TPS adjust/TB balance/air bleed screws

[raz]

Why is the 150mv setting at key-on bike-off so important? It seems to me the setting (whatever it is) at running idle would be a lot more important as it represents actual running conditions. Anyway, I couldn't get 150mv after following all the instructions, but I found the bike runs great at 527mv running idle (1150 rpm).

It is very important because the TPS is the ECU's only way to know how much the throttle is open. If the 150 mV is set correctly, the ECU can calculate the "degrees open" from the TPS reading. If it's not set correctly, the ECU will have the wrong picture, not just at idle but at all throttles including WOT. To some extent you can do this on purpose to have a leaner or richer mixture but you should be aware that it may have effects on ignition advance too.

 

This is a design choice. The alternative is either to have a software setting telling the ECU what TPS voltage corresponds to idle (or some other known point) or the ECU could sample it at power on. The latter has an important drawback: if you turn the ignition on with some throttle applied (like the fast idle lever), this will be considered the idle reading. That will likely produce a too lean mixture until you turn the ignition off and on again without fast idle. Of course, the software could also be clever enough to re-set the base voltage if it ever goes lower than was sampled at startup.

 

As far as I know, 16M and 15M is hard-coded for the 150mV base. As a side note, Cliff's MyECU is the other variant, it has a software setting for TPS reading at idle. And if it's set to zero, it will sample at every start.

[waspp]

Ok, so i had just adjusted my valves before reading this topic so i figured i would try Micha's 6 step tps adjustment procedure. First off its way easier, second it works great! Before I set the tps at 1150 rpm i checked the current value which was 550mv, so i set it back to around 532mv and went for a ride. I noticed right off that the pinging was nearly gone and the bike seemed to run great. Again as some have said it may not work for everyone and i would like to be more accurate with rpms and such but i have to say the bike runs pretty good!

 

Hal

[dlaing]

Ok, so i had just adjusted my valves before reading this topic so i figured i would try Micha's 6 step tps adjustment procedure. First off its way easier, second it works great! Before I set the tps at 1150 rpm i checked the current value which was 550mv, so i set it back to around 532mv and went for a ride. I noticed right off that the pinging was nearly gone and the bike seemed to run great. Again as some have said it may not work for everyone and i would like to be more accurate with rpms and such but i have to say the bike runs pretty good!

 

Hal

How strange.

The theory has been that a difference of 532 vs. 550mV would not be perceptible as it only moves through a very small portion of a fuel cell.

And for it to ping at 550mV but not 532mV is also counter intuitive.

I am ready to give up and buy a bike with carbs

[Tom M]

Hay Tom,good stuff.we just need to no what your everything backed off TPS is now.there is a bike in town with similar probs.

 

I checked my plugs and they look good. The bike runs good too. I pulled the throttle link, verified the high idle cam wasn't touching, and checked my baseline TPS reading. Drum roll please...

 

 

 

 

 

 

 

 

 

 

 

 

250mV

 

A full 100 mV over the factory spec! I don't care what the manual says, this flat out works on my bike. Thank you to everyone who contributed to this thread, to Dave & Ryland who took the time to put the instructions together, because without them I likely never would have got into this, and especially to Micha for coming up with this shortcut. I owe you all a beer

[dlaing]

250mV

Wow.

Thanks for taking the time to get that reading.

Following the description of your process, that is as we predicted, but it boggles the mind that the tolerances could be that far off.

I was kind of hoping there was an error in your process or your readings, but that confirms that all your readings were true.

What still impresses me is that despite your fully closed being 100mV higher than mine, your WOT voltage is actually lower than mine!!!!

I'd like to further explore the use of WOT to set the TPS voltage to 4.86V or whatever is deemed most ideal.

[waspp]

How strange.

The theory has been that a difference of 532 vs. 550mV would not be perceptible as it only moves through a very small portion of a fuel cell.

And for it to ping at 550mV but not 532mV is also counter intuitive.

I am ready to give up and buy a bike with carbs

 

I wouldn't make the assumption that the mv change was the complete fix but rather all of the steps that Micha follows. My bleed screws were in about 1/2 a turn and my TB were slightly out of sync. The 550mv was just for me to see where it was before. I have too admit the pinging going by by was a pleasant surprise. I actually had a difficult time getting it to ping, lugging it way down and grabbing a fistfull of throttle in high gear. All i can say is it runs fine.

[dlaing]

I wouldn't make the assumption that the mv change was the complete fix but rather all of the steps that Micha follows. My bleed screws were in about 1/2 a turn and my TB were slightly out of sync. The 550mv was just for me to see where it was before. I have too admit the pinging going by by was a pleasant surprise. I actually had a difficult time getting it to ping, lugging it way down and grabbing a fistfull of throttle in high gear. All i can say is it runs fine.

Thanks for the added details. Again going from half a turn to a full turn of bypass should make it run leaner and be more prone to pinging.

I guess it was the syncing that have cleaned up the pinging.

If the valve adjustment was made after the pinging, that could have helped too.

