Throttle Position Sensor

[Bruce Reader]

Brad at Moto One also speaks about some changes to the Ducati 900 mie idle throttle position around 2000 (2.4 to 3.1deg) Perhaps this relates to Euro 1 to 2 or 2 to 3 emissions stuff or something else. Interesting he points out that the throttle angle/tps is increased to something similair to our basic setting on the forum and the Guzzi manual. Some of the high idle issues may relate to my point mentioned above or the right side throttle body shaft air suck.

 

Brad makes a good point in relation to tuning the bike in regards to idle trim, CO output etc. Some of us are doing this blind in regard to idle trim and CO output. My bike developed a stumble at low revs and idle problems after performing well (1 year or so)post tuning at Moto One. I have had fuel and crud build up on the lower shaft nuts on the throttle bodies over time for several years (including 2 events of the return spring not working due to build up-fixed with a solvent spray).

 

When i decided to give tuning a go at home i cleaned the throttle bodies externally -(possibly opening an earlier plugged air leak in the right throttle body) then followed the forum instructions. The bike ran very well - balanced etc- no pinking etc but my idle was 1600 rm with half turn out of air bleed left and right.

Note- my rhs tb air bleed was 1/4 out and my left 1/2 turn out before i started.

 

I have also used the other method disregarding closed mv reading (Michas ?) and runs well but a 20% loss in terms of fuel economy- previous 16km/ltr- now 14km/ltr. Air bleed 1 turn out left and Right.

 

I now need to go back and check a few things-

 

a. the rubber shaft seals

 

b. the idle trim setting

 

c.any valve changes- eg wear or out of setting- this cam is my second and note possibly a Breva cam replacement of the original which had wear issues. The bike was running fine with this cam and tuning for some time.

 

Cheers

 

Bruce

[dlaing]

I think these instructions might take care of the issue of high RPM at idle following forum instructions. The Moto One method probably would, too.

set tps zero angle 150mv key on/eng off everything disconnected,

then set RITS at 465mv (just a start value) ....and disconnect multimeter,

....connect throttle balancer, and balance with LITS..if idle rpm is low

increase RITS..balance again with LITS.....and so on until u r about 1000rpm idle

and balanced.

Now connect rod. and do part throttle balancing with rod screw (bypasses closed )and

balance finally at idle by opening the bypasses.

We need a more lengthy set of instructions that includes cracked or loose rubber manifolds, worn leaky butterfly shafts, gummed up return springs, etc.

If air leaks the rpm will be higher at a given idle TPS voltage.

Other issues such as valves out of adjustment, bad compression, and model variations throw off the relationship of TPS voltage to idle rpm.

The forum instructions do cover balance by air bypass screws, but we need to better cover it better, so that air leaks and other variations can be better handled.

And if we all had dual channel CO meters, and software to access the trim, the world would be a happier place.

[arek]

I am about to do the procedure, and after going through the your instructions, I have one question - after everything is done, the right throttle idle screw will remain backed off completely? The right throttle will remain in place at idle by the tension on the the synchronization rod. Or should there be an additional step to disconnect the synchronization rod after the desired voltage is set at idle by the left throttle idle screw adjustment, and match the voltage by screwing in the right throttle idle screw? Thanks.

[dlaing]

I am about to do the procedure, and after going through the your instructions, I have one question - after everything is done, the right throttle idle screw will remain backed off completely? The right throttle will remain in place at idle by the tension on the the synchronization rod. Or should there be an additional step to disconnect the synchronization rod after the desired voltage is set at idle by the left throttle idle screw adjustment, and match the voltage by screwing in the right throttle idle screw? Thanks.

Our instructions recommend keeping the right throttle idle screw off completely. The right throttle will remain in place by tension on the synchronization rod.

The benefit of doing it that way is that the balance is better maintained when transitioning from idle to giving it throttle.

But there are counter-arguments to this.

There is more flex between the left screw and the TPS, so if you close the throttle ten times, you will get several different voltage readings at the TPS, but if you set the right screw also, the throttle closing will get a more consistent TPS voltage reading at idle.

The difference between the two methods is small, at least theoretically. In practice I am sure we will see 10HP gains (just kidding!)

If the idle screws were loctited in, I could see how it would be beneficial to lock down the two idle set screws so that two TBs would rest consistently at idle, in balance, with a more consistent TPS reading.

But I can also see that setting the right idle screw causes the left cylinder to pull harder initially.

Six of one, half dozen of the other as far as I am concerned.

We wanted simple instructions, so that the left screw only is what we came up with.

Instructions are here:

http://www.v11lemans.com/forums/index.php?showtopic=12204

[Anthony]

Good idea, docc.

 

Here's another procedure from the How To section, which seems to be technically thorough. However, note that the "My comments" are my personal edits, for my own file.

