low throttle opening glitch

[guzzista]

Asides from my preference for Mercury carb stix over the Twinmax I have tuned both my Calis and the Coppa straight from Jeffs procedure. To clear some other points, the TPS( both) ended at 550 MV running idle setting with the PC111 dyno tune, and as far as that goes there was a lot of fine tuning at all throttle opening percentages( from full throttle on down to 10% ) as well as under 10 percent dialing in (25 dyno passes with a near perfect AFR). At this point I have to rule out TPS problem as Hubert says its too unlikely that at 3400 miles they could both be corrupted. So now its time to back probe the ECU in relation to input sensors registering the proper values at the ECU side. I am thinking the starting point will be a temperature sesor, as the temp sensor holder has been changed to the brass(Quota) type and at running temps (ambient temp=70/75 F and a fully warmed engine is whre I am detecting most of the hiccups....pleae feel free to make suggestions...Cheers

[luhbo]

Regardless what in the end may come up as the reason for your actual problems: if your TPS now is set correctly according to the description Moto Guzzi gives and wich Jeff has proofen to be correct, then let your fingers off from the TPS. That's not written in bolt because I think I should tell exactly you what to do or not. It's because this is an adjustment done "once", comparable to the (fixed) adjustment of the camshaft, valve clearance or if you want the chassis geometrie.

 

Everything else may sound in a certain way "technical sophisticated" but is, well, not really common technical sense.

 

If you feel there may be something wrong with your TPS or its setting then check it according to what Jeff was so friendly to post on the mentioned site. Never just loosen the screws and turn the TPS 'till you think your engine runs better. Else you'll loose every solid ground this way and in the end possibly end up with the third TPS.

 

Fiddling with the TPS and selling this as a "secret solution" is unprofessional.

 

-----------------------------------

 

According to your last post it seems as if you are either already well supported or you personally know well what to do and how things work.

As Dave already has mentioned: why don't you just modify the specific area where the hickups appears? While working on my map I found that using an O2 probe/target to solve such transition problems is not 100% satisfying. Opening throttle is such a transition problem. I'd probably not so much enrichen the cells the engine passes but more those where the transition starts, in order to underlay some food for the trip where carbs relay on the acceleration pump.

 

If the PCIII allows it to overlay its own temperature correction map above the ECU one, than probably this is a point where your work could start also.

 

If the overall behaviour of the Guzzi is satisfying then a sensor is probably not the reason for the coughing. Also, the engine is new, so the timing chain and the shafts should not already suffer excessive wear what also could be a reason for such things.

 

Finally, to come to an end now (as the hollydays do also), have you compared it with another bike?

 

That's not my daily business, so please take it as my

 

Hubert

[guzzista]

All points are indeed well taken, and indeed 'tis a strange problem as it does not occur till warm running temp ( or at least what I perceive that to be), and then not always consistently. At this point I am grasping at straws... ... regarding the adding bits of fuel on the PC111 mapping, we actually did that , with no percieivable results while on the dyno( the glitch thing happened there too, and sporadically at that....As far as for the ECU, we went to using the stock ( not Titanio) because the bike actually behaved better on the road with it, and besides , the Power Commander was going to address fueling changes needed anyway...So back to what I learned in Automotive Fuel Injection training back in the 80's... time to back probe the ECU harness and verify input values...

[guzzista]

In order to track down the nature of the glitch at low/slow thrttle openings , I am going back to what was altered on this bike , and as some might recall, the camshaft wore prematurely on the left side exhaust lobe at 800 miles on the clock.Since it was put back together by the local dealer the glitch has been present. Now , trusting that the camshaft was reground properly( and based on the super precise work of Steve Hannigan at Progressive Automotive Machine I have no reason to doubt it).May there be a possibility that camshaft timing is slightly off or perhaps the chain was set just a bit slack that it may " confuse'' the magnetic position sensor and therefore the glitch would ensue when the throttle is turned slowly? If so, can that be checked with a strobe timing light or does the timing chest have to come apart.( I havent had a Chain type Guzzi timing chest open since 1986 so I am bit fuzzy on the way it looks in there, asides from viewing pictures). Would love to hear from folks who have dealt with setting up the V11 cam timing/ chain tension...Cheers

[Greg Field]

Augie:

 

Last week, my Billy Bob began running like you describe yours as running. I set the valves, synch'ed and balanced the TBs, hooked up the Axone, and confirmed that allwas properly set. I was getting a hint of cough while hooked up so I adjusted the Axone for +15 on the fuel at low throttle openings. This cured the coughing for two days.

