Throttle Position Sensor

[docc]

Why would we specify mV +/- "5" in paragraph one then recommend fine tuning (so to speak) in paragraph 4 of "15" mV? Seems like it should be the other way round.

 

Also, shouldn't there be a recommendation for valve adjustment as a first step?

[Greg Field]

I was just reading the instructions included with the Guzzi Ti pipes. They specify different tuning for the bikes with the front crossover and the bikes without the crossover. Fr the non-crossover bikes, it says set the TPS to 3.8 degrees +/- 0.1 degree, which it says corresponds to 550 mV +/- 5mV. For the crossover bikes it says set the TPS to 2.9 degrees +/- 0.1 degree, which it says corresponds to 465 mV +/- 5mV.

 

Perhaps this difference is meaningful and needs to be taken into account in the procedure set forth in this thread?

[luhbo]

I was just reading the instructions included with the Guzzi Ti pipes.....

 

I can't believe it.

 

You know the saying: If all else fails - read the fucking manual! ?

 

[Guest Phil_P]

FWIW, Todd Eagan at GuzziTech suggests using a baseline TPS Value of 238mV when using a Power Commander on a Sporti. I don't know if this has any relevance, but again it is an example of a displaced value being used to a particular end.

 

Just occurred to me that I don't know if Todd meant to apply this value at idle or with the link rod disconnected and the butterfly fully closed. I am making enquiries with Todd currently.

[dlaing]

Why would we specify mV +/- "5" in paragraph one then recommend fine tuning (so to speak) in paragraph 4 of "15" mV? Seems like it should be the other way round.

 

Also, shouldn't there be a recommendation for valve adjustment as a first step?

The plus or minus 5 mV is for the TPS setting below idle where the sensor is actually adjusted towards a 150 mV target.

The plus or minus 15 mV is set at idle and the sensor is not adjusted, the idle adjustment screws change the reading.

If you did not understand, than much of the audience of these instructions won't either.

Ryland designed it to be idiot proof if one follows the steps, but if people stray, and they probably will, they might start adjusting the wrong 'grub' screw.

I am beginning to think targeting 518 or 455 or 525 or 550 mV is a bad idea, especially after Greg's post regarding the Ti kit manual

This could be why Guzzi gave a range of 3.1° - 4.1°

What might work is to have them adjust the idle to oh say 1000RPM (I'd have to test that) and then bump it up to 1150RPM with air bypass screws, but that is not very scientific and it deviates from the manual

 

Valve adjustment is a good idea. I went back and modified the instructions

[Ryland3210]

Why would we specify mV +/- "5" in paragraph one then recommend fine tuning (so to speak) in paragraph 4 of "15" mV? Seems like it should be the other way round.

 

Also, shouldn't there be a recommendation for valve adjustment as a first step?

 

The difference is that the closed throttle adjustment is vital to establish the accuracy of the TPS signal to the ECU, whereas the reduction of the idle throttle position in 15mv steps is merely to permit the air bypasses to open at least 1/2 turn. It could just as well be 10 mv steps or 20 mv steps.

 

dlaing has included your recommendation on valve adjustment. I don't seriously object, but it's a deviation from the purpose of this procedure. One could also suggest checking spark plugs and timing, which would also be deviations, etc., etc.

 

 

I can't believe it.

 

You know the saying: If all else fails - read the fucking manual! ?

 

 

In this case, the manual(s) have not been very helpful.

 

The variation and inconsistencies in the various instructions, opinions, manuals is exactly why this investigation into a clear and useful procedure was started.

 

 

FWIW, Todd Eagan at GuzziTech suggests using a baseline TPS Value of 238mV when using a Power Commander on a Sporti. I don't know if this has any relevance, but again it is an example of a displaced value being used to a particular end.

 

Just occurred to me that I don't know if Todd meant to apply this value at idle or with the link rod disconnected and the butterfly fully closed. I am making enquiries with Todd currently.

 

Another example of ambiguity and points out the need for a dependable and clear procedure.

 

If the 238 mv is intended for the throttle closed TPS voltage, it will enrichen the entire range.

If the 238 mv is intended for the idle TPS voltage, it will lean out idle and low throttle opening conditions.

But then the Power Commander, as I understand its function, can be used to override either condition.

