Throttle Position Sensor

[Ryland3210]

I see. It would seem that the procedure has now ossified to become dogma. So be it.

 

Still, one wonders if any of the creators of this procedure have tuned a bike that has the Guzzi race ECU and pipes? If not, how can the procedure be proven or even tested for these machines? If so, maybe it works for some machines under the particular use that those owners put their machines to but wouldn't for others?

 

Here's a little story. We at our shop have had two '04s that owners themselves fitted with the Ti pipes and ECU. These folks followed their normal tuning procedures and never could get the bikes to run right. These stumbled and hesitated under certain conditions of part throttle and small throttle changes and weren't as smooth-running as before and one pinged badly. Both owners later sold their V11s on consignment or traded them in because they could never get them to run right. One of these folks was an auto mechanic. In both cases, with 10 minutes of tuning, our service manager had them completely sweet-running. One he told me was the best-running V11 he had ever ridden, and he has ridden hundreds of V11s. Also, he has personally owned three V11s that had the Ti pipes and one with other pipes. He insisted I take it for a ride, and it ran perfectly. I deliberately tried to make it misbehave but it didn't. It ran as good as mine with a PCIII and custom map, even though it had neither, just a proper tuning for Ti pipes.

 

You might at least consider that the Guzzi race ECU is different enough that it could benefit from altered tuning compared to that of the normal ECU.

 

Of course it's not dogma! It was not developed by a couple of true believers which expect others to accept it on faith. It included the input from numerous contributors, and that open process continued for a long time, until there was nothing more to add. Recently pictures of how to connect a voltmeter to the TPS were included, as an example of a contribution to improve the procedure.

 

The procedure is not intended to discredit or render obsolete, the professional, experienced tuners. It simply results in calibrating the TPS 150 mv baseline and balancing the throttle bodies, which are fundamental to any tuning method. It provides a idle TPS voltage based on sound information. The idle TPS setting is a variable which one may wish to vary from that to whichever of the numerous different recommendations from experts and manuals we found during the research. In fact, although I am not an expert tuner, I varied the idle TPS myself slightly towards the low side to meet my personal goals.

 

The study was undertaken precisely because the various expert tuners of these bikes each has their own rules of thumb, recommendations and experiences, and the various manuals are not consistent. An important goal was to determine how the system works, in order to come up with a reliable procedure. Time was taken to explain how the system physically works. Whenever a question was raised, it was accepted, analyzed, discussed, and resolved.

 

The purpose of the effort was to provide a procedure a layman could follow and achieve a solid, basic synchronizing, TPS calibration, and idle RPM setup. A good side effect was the ability to change idle RPM thereafter simply by adjusting the left idle screw without unbalancing the throttle bodies. I believe it accomplished those goals. In my own case, economy improved, idle stability is fine, never have any popping or sputtering or hesitation, and plenty of power, both before and after the mod's I made. Maybe I was just lucky, but I don't think so. I'm sure my bike could perform even better if it was remapped by an expert. I'll probably do that some time in the future, but for now, I'm quite happy.

 

Obviously, those that wish to continue methods which work for them are under no obligation to follow the procedure. Remapping fuel delivery or timing is outside the scope of the procedure, and squarely in the province of the professionals and skilled DIY's.

 

Go for it!

[Mike Stewart]

Hey David,

 

I went through and adjusted the tps to the 150mv with the throttle bodies disconnected and the the idle screw backed out. Please remember this was back in 2001 when there was not much information out on this fuel injection system. Once the throttle bodies were syncronized and idle set, the tps voltage on my bike was very low (I believe it was around 300mv). If I had set the tps voltage up to 520mv, I would have a really high idle speed. Now there are some variables that caused the tps. voltage to be lower (once the idle was set). The early bikes had a stall problem with the valves set to factory specs when hot, I used the Raceco valve lash specs. which gave the cam less overlap thus raising the idle speed 300+ rpm. With this valve lash, the bike also could idle down lower (which to me sounded better anyway, lope, lope, lope). So turning the idle speed down 300 rpm from the valve lash and then lowering the idle speed down to a rock solid 1000 rpm where it sounded so lovely, my tps voltage was lower. This was not a bad thing, I just had to have the right map for the PCIII.