 

I would like to see a response to these comments, and any superseding understanding of Jeff's comments with the result being a comprehensive, thorough, anc accurate procedure/explanation.

 

Jeff in Ohio, April 13, 2004

“How to Balance the Throttle Bodies, with pictures, even”, in the How To section

 

allow me to offer these comments. the air bleeds are not there to adjust the idle mixture, that is what the CO trimmer is for in the factory software. Idle Mixture Screw: This is located in the computer under the rubber plug, which is covered by the Moto Guzzi labeled decal. It's a tiny screw on a trim potentiometer; use an eyeglass screwdriver. The full range of adjustment is 270 degrees and clockwise is leaner, CCW is richer. The air bleeds are to be used for idle speed adjustments. A more proper procedure is to:

 

1. set TPS with everything backed off and disconnected (My comment: this means with the right throttle butterfly closed, idle screw, connecting rod and choke cam backed off) to the correct 150mv value

 

2. balance throttlebodies using the throttle stop screws with the air bleeds screwed in and the linkage unhooked so that the TPS reads the correct value as indicated in the service manual (3.4 deg +/- .2 deg, roughly 500-525mv) This is so the ECU is now set up so it knows the throttle plates are in the correct position for idle so all the mapping vs. throttle angle works out correctly. Your idle at this point will probably be be BELOW 1000 rpm and rather rough. (My comment: An alternative is to first balance the butterflies with the air bleeds screwed in, but then set the airbleeds to ½ turn open to raise the idle speed to 1100 RPM and check the TPS reading.)

 

3. open airbleeds and use them to balance to achieve the final appropriate idle speed of around 1100 rpm. Your idle should have smoothed out now. The factory manual goes out of its way to state the airbleed screws are there to set your idle speed. You will find that your airbleeds will end up being around 1/2 turn open as stated in the factory manual.

 

4. Adjust the linkage so that it can be reassembled without having to open one of the throttlebodies more than the other - that is, the socket on the link should drop back on the ball without having to move anything.

 

5. NOW rev your bike up and synch using the white knob. You might find that of you took great care in step 4, that the white knob has to be turned very little if any at all.

 

6. NOW use the factory software and a CO meter to set the correct idle mixture. In a pinch without a CO meter, you can set the trim like a mixture screw on a carb by adjusting it up and down to achieve the best quality of idle. That is why the software is needed - it is used to set the idle mix, NOT the airbleeds.

 

Great information!

 

I have a spin-off question that I hope you can help me with. I need to use my choke to keep the bike idling. This is a recent development. I have a PowerCommander, that I have not touched, and the bike runs great, except for the idle.

Can I use the idle mixture screw to set the idle speed?

[Kiwi_Roy]

Has anyone tried varying the throttle position mV while riding?

It seems to me an easy thing to make up a pot to allow offsetting the mV +/- say 20 mV

This would allow you to stop and move the sensor by an equivalent amount.

Just a thought

Roy

[docc]

This simple procedure, or its variants (deviants?) remains the single best medicine to tune a V11. Over the years it has cured more weirdness and woes in the Guzzi than any other single approach.

 

Tune early and often!

[Guest ratchethack]

Has anyone tried varying the throttle position mV while riding?

It seems to me an easy thing to make up a pot to allow offsetting the mV +/- say 20 mV

This would allow you to stop and move the sensor by an equivalent amount.

Just a thought

Roy

Very nearly, Roy. I temporarily installed a variable resistor in series with the head temp sensor, which works through a similar ECU algorithm and ECU map as the TPS, and likewise controls A/F. It allowed me to adjust A/F "on the fly".

 

 

Variable A/F on the fly

 

I experimented extensively with it a year ago in Winter, when it was cold and rainy here, I couldn't ride much, and I had the time. A search on "head temp sensor" will find my carefully documented results as they happened, punctuated by an absolutely astonishing record of daily baseless, empty ridicule and idiocy from the usual Forum weasels and ferrets, whose grip on reality is apparently so fragile, that they somehow believed themselves threatened by my experiments, which were all clearly beyond their ability to comprehend. It was truly one of the most amazing displays of imbecilic public behavior I have ever seen on any Forum. The thread was eventually locked due to the vermin infestation.

 

In any event, ignoring all the status quo GROUPTHINK, arrested development, and diseased egos was easily enough done. The results of my experiments led me to come up with an alternative head temp sensor and holder that has worked far better than the OE unit (particlularly in hot weather) and has repeatedly returned a consistent 10% better mileage on my test benchmark "inspired" mountain riding loop, under all temp conditions. I've been riding with it in its final form ever since, and have been pleasantly surprised by the consistent improvements and enhanced enjoyment of riding. My interest in fiddling with it in the first place was based on the similar experiments of a guy who gave me the idea years ago. My results were duplicated as reported here by at least two others on this Forum.