 

 

I was just reading the instructions included with the Guzzi Ti pipes. They specify different tuning for the bikes with the front crossover and the bikes without the crossover. Fr the non-crossover bikes, it says set the TPS to 3.8 degrees +/- 0.1 degree, which it says corresponds to 550 mV +/- 5mV. For the crossover bikes it says set the TPS to 2.9 degrees +/- 0.1 degree, which it says corresponds to 465 mV +/- 5mV.

 

Perhaps this difference is meaningful and needs to be taken into account in the procedure set forth in this thread?

 

See my comments on Todd Eagan's suggestion, and my earlier comments on the interaction between idle TPS and air bypass turns open.

 

I see no reason to change the draft of September 27th.

 

 

The plus or minus 5 mV is for the TPS setting below idle where the sensor is actually adjusted towards a 150 mV target.

The plus or minus 15 mV is set at idle and the sensor is not adjusted, the idle adjustment screws change the reading.

If you did not understand, than much of the audience of these instructions won't either.

Ryland designed it to be idiot proof if one follows the steps, but if people stray, and they probably will, they might start adjusting the wrong 'grub' screw.

I am beginning to think targeting 518 or 455 or 525 or 550 mV is a bad idea, especially after Greg's post regarding the Ti kit manual

This could be why Guzzi gave a range of 3.1° - 4.1°

What might work is to have them adjust the idle to oh say 1000RPM (I'd have to test that) and then bump it up to 1150RPM with air bypass screws, but that is not very scientific and it deviates from the manual

 

Valve adjustment is a good idea. I went back and modified the instructions

 

Keep the faith, dlaing. In my book the most recent draft of th 27th is fine. So far, these last minute comments are rehashing issues already considered and resolved.

[Greg Field]

Well, just FWIW, I think the manual is wrong and that Guzzi has things set up for different tuning between the bikes with front crossover and without. They just F-ed up in not doing an update. That manual is full of such F-ups. The ECUs supplied with the Ti kits are different for each, after all. Plus, Guzi is very specific in the differences for setup between the two. Given that, I think it extremely unwise to ignore the difference when designing your procedure. I can understand the desire to have "one procedure," but I think the reality is that there isn't just one.

[Ryland3210]

Well, just FWIW, I think the manual is wrong and that Guzzi has things set up for different tuning between the bikes with front crossover and without. They just F-ed up in not doing an update. That manual is full of such F-ups. The ECUs supplied with the Ti kits are different for each, after all. Plus, Guzi is very specific in the differences for setup between the two. Given that, I think it extremely unwise to ignore the difference when designing your procedure. I can understand the desire to have "one procedure," but I think the reality is that there isn't just one.

 

Good point, but look at the numbers:

According to Magnetti Marelli's chart for the TPS, in the first 30 degrees of throttle opening, the transfer function is .1061 volts/degree. This results in the following table:

Degrees Voltage

2.9 .458

3.4 .511

3.6 .532

3.8 .553

 

Now the manual's 550 mv is pretty close to 553, but its 465 mv is more than the 5 mv tolerance away from 458. The manual's credibility is suspect.

 

Now if you look at the fuel delivery mapping, the difference between 2 degrees and 4 degrees is small. To review once again, we have figured out that the idle setting of TPS is compensated for by the air bypass settings, and that it only affects mixture at idle, and the first few degrees of throttle opening just off/idle at most. Therefore the effect of the 2.9 degree spec is to lean out the idle and just off/idle mixture relative to the 3.8 degree spec and vice-versa. To see how little this effect is, have a look at the fuel map.

 

So here's my suggestion:

Instead of using the previous measured data on TPS versus angle which is only based on one sensor, let's use the manufacturer's ratio and the table above. Since there seems to be common ground on 3.4 and 3.6 among several sources, let's use 3.5 degrees as a target for the amateur. That equates to a voltage of 521 mv. Anyone using that as a target will not be far off the ideal. We can also include the table above for those who wish to follow "professional" recommendations.

[dlaing]

I was looking for the specs on the TPS and came across an interesting article on the TPS PF 3C

http://www.guzziclubfiorenza.it/sito/Poten...lunga_storia%29

The article is in Italian.

Google translation seems to indicate that the Fiat Punto uses the PF3C and cost is about 40 Euros.

Of course my interpretation of the translation could be wrong and maybe it is a PF2C or something that won't work well

So perhaps there is no need to go to the Harley PF 4C to save a few bucks.

Of course the profit made by buying one from Guzzi for a much higher price should help keep Guzzi in business.