 

This is the site to FIM which is what I used way back when for adjusting the tps. They have a great explaination of what the tps does and why to set the bypass screws all the way in. http://www.fuelinmoto.com.au/

 

Mike

 

 

 

Was your TPS voltage at idle below .5V? If so, than you were not using the method we created.

If a PCIII map is used, the bike should be tuned to the specs that the bike was mapped to.

Unfortunately people simply take there bikes to dyno for mapping without giving the bike a proper tuneup, and then they share their maps.

[dlaing]

Thanks for the reply, Mike.

Interesting. Your bike may have run similarly to ALdad's who also gets a high idle.

My bike is also a year 2000, but idles fine.

I do run the tappets set to .15/.20mm as opposed to the raceco .20/.25mm.

I do not think that should make such a difference that you can't use the air adjustment screws to correct. Probably something else is happening.

As for the air adjustment screws, FIM says to close when balancing, that the default is closed but to open and adjust to get the right CO reading and balance.

They also say, "tap the butterfly with your finger to ensure that the butterfly is completely closed against the body" but I believe you do want to be gentle with it. I don't think it is designed to take force the way it is at WOT where I assume there is some sort of stop.

And they say some other interesting stuff, like set it to 150mV exactly, rather than ±5mV.

I found that depending on how I seat the right throttle body, I get an inconsistent reading at completely closed throttle. I should measure the variation, but I recall is around ±5 or 10mV. I must verify, but that will vary by bike. If you get the mV set to exactly 150mV there should be less room for error.

I guess we need more people to test the procedure.

People with custom mapped PCIIIs, remapped ECUs and aftermarket ECUs might not get good results, but there is not much we can do for them.

But we should be able to figure out why some get a high idle following the instructions, assuming that is really what is happening.

[jimbemotumbo]

Going back and revisiting tune up info here. Still can't believe how useful this site is. Never open my Guzziology book anymore, though it remains a MUST HAVE.

 

I just wanted to add here, that in addition to the valve adjustment and TPS settings thoroughly discussed, I found proper TB balancing to be the key to getting my V11 to idle perfectly and run smoothly across the rpm range.

I think Ryland noted this at some point (apologies if I have that wrong) ... that balancing at higher rpms is not the best approach. I agree completely. Prob works well enough, but the best and most accurate technique is to balance at idle and at off-idle, just as the throttle plates are opening. This is much more accurate as the difference in airflow and vacuum between each side is a higher percentage at this opening than at any other opening.

 

I had a much smoother goose with this approach and minimized the chance of quickly overheating the motor.

Try it - you'll like it!

[raz]

And they say some other interesting stuff, like set it to 150mV exactly, rather than ±5mV.

I found that depending on how I seat the right throttle body, I get an inconsistent reading at completely closed throttle. I should measure the variation, but I recall is around ±5 or 10mV. I must verify, but that will vary by bike. If you get the mV set to exactly 150mV there should be less room for error.

Yes I think I have even seen someone claiming they set ±2 mV and while that can't harm anything, IMHO it simply can not be a good investment of time. Hello, it will jump 10 mV if your wife farts in the other end of your garden. It drifts 10ths of mV if you start the engine (it should not since there is a 5V regulator that doesn't care much if the input voltage is 11 or 14 volts. I guess it is due to ground offsets). Also, I don't think the OEM ECU's has a lot more resolution in their ADC's than Cliff's MyECU which is 10 bit. That means a resolution of about 5 mV. Spend two hours more to set it ±2 mV and the ADC will still read the same. Spend yet another 4 hours to set it to ±1 mV and the ADC will still read the very same. What is the point? It's like calibrating your spark plug gap to 1/1000 mm or your tire pressure to 0.01 psi. I may be wrong but I doubt it.

[dlaing]

Yes I think I have even seen someone claiming they set ±2 mV and while that can't harm anything, IMHO it simply can not be a good investment of time. Hello, it will jump 10 mV if your wife farts in the other end of your garden. It drifts 10ths of mV if you start the engine (it should not since there is a 5V regulator that doesn't care much if the input voltage is 11 or 14 volts. I guess it is due to ground offsets). Also, I don't think the OEM ECU's has a lot more resolution in their ADC's than Cliff's MyECU which is 10 bit. That means a resolution of about 5 mV. Spend two hours more to set it ±2 mV and the ADC will still read the same. Spend yet another 4 hours to set it to ±1 mV and the ADC will still read the very same. What is the point? It's like calibrating your spark plug gap to 1/1000 mm or your tire pressure to 0.01 psi. I may be wrong but I doubt it.

