are used as 100% and 0% positions, that are used by the computer to determine hor far to open the blade.
If the assumed 100% position is a 110% in reality, then at WOT (when the computer sets the blade at the 100% position) the blade is beyond fully open - reducing max performance.
That is why I think about how to
- Measure where the blades move to in reality at WOT (not what the comouter things where they are)
- How to best make sure that WOT is 100% open - not more and not less
Regards
Götz
When you disconnect the battery and the later connect it again, the system doesn't know where the blade actually is.
It then calibrates itself by fully opening (up to the positive stop) and by fully closing it (to the other positive stop).
These positions then are used as 100% and 0% positions, that are used by the computer to determine hor far to open the blade.
If the assumed 100% position is a 110% in reality, then at WOT (when the computer sets the blade at the 100% position) the blade is beyond fully open - reducing max performance.
That is why I think about how to
- Measure where the blades move to in reality at WOT (not what the comouter things where they are)
- How to best make sure that WOT is 100% open - not more and not less
Regards
Götz
Melting Slicks
Joined: Nov 2012
Posts: 3,164
Likes: 686
From: SUFFIELD CONNECTICUT
It is correct, that the electric motor and the position sensor determine how far to open the blade.
When you disconnect the battery and the later connect it again, the system doesn't know where the blade actually is.
It then calibrates itself by fully opening (up to the positive stop) and by fully closing it (to the other positive stop).
These positions then are used as 100% and 0% positions, that are used by the computer to determine hor far to open the blade.
If the assumed 100% position is a 110% in reality, then at WOT (when the computer sets the blade at the 100% position) the blade is beyond fully open - reducing max performance.
That is why I think about how to
- Measure where the blades move to in reality at WOT (not what the comouter things where they are)
- How to best make sure that WOT is 100% open - not more and not less
Regards
Götz
When you disconnect the battery and the later connect it again, the system doesn't know where the blade actually is.
It then calibrates itself by fully opening (up to the positive stop) and by fully closing it (to the other positive stop).
These positions then are used as 100% and 0% positions, that are used by the computer to determine hor far to open the blade.
If the assumed 100% position is a 110% in reality, then at WOT (when the computer sets the blade at the 100% position) the blade is beyond fully open - reducing max performance.
That is why I think about how to
- Measure where the blades move to in reality at WOT (not what the comouter things where they are)
- How to best make sure that WOT is 100% open - not more and not less
Regards
Götz
Safety Car
Joined: Aug 2012
Posts: 3,960
Likes: 1,106
I am confident that the open stop is beyond the 100% open point by design. The number of degrees between stops is a known value greater than 90 degrees and the calibration protocol steps the positioner through the entire possible range of motion and then calibrates it based upon the designed in overshoot so that commanded fully open is truly fully open. Although accurate operation of these sensor controlled stepper motors is very good it is not possible to avoid some inaccuracy to a fraction of a degree and if the positive open stop was EXACTLY at fully open then you could easily end up with the situation where commanded fully open hits the stop before the sensor agrees it is fully open and you would have an error situation where the stepper motor would be attempting to open past the stop. By designing a few degrees of slack into the system and calibrating based upon this known amount of over-travel you avoid this error situation and will have a throttle blade which is fully open in terms of air flow and resulting performance even if it is actually half a degree plus or minus from true full open.
Melting Slicks
Joined: Nov 2012
Posts: 3,164
Likes: 686
From: SUFFIELD CONNECTICUT
I am confident that the open stop is beyond the 100% open point by design. The number of degrees between stops is a known value greater than 90 degrees and the calibration protocol steps the positioner through the entire possible range of motion and then calibrates it based upon the designed in overshoot so that commanded fully open is truly fully open. Although accurate operation of these sensor controlled stepper motors is very good it is not possible to avoid some inaccuracy to a fraction of a degree and if the positive open stop was EXACTLY at fully open then you could easily end up with the situation where commanded fully open hits the stop before the sensor agrees it is fully open and you would have an error situation where the stepper motor would be attempting to open past the stop. By designing a few degrees of slack into the system and calibrating based upon this known amount of over-travel you avoid this error situation and will have a throttle blade which is fully open in terms of air flow and resulting performance even if it is actually half a degree plus or minus from true full open.
And we have to accept a + or - small possible error factor which wouldn't amount enough to be concerned about. I quess one could manually do a perfect 90 degree WOT measurement and tweak the WOT stop to just beyond that for wiggle room and depending how much further that WOT stop is set from the TB vender.
Race Director
Joined: May 2004
Posts: 16,667
Likes: 1,209
From: Raleigh, NC
St. Jude Donor '15
It is correct, that the electric motor and the position sensor determine how far to open the blade.
When you disconnect the battery and the later connect it again, the system doesn't know where the blade actually is.
It then calibrates itself by fully opening (up to the positive stop) and by fully closing it (to the other positive stop).
These positions then are used as 100% and 0% positions, that are used by the computer to determine hor far to open the blade.
If the assumed 100% position is a 110% in reality, then at WOT (when the computer sets the blade at the 100% position) the blade is beyond fully open - reducing max performance.
That is why I think about how to
- Measure where the blades move to in reality at WOT (not what the comouter things where they are)
- How to best make sure that WOT is 100% open - not more and not less
Regards
Götz
When you disconnect the battery and the later connect it again, the system doesn't know where the blade actually is.
It then calibrates itself by fully opening (up to the positive stop) and by fully closing it (to the other positive stop).
These positions then are used as 100% and 0% positions, that are used by the computer to determine hor far to open the blade.
If the assumed 100% position is a 110% in reality, then at WOT (when the computer sets the blade at the 100% position) the blade is beyond fully open - reducing max performance.
That is why I think about how to
- Measure where the blades move to in reality at WOT (not what the comouter things where they are)
- How to best make sure that WOT is 100% open - not more and not less
Regards
Götz