BTW where are the specs?

[Guest Phil_P]

I get the feeling that the Fiat part wasn't entirely successful and that one problem with the Fiat TPS was that it didn't have slots to allow adjustment and that they had to cut some. It looks like they resorted to the original part after giving it a good dose of some form of switch cleaner.

 

I may have misread it of course, and I intend making some enquiries at my local Fiat specialist.

[v11cafe]

I was just reading the instructions included with the Guzzi Ti pipes. They specify different tuning for the bikes with the front crossover and the bikes without the crossover. Fr the non-crossover bikes, it says set the TPS to 3.8 degrees +/- 0.1 degree, which it says corresponds to 550 mV +/- 5mV. For the crossover bikes it says set the TPS to 2.9 degrees +/- 0.1 degree, which it says corresponds to 465 mV +/- 5mV.

 

Perhaps this difference is meaningful and needs to be taken into account in the procedure set forth in this thread?

I bought a set of Guzzi Ti pipes and there are no instructions included.Can you post it if you have it???

Guzzi manual for v11 cafe sport says 3.8 degrees +/- 0.1 degree TPS, but you say the instructions say

2.9 degrees +/- 0.1 degree for bikes with front crossover.

 

Hope we find a clue

[Ryland3210]

OK, here is another draft, hopefully taking everyone's concerns into account (which may be an imporssible dream, but worth a shot):

 

IDLE TPS/THROTTLE BALANCING TUNING

DRAFT September 30, 2007

For the following V11 Moto Guzzi motorcycles, made from 1999-2006

V11 Sport, Le Mans, Rosso Mandello, Scura, Tenni, Cafe Sport, Rosso Corsa, Nero Corsa, Naked Ballabio, and Coppa Italia.

 

If you suspect the valves need adjusting, do that first. Here is a link to some good instructions:

http://www.geocities.com/motoguzzi1064/Guz...alvesTorque.htm

 

Then make sure the TPS is calibrated to 150 mv at fully closed as follows:

 

Disconnect the synchronization rod at the ball joint on the right side (the side with the TPS sensor), back off the right throttle idle screw using a 2.5mm hex key, and back off the "choke" cam (make sure the choke cable permits full retraction of the cam (it didn't on my bike).

 

Turn on the ignition key, but do not start the bike. Measure the voltage difference between the two outer wires of the TPS. If the voltage is not 150 mV ±5 mV, then loosen the TPS clamp screws and gently rotate it as required. Be careful not to force it against the TPS’s internal stop in the direction of reducing the voltage, which could damage it. Plus or minus 5 mV can be obtained with a little effort.

 

To do the next step, you will need to connect a vacuum manometer (e.g. mercury stick) to each of the two ports on the intake fittings next to the cylinder head. These are normally connected together with a hose, which is to be temporarily disconnected.

 

Next, close both air bypass screws, reconnect the synchronization rod, but keep the right throttle idle screw backed off to put the connecting rod in tension, removing any backlash, and balance the throttle body vacuums at idle using the synchronization rod adjustment. Screw in the left throttle idle screw if the idle is too low to maintain. Do not use the choke for this purpose, because that would put the connecting rod in compression, introducing backlash, causing the throttle bodies to go out of balance.

 

Now adjust the left idle screw for a TPS reading of .521 volts. + - .005 (corresponding to somewhere between 3.4 and 3.6 degrees physical opening, as read by the optional diagnostic software). This accuracy can be obtained with a little effort. (Some riders have been known to also subsequently physically readjust the TPS (not the idle screw) to lean or richen the entire throttle range. However, loosening its screws and offsetting the TPS to a higher voltage, e.g. .539, will fool the ECU into adding more fuel, but it will also fool the ignition timing table. See also the note at the bottom under “Options”)

 

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.

 

Check balance at 2000 - 3000 RPM as follows:

A When checking balance at 2000 - 3000 RPM, make any fine correction needed using the synchronization rod adjustment, then:

B. Check balance at idle RPM. If OK, go to step C, if not, rebalance at idle using the air bypass screws, and go back to step A.

C. Disconnect the voltmeter and manometers. Replace the hose connecting the two intakes.

 

That completes the procedure.

 

Once this procedure is completed successfully, future minor changes in idle speed can be made simply by adjusting the left throttle idle screw. Since the throttle bodies have been balanced, backlash between them has been eliminated, and air bypass screws have been properly adjusted to maintain balance at idle, these should be stable for many miles.