I am content to set my spark plugs to within 1/10 of a mm and I don't think I could set it much closer with the gauge I use.

Tire pressure is like a mood to me and I can vary by nearly 5PSI.

But TPS is the key to the first door on the search for the holy grail.

Within a minute I can adjust it to within ±2mV. It really is no big deal to set it that accurately. Setting it to ±0.5mV is tougher, but is doable within 5 minutes of hit and miss tightening.

Yes depending on how it is seated and whether engine is running or not, the TPS setting can vary greatly. If your wife farts, just be grateful you don't have one of those suede Tenni seats that absorb the odors.

Just because your wife's farts throw the sensor off by a ±10 millivolts does not mean you should give up on the pursuit of accuracy. Quite the contrary, because if you set it to 150mV±1mV and the seating error is, oh say, ±5mV and the state of charge error is, oh say, ±10mV, and the wife farting is ±10mV , then you could be as far off as ±26mV, while if you were setting it to ±10mV you could be off by as much as 35mV!

The 8 bit ECU increments it into 256 steps of about 19.5mV per step. (5000mV / 256 = 19.53125)

The fuel map has 16 rows of fuel cells. 5000mV / 16 = 312.5 mV

A difference of 9mV over 312.5 mV is less than 3% of a fuel cell, so yah it is not going to amount to much difference. But I know for a fact, that if I am by 60mV or less than 20% of a fuel cell, the bike will run in a noticeably miserable way. So, off by 3% won't be noticeable, but it is making a difference that the rider cannot perceive. Is that difference important? Probably not.

But I'll still take the extra minute or two to get it very close to 150mV

People who plan on doing custom dyno mapping should do the same, IMHO.

[dlaing]

I found that depending on how I seat the right throttle body, I get an inconsistent reading at completely closed throttle. I should measure the variation, but I recall is around ±5 or 10mV. I must verify, but that will vary by bike.

I verified, and setting it down very light vs. pressing firmly in differed by somewhere between 10 and 15mV.

BAAYMMV

[Dimitris]

Before I start I would like to apologize if the following questions of mine have already been stated by others and answered, but in this big topic of TPS adjustment I am lost so here it is:

 

I read carefully all the previous text (the procedure of adjusting the TPS and balancing the TBs). Then I opened the Guzzi Service Manual and read the procedure about the same subject.

I noticed the following differences:

Moto Guzzi Manual:1) Turn the Key to On (while the Axone is being connected)

2)Disconnect the connecting rod

3)turn the right throttle idle screw until 3,8 degrees are written on the software's screen

4)reconnect the connecting rod

5)fully close the bypass screws on both sides

6)bring the left throttle idle screw fully home (it means "screw fully in"??)

7)start engine

8)at 2000-3000 rpm (not at idling) check that the two cylinders air flow is balanced. If not turn the synchronization rod adjuster till the correct balancing

9)Grafually open both bypass screws so as to reach an idling speed of 1100+/-50 rpm.

 

10)If idling speed is not in specific limits: close the throttle duct (throttle angle 0°); (what does "close the throttle duct" means?)

· turn the ignition key to ON ;

· install the tester probes inside the throttle position

sensor connector across terminals “Q” and “R” and

check that the voltage reading is 150mV +/- 15mV.(does Guzzi means it should be done with the rod disconnected?)

· If the throttle position sensor reading does not fall inside

the above values, loosen fastening screws

and proceed to correct re-positioning.

 

 

Queries: 1)The first step of the forum's procedure is the final step of the Guzzi's procedure

2)Then, the forum's procedure sets the TPS (with the connecting rod connected) to .521mV, through the left throttle idle screw, while the Guzzi procedure sets it from the beginning through the right idle screw to 3,8 degrees (553mV), with the connecting rod disconnected.

 

 

Is it just the same procedure from the "reverse"? Or according to the many's people experience here, the conclusion is that the forum's procedure is more accurate?

Please help. As I will be waiting the VDST standard for my V11 LeMans I wanted your thoughts, opinions and explanations.

Thank you

 

Dimitris

[Ryland3210]

Before I start I would like to apologize if the following questions of mine have already been stated by others and answered, but in this big topic of TPS adjustment I am lost so here it is:

 

I read carefully all the previous text (the procedure of adjusting the TPS and balancing the TBs). Then I opened the Guzzi Service Manual and read the procedure about the same subject.