[mark.gilmore]

Gosh,I love this sh#*t.I will be trying this on Morris Sod's bike ASAP.

[al_roethlisberger]

For all this talk of modified TPS settings, are all the other recommended process and settings(such as bleed screws) still the same as we've recommended in the "how to" posts?

 

I ordered the VDSTS so I can check/adjust the trim and TPS voltage, so that should help simplify things.

 

 

Al

[waspp]

Thanks for the added details. Again going from half a turn to a full turn of bypass should make it run leaner and be more prone to pinging.

I guess it was the syncing that have cleaned up the pinging.

If the valve adjustment was made after the pinging, that could have helped too.

 

The valve adjustment was done before about a week ago and the pinging persisted. At that point I figured it was time to check the tps and try to find anything out of adjustment.To be honest the sync wasn't horribly bad and I just went through the steps as posted here. Maybe the pinging was as simple as old gas from over the winter, thats a possibility as well. I'm surprised to see Toms baseline reading thats way out there but hey if it runs well who are we to argue! If I get ambitious I'll check mine as well. Al has the right idea the software should provide a more accurate way to set things up.I've been close to pulling the trigger for that as well.

 

Hal

[raz]

Again going from half a turn to a full turn of bypass should make it run leaner and be more prone to pinging.

Think beyond idle, Dave! Increasing bypass will have the effect that you must close the throttle plates accordingly in order to get desired idle speed. Using Micha's method, this will end up as a richer mixture at all speeds except idle.

[dlaing]

Think beyond idle, Dave! Increasing bypass will have the effect that you must close the throttle plates accordingly in order to get desired idle speed. Using Micha's method, this will end up as a richer mixture at all speeds except idle.

You are correct, if you add mV at the TPS.

Wassp went from 550mV to 532mV and 1/2 airbypass to 1 full turn air bypass.

The added bypass should require less throttle to maintain the proper idle, which could explain the drop from 550 to 532mV, or he could have dropped the throttle valves even more and added more mV, which would make it run richer, as you suggest.

We just don't have enough information.

 

I'd like to modify the instructions, and make them more complex to include a path for people to follow if they have one of these bikes. Unfortunately, like the Micha method, it may be a bit of hit or miss approach, but with instructions on how to re-aim and try again.

For example, Tom M followed the pinned "how to" steps and ended up at 480mV at idle with air bypass screws closed, WOT 4.78V, and it running poorly. Doing it the Micha method on his bike required 100mV more at the fully closed baseline, and ~40mV more at WOT. They are presumably not both 100mV difference, because of inaccuracy at WOT in the Volt range, but mostly because the TPS is not completely linear. (see Jeff's chart to see how linear it is. The slopes look correct for the variation)

It might make sense to go through the outlined steps, but limit the air bypass range to between one half and one full turn out, and to limit the mV range as adjusted using the left idle screw to 3.4-3.6 degrees (511mV-532mV). In order to keep the 1150rpm idle, the TPS might need adjusting, changing the 150mV baseline.

I still wonder if 4.86V at WOT could be used as a the baseline. The problem is that it is not so accurate, and we still need to disconnect linkage, but I'll bet it would have worked for Tom, although it would be too rich and maybe 4.82V is fine????

It is interesting that MPH's website says,

Anything below 4 degrees open ECU considers bike to be at idle (as seen by 'flag' on diagnostic program)
Anything above 80.5 degrees open ECU considers bike to be at WOT (as seen by 'flag' on diagnostic program)

4 degrees is about 574mV and 80.5 degrees is about 4.75V.

What the idle and WOT flags do is anybody's guess, but no doubt we don't want to tune out of that range. Also we don't want to exceed 5.00V at WOT. The mid point between the 4750mV flag and the maximum capability of the TPS is 4875mV

According to my Tuneboy maps there is no 100% throttle row of cells, but an 84.56 degrees (a little above 4.86V)row of cells and the row below that is 60.73 degrees (about 4.2V).

Another question is, which is more valuable, WOT with TBs connected, or disconnected???

I know I would want atleast 4.75V at WOT connected.

WOT may also be a good way to balance the TBs....

[raz]

You are correct, if you add mV at the TPS.

Wassp went from 550mV to 532mV and 1/2 airbypass to 1 full turn air bypass.

The added bypass should require less throttle to maintain the proper idle, which could explain the drop from 550 to 532mV, or he could have dropped the throttle valves even more and added more mV, which would make it run richer, as you suggest.

We just don't have enough information.

Your right, we read his description in different ways.

 

I still wonder if 4.86V at WOT could be used as a the baseline. The problem is that it is not so accurate, and we still need to disconnect linkage

If you still need to disconnect linkage, what is the benefit of measuring at WOT? We've discussed it before but I can't remember. I'm pretty sure you can give or take one degree at WOT with no mixture problems, but not so at idle so I really think you should calibrate it at the lower end.

 

It would be interesting to know peoples WOT readings though.

 

WOT may also be a good way to balance the TBs....