 

Since the topic was dragged into the gutter by the vermin, and the vermin-attracting stench is likely still prohibitively fresh a year on, the topic is likely to be a similar draw for the same rodents (still here) today. So sadly enough, I can't recommend a re-opening of the topic. But If you're sincerely interested, I'd be more than pleased to give you my perspectives on the process and results via PM or email.

[gstallons]

Has anyone tried varying the throttle position mV while riding?

It seems to me an easy thing to make up a pot to allow offsetting the mV +/- say 20 mV

This would allow you to stop and move the sensor by an equivalent amount.

Just a thought

Roy

 

 

I don''t think you could do this "safely". If you were going to do this, you would use a rheostat, not a potentiometer in series with the signal return wire or in series with the voltage reference signal.

[Kiwi_Roy]

I don''t think you could do this "safely". If you were going to do this, you would use a rheostat, not a potentiometer in series with the signal return wire or in series with the voltage reference signal.

Rheostat, Potentiometer they are used to mean the same thing, a variable resistor in other words.

I plan on doing this test shortly, I have adjusted the sensor acording to this multi page post (100 pages to print) and balanced the throttle bodies.

I will make a small box that offsets the mV to simulate re-positioning the sensor (zero Elevation/Supression in Instrumentation speak), mounted near the left hand grip where it's convenient to reach.

I haven't quite figured it all out yet but I expect it will take a while to compare different settings.

 

I removed my Power Commander for the test, once I get it running as good as possible I will re-install. I may be wrong but I suspect the Commander may do the same thing (zero shift).

 

Will report back

 

BTW - it's a pity that this important thread has so many posts to wade through, can someone not abreviate it or appoint a guru to make a simple one page replacement to pin in it's place, just saying that's all.

Regards

Roy

[raz]

can someone not abreviate it or appoint a guru to make a simple one page replacement to pin in it's place, just saying that's all.

 

They did! This thread is the discussion that led to http://www.v11lemans.com/forums/index.php?showtopic=12204

[gstallons]

Rheostat, Potentiometer they are used to mean the same thing, a variable resistor in other words.

I plan on doing this test shortly, I have adjusted the sensor acording to this multi page post (100 pages to print) and balanced the throttle bodies.

I will make a small box that offsets the mV to simulate re-positioning the sensor (zero Elevation/Supression in Instrumentation speak), mounted near the left hand grip where it's convenient to reach.

I haven't quite figured it all out yet but I expect it will take a while to compare different settings.

 

I removed my Power Commander for the test, once I get it running as good as possible I will re-install. I may be wrong but I suspect the Commander may do the same thing (zero shift).

 

Will report back

 

BTW - it's a pity that this important thread has so many posts to wade through, can someone not abreviate it or appoint a guru to make a simple one page replacement to pin in it's place, just saying that's all.

Regards

Roy

 

Roy,

you are sort of right and sort of wrong.

Please see this description or explanation in the link below to see the difference. Google the word potentiometer and rheostat to see the difference.

http://answers.yahoo...10075133AAMoFTz

[Kiwi_Roy]

Roy,

you are sort of right and sort of wrong.

I stand corrected, it's sort of like the Alternator Generator argument for AC

Potentiometer is more meanigfull for my project, I'm changing the Potential

BTW,

I tried it out over the weekend but my bike is running so rich that even subtracting 250 mV didn't seem to effect it.

Yes, I did the closed throttle 150 mV adjustment (460 mV at idle 4800 odd at WOT).

I don't think I have the little screw on my ECU.

Regards

Roy

[docc]

I stand corrected, it's sort of like the Alternator Generator argument for AC

Potentiometer is more meanigfull for my project, I'm changing the Potential

BTW,

I tried it out over the weekend but my bike is running so rich that even subtracting 250 mV didn't seem to effect it.

Yes, I did the closed throttle 150 mV adjustment (460 mV at idle 4800 odd at WOT).

I don't think I have the little screw on my ECU.

Regards

Roy

 

 

No, no little screw on your ECU. Your CO trim will have to be adjusted with a software interface (Axone or VDSTS). As delivered, my Sport was " -27"; bringing it to "0" brought the idle up several hundred RPM and made it more stable. Fuel economy did not change.

 

460 mV seems low for idle. Another advantage to the software interface is to read the RPM from the crank sensor and compare to the indicated RPM on the tachomater. Early (Veglia) tachs often read 300-500 RPM high. The result is that you should tune with the correction in mind. In other words, a 300 RPM high indication would dictate you set your idle at an indicated 1450.

 

Happy idle=happy oil=happy charging.

[ponti_33609]

 

 

Early (Veglia) tachs often read 300-500 RPM high

EXACTLY!