 

Options:

Use a gas analyzer if available to set the CO level.

Use a diagnostic tool or diagnostic software such as Axeone or TechnoResearch's VDSTS to adjust the fuel trim, check throttle angle, RPM, and more.

 

 

The setting of .521 volts is in the middle of the range of published settings, and has been found to be reliable for stock motorcycles. However, for those who wish to follow specific instructions in their aftermarket parts, Moto Guzzi owners or service manuals, particularly for modified motorcycles, the table below shows the TPS voltage corresponding to various opening angles per the Magnetti Marelli OEM TPS specification. For other settings, here is the formula: 0.1061 volts/degree + 0.150

 

Degrees Volts DC

2.9 .458

3.4 .511

3.5 .521

3.6 .532

3.8 .553

4.0 .574

4.1 .585

[raz]

Shouldn't this be called 'the TPS report' ?

 

[Guest Jeff in Ohio]

OK,

 

let it be known, I made the MPH chart using a volt meter and the Factory Diagnostic Software Tool. Of course there is error in the MPH chart. The 15M ECU is an 8 bit digital system. That means it splits the incomming analog voltage signal comming from the TPS into 256 steps (2 raised to the 8th power). Knowing that the system is a 0-5 volt system, this yields that each step in the ECU is about 19.5mv (5 volts divided by 256 steps). Soooooo.... The ECU does not register a degree change on the software untill it sees a change of 19.5mv from the TPS. So, knowing this is the case, of course there is some error in the chart I made for MPH. I twisted the throttle open untill I saw a degree change on the software and noted the voltage. Was I at thebeginning of that 19.5 mv change, in the middle, or at the end? Who knows. It's all close enough anyway.

 

The Marelli chart that I obatined shows the TPS to be made of two linear sections. Someone even took a TPS apart and you can plainly see this on it's internal construction also.

 

Anyway, the procedure I wrote up years ago with the 'around 525mv' is based on all of the above and has worked well for lots o' people. 'Around 525' means you could probably be 20 mv either way because of the whole 8 bit system thing described above.....

[dlaing]

OK,

 

let it be known, I made the MPH chart using a volt meter and the Factory Diagnostic Software Tool. Of course there is error in the MPH chart. The 15M ECU is an 8 bit digital system. That means it splits the incomming analog voltage signal comming from the TPS into 256 steps (2 raised to the 8th power). Knowing that the system is a 0-5 volt system, this yields that each step in the ECU is about 19.5mv (5 volts divided by 256 steps). Soooooo.... The ECU does not register a degree change on the software untill it sees a change of 19.5mv from the TPS. So, knowing this is the case, of course there is some error in the chart I made for MPH. I twisted the throttle open untill I saw a degree change on the software and noted the voltage. Was I at thebeginning of that 19.5 mv change, in the middle, or at the end? Who knows. It's all close enough anyway.

 

The Marelli chart that I obatined shows the TPS to be made of two linear sections. Someone even took a TPS apart and you can plainly see this on it's internal construction also.

 

Anyway, the procedure I wrote up years ago with the 'around 525mv' is based on all of the above and has worked well for lots o' people. 'Around 525' means you could probably be 20 mv either way because of the whole 8 bit system thing described above.....

Thanks for charts at MPH and the write ups here and at Guzzitech.com.

Without your work, we might not be in the dark but would probably still be reading by candlelight, if you know what I mean.

Have you thought much about varying from the 525(521)mV reading, based on the what is in the manuals?

(Manuals have recommendations of 3.1-4.1° 3.2-3.6° and 3.7-3.9° as well as two different recommendations for Titanium Muffler/Race ECU kit, depending on whether or not they have the front balance crossover)

My thoughts (and probably Ryland's, too) are that it does not matter too much and that recommending 521mV should make just about everybody's bike run well.

I still want to verify by tuning it at 3.1° and 4.1° and see if it makes a noticeable difference.

I have tried the map on the Ti ECU and did not like how it ran at lower RPMs, so it may be important to get that ECU set up to the recommendations that Greg Field posted.

 

Shouldn't this be called 'the TPS report' ?

 

"Ah! Yeah. It's just we're putting new coversheets on all the TPS reports before they go out now. So if you could go ahead and try to remember to do that from now on, that'd be great. All right! "

--Dom Portwood (Office Space, the movie)