I noticed the following differences:

Moto Guzzi Manual:1) Turn the Key to On (while the Axone is being connected)

2)Disconnect the connecting rod

3)turn the right throttle idle screw until 3,8 degrees are written on the software's screen

4)reconnect the connecting rod

5)fully close the bypass screws on both sides

6)bring the left throttle idle screw fully home (it means "screw fully in"??)

7)start engine

8)at 2000-3000 rpm (not at idling) check that the two cylinders air flow is balanced. If not turn the synchronization rod adjuster till the correct balancing

9)Grafually open both bypass screws so as to reach an idling speed of 1100+/-50 rpm.

 

10)If idling speed is not in specific limits: close the throttle duct (throttle angle 0°); (what does "close the throttle duct" means?)

· turn the ignition key to ON ;

· install the tester probes inside the throttle position

sensor connector across terminals “Q” and “R” and

check that the voltage reading is 150mV +/- 15mV.(does Guzzi means it should be done with the rod disconnected?)

· If the throttle position sensor reading does not fall inside

the above values, loosen fastening screws

and proceed to correct re-positioning.

 

 

Queries: 1)The first step of the forum's procedure is the final step of the Guzzi's procedure

2)Then, the forum's procedure sets the TPS (with the connecting rod connected) to .521mV, through the left throttle idle screw, while the Guzzi procedure sets it from the beginning through the right idle screw to 3,8 degrees (553mV), with the connecting rod disconnected.

 

 

Is it just the same procedure from the "reverse"? Or according to the many's people experience here, the conclusion is that the forum's procedure is more accurate?

Please help. As I will be waiting the VDST standard for my V11 LeMans I wanted your thoughts, opinions and explanations.

Thank you

 

Dimitris

 

The manual's procedure ends with checking the TPS with throttle closed. If it is incorrect, one has to correct that, and start all over. The forum's procedure is designed to make progress step by step to avoid trial and error adjustment. Accurate voltage (degrees) measurements depend on the 150 mv basis. There is no advantage to going through the procedure, and then checking the 150 mv. That's a classic case of putting the cart before the horse.

 

To measure the 150 mv baseline, the right throttle plate must be fully closed. To ensure that is the case, the safe bet is to disconnect the connecting rod, back out the right idle screw, AND make sure the "choke" allows the throttle plate to fully close.

 

I believe that by "fully home" in the manual's procedure means out (this terminology also used on some machine tools). This puts the right idle screw in control. The problem with that is that the connecting rod linkage switches from compression to tension when coming off idle, so if there is any backlash, the synchronization between the two throttles will vary. The forum's procedure puts the left idle screw in control with the right backed out. That keeps the connecting rod in tension always, so backlash does not interfere with synchronization.

 

Stick with the forum's procedure is my advice. It's the result of detailed analysis and the contribution of several experienced Guzzisti's. There is the minimum of trial and error. Since the left idle screw is in control, you can also easily adjust idle speed in the future by simply adjusting that, without fear of upsetting synchronization.

[Dimitris]

Ryland,

 

thank you for your reply. Yes, I will stick with the forum's procedure.

 

"back out the right idle screw" means fully closed, am I right?

[dlaing]

Back out the idle screw means to loosen it so much that it has no effect on the throttle, so that the butterfly valve will fully close, unrestricted by the idle screw.

Beware the choke can also restrict the valve fully closing, so it too must be loosened.

[Dimitris]

Back out the idle screw means to loosen it so much that it has no effect on the throttle, so that the butterfly valve will fully close, unrestricted by the idle screw.

Beware the choke can also restrict the valve fully closing, so it too must be loosened.

1)So "back off the right idle screw" is the same with the "back out the right idle screw" which means "loosen the right idle screw" which in simple words means "turn it left??"

 

 

2)In the forum's procedure is written "Next open both air bypass screws to obtain the idle RPM at 1100 to 1200 while maintaining balance. Air bypass screws should be open 1/2 turn or more. If not, back off the idle screw to reduce the TPS voltage reading in steps of 15 mv and open the air bypass screws to compensate until they are opened 1/2 turn or more."

Which means "turn the left idle screw left"?