Not sure what you meant there but maybe it was this: this winter I "pre synched" the TB's by adjusting the white knob so both TB's hit the WOT stop at the exact same time. Yesterday when I checked with vacuum gauges, it was spot on at 4000 rpm (and other rpms I tried). So at least on my bike, you can synch with a feeler gauge instead of vacuum gauges. I'll probably use vacuum gauges anyway when available, but this is good to know in a pinch!

[Ryland3210]

Micha's method compared to the How To method:

Step one - Set your valves to world settings

Step two - Set your bleed screws to open 1 full turn

Step three - Synch throttle bodies at just off idle (around 1800 rpm)

Step four - Set idle to 1100 using left idle screw adjuster only

Step five - Set TPS to 3.6 degrees (I forget what that translates to in mv..someone here will know)

Step six - Ensure idle trim is set to zero

 

One important difference is that the How To method leaves nothing to chance, whereas the Micha's method takes shortcuts by making assumptions.

 

For example, it assumes the left idle screw controls both throttles and that the right idle screw and fast idle is not in contact.

Synchronizing the throttle bodies at just off idle should eliminate interference from the two idle screws so that the connecting rod is in control, just as in the How To method, except that any variation in the flow rate delivered by the two bleed screws will require an offset of the two butterflies in order to compensate. The assumption here is that the difference is negligible. The How To method avoids this interaction.

The How To method quotes 521 mv as the middle of the published ranges as a guideline. That corresponds to 3.5 degrees, almost identical to Micha's 3.6.

 

The other important difference is that Micha's method apparently disregards the 150 mv at throttle closed baseline calibration in favor of forcing the TPS to be adjusted to 3.6 degrees (532mv) at 1 full turn of bypass opening and 1100 RPM. In the case of the How To method, the TPS is calibrated at throttle closed, and if air bypasses are not opened at least 1/2 turn to achieve 1100 to 1200 RPM, then the idle screw is loosened by closing the throttles in steps (which will reduce TPS voltage) until they are.

 

Let's try an example using Micha's method. Suppose the TPS is calibrated correctly, 150mv at throttle closed.

Air bypasses are opened 1 full turn and left there. At 1100 RPM, it so happens that the TPS indicates 3.0 degrees. Micha says adjust the TPS to read 3.6 degrees anyway. The result is a richer mixture throughout the throttle range.

 

In my opinion, so long as the assumptions the Micha procedure makes are reliable, it has merit provided one is willing to accept the fact that it will likely result in an uncalibrated relationship between TPS voltage and actual throttle opening. For some riders and bikes this may be entirely satisfactory. However, it is important to understand that maps provided by others which one may wish to use as is, rely upon a TPS calibrated to the throttle closed baseline. The How To method should be used when setting up the bike for dyno tuning or using a map provided for a particular set of modifications or special purposes as is.

 

A lot of this has been gone over in previous posts. I just thought I would summarize it from my point of view.

 

regards, John

[dlaing]

Your right, we read his description in different ways.

Yep and my comment on it could be taken many ways. I should have been clearer

 

If you still need to disconnect linkage, what is the benefit of measuring at WOT? We've discussed it before but I can't remember. I'm pretty sure you can give or take one degree at WOT with no mixture problems, but not so at idle so I really think you should calibrate it at the lower end.

Now that we are finding some bikes with variations in the base 150mV position relative seemingly to both WOT and idle, the WOT reading may have more value for setting than the baseline. Since it is the flip side of the 150mV position, it theoretically is just as valuable as the 150mV baseline, and if the WOT position does not have the variations between bikes that the fully closed 150mV appears to have, it could prove to be MORE valuable. The problem is the inaccuracy of the voltmeter when trying to differentiate 4.860V from 4.850V, meanwhile differentiating 150mV from 160mV or even 151mV is not a problem.

So, the value of reading at WOT is to eliminate the problem that Tom experienced...we just have a technical inaccuracy issue.

Disconnecting the linkage is not a big deal. Perhaps disconnecting it is not even necessary once TBs are balanced, and disconnecting won't be necessary if the method you outlined below works:

Not sure what you meant there but maybe it was this: this winter I "pre synched" the TB's by adjusting the white knob so both TB's hit the WOT stop at the exact same time. Yesterday when I checked with vacuum gauges, it was spot on at 4000 rpm (and other rpms I tried). So at least on my bike, you can synch with a feeler gauge instead of vacuum gauges. I'll probably use vacuum gauges anyway when available, but this is good to know in a pinch!

That is almost what I meant.

I was thinking we could screw in the adjuster a few turns so that the right side will top out at WOT first, measure TPS voltage at WOT, with WOT activated not from the throttle but by moving the linkage, set to 4.86V(or whatever is deemed ideal), and then turn the adjuster screw out until the TPS voltage reading at WOT starts to drop and then return it in to the exact point where the Voltage returns.

I am not sure if that is clear or all correct. I need to actually try it first...

Maybe at the next rally I can sneak around at night while everyone is drinking and sleeping and change everyone's WOT TPS settings to 4.86V. If the next day nobody kills me it could be considered a success.