 

the reason I am asking these details is that I will try to do it all by myself for the fisrt time and I want to be accurate and correct so as to be sure that if somenthing goes wrong, what and where to look at...

 

Thank you in advance and excuse me if I am being tiring...

[dlaing]

1)So "back off the right idle screw" is the same with the "back out the right idle screw" which means "loosen the right idle screw" which in simple words means "turn it left??"

 

 

2)In the forum's procedure is written "Next open both air bypass screws to obtain the idle RPM at 1100 to 1200 while maintaining balance. Air bypass screws should be open 1/2 turn or more. If not, back off the idle screw to reduce the TPS voltage reading in steps of 15 mv and open the air bypass screws to compensate until they are opened 1/2 turn or more."

Which means "turn the left idle screw left"?

 

the reason I am asking these details is that I will try to do it all by myself for the fisrt time and I want to be accurate and correct so as to be sure that if somenthing goes wrong, what and where to look at...

 

Thank you in advance and excuse me if I am being tiring...

1) Yes, turn the right idle screw left, until it no longer effects the butterfly valve. Some permanently remove the right side idle screw.

 

2) IF the idle is too high when the TPS is set to 521mV and the air bypass screws are out less than half a turn, THEN turn the left idle screw out counter-clockwise (left) to reduce the TPS voltage reading in steps of 15mV.

You should turn the left idle screw counter-clockwise (left) enough to reduce the idle to less than 1200rpms and basically disregard the recommended 521mV.

Turning the left idle screw left or counter-clockwise will lower the TPS voltage reading at idle.

But beware that if you must set it below 500mV, there is a good chance it was not properly set to 150mV and you should double check your work, making sure right idle screw and choke are not preventing butterfly valve from fully closing.

Another possibility is that the idle could be too low without a couple turns out of air bypass. If two full turns out of the air bypass screws don't provide 1100RPMs or more idle, I believe it will be necessary to turn the left idle screw in clockwise (right) until the idle reaches 1100RPMs. Keep in mind that if the idle is too low it may indicate something else is wrong, such as valves being out of adjustment.

Does that make sense?

[Dimitris]

1) Yes, turn the right idle screw left, until it no longer effects the butterfly valve. Some permanently remove the right side idle screw.

 

2) IF the idle is too high when the TPS is set to 521mV and the air bypass screws are out less than half a turn, THEN turn the left idle screw out counter-clockwise (left) to reduce the TPS voltage reading in steps of 15mV. (meaning that if I turn both air bypasses 1/2 or more turns and the idle is still high, I will leave the air bypasses at that turns and back out the left idle screw only, till the correct idle indication appears, am I right?)

You should turn the left idle screw counter-clockwise (left) enough to reduce the idle to less than 1200rpms and basically disregard the recommended 521mV.

 

Turning the left idle screw left or counter-clockwise will lower the TPS voltage reading at idle.

But beware that if you must set it below 500mV, there is a good chance it was not properly set to 150mV and you should double check your work, making sure right idle screw and choke are not preventing butterfly valve from fully closing.

 

Another possibility is that the idle could be too low without a couple turns out of air bypass. If two full turns out of the air bypass screws don't provide 1100RPMs or more idle, I believe it will be necessary to turn the left idle screw in clockwise (right) until the idle reaches 1100RPMs. Keep in mind that if the idle is too low it may indicate something else is wrong, such as valves being out of adjustment.

Does that make sense?

 

Perfectly explained Dave! Thank you so much!! Your indications will proove very helpful! Just one more thing: How can I make sure that the choke is loosened (so as to be sure that the butterfly valve is closed)? I suppose that the level on the left handlebar should be in the upper position, correct?

[raz]

Perfectly explained Dave! Thank you so much!! Your indications will proove very helpful! Just one more thing: How can I make sure that the choke is loosened (so as to be sure that the butterfly valve is closed)? I suppose that the level on the left handlebar should be in the upper position, correct?

That is correct. The "choke" is really a fast-idle lever. First, follow the cable to the throttle body, look there when pulling the fast-idle lever and try to understand it's function. It is pretty straight-forward: the fast-idle is just a cam that moves the throttle exactly like the idle screw. There is nothing more to it. So when you back off the fast-idle lever you should also make sure that cam is completely backed off from influencing the throttle. If it does, there is a screw (head down) somewhere down there that you can use to adjust it. There is a good picture here somewhere, I'll try to find it and add it later.