 

Then on Sunday I went on a long ride two-up, and the problem gradually returned. Yesterday morning I think I found what is the root cause of the cough: A small but sure-to grow crack in the weld joining the two halves of my FBF crossover. That afternoon, Slug came in to get some stuff. I checked his FBF crossover and found it cracked, too, although his was cracking across the weld. You might check for cracks in your exhaust system . . .

[guzzista]

Thanks, Greg, I will Definitely check that!...Spoke with Brad (MGNA tech support) the other day, and after covering the probabilities , (in my case

[Greg Field]

The tensioner on a V11 is automatic. I do not see how a mechanic could leave it loose. It could have been put on out of time, though.

[Guest shadetree]

I found this discussion to be very helpful. I had a very difficult time finding the source of my part-throttle hiccup. After reading this discussion, I became suspicious of a failed TPS. After checking the CTS website http://www.ctscorp.com/automotive/datasheets/510.pdf for specs on the TPS, I thought I could test the overall resistance of my TPS (across terminals A and B ). I found mine to be about 3700 ohms. Based on the specs on the CTS website, which says the resistance should be about 1200 ohms, I concluded the TPS was bad.

 

The reason I'm posting this is to pass along what I've found. Not sure why, but the resistance of the PF3C TPS is probably not supposed to be 1200 ohms. I ordered the PF4C Harley Davidson replacement (27271-95) and even this new TPS had a resistance of about 2800 ohms. Since I had the new part, I put it on, made all the proper adjustments, and eliminated my problem. The Jackal runs like a gem again.

 

As a side note, my Jackal owner's manual came with a schematic. The TPS on the schematic is incorrect. It lables terminal B as being the wiper on the TPS. That's not corret, it is terminal C.

 

Thanks for sharing your experiences, folks. Your knowledge got me back on the road.

[Cliff]

Looking at their schematic on that PDF, it seems you are measuring R1 ( 3800 ) and do not have R2 (1700 ).

 

The interesting thing is R2 would have NO effect on what the ECU would read. In fact I can't see why its there as the only effect is to load the ECU's 5V supply.

 

So I don't think you have a TPS problem. I would put a voltage meter on the wiper and see how smoothly it follows the throttle movment.

[Ryland3210]

Here is the recently researched and quantitatively analyzed results of the contributions of several knowledgable contributors on TPS calibration and throttle synchronization. It works, is consistent with the known facts, and is straightforward to use.

 

IDLE TPS/THROTTLE BALANCING TUNING September 9, 2007

 

First make sure the TPS is calibrated to 150 mv at fully closed as follows: disconnect the connecting rod, back off the right throttle idle screw and choke cam (make sure the choke cable permits full retraction of the cam (it didn't on my bike), then loosen the TPS clamp screws and rotate if needed. + - 5 mv can be obtained with a little effort.

 

Next, close the bypasses, keep the right throttle idle screw backed off to put the connecting rod in tension, removing any backlash, and balance the throttles at idle using the connecting 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.

 

Now adjust the left idle screw for a TPS reading of .518 volts. + - .005 (corresponding to 3.4 degrees physical opening) 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.)

 

Next open the bypasses to obtain the idle RPM at 1100 to 1200 while maintaining balance. Bypasses should be open 1/2 turn or more. If not, back off the idle screw to reduce the TPS in steps of 15 mv and open the bypasses to compensate until they are opened 1/2 turn or more. Check balance at midrange RPM as follows:

 

A When checking balance at cruise RPM, make any fine correction needed using the connecting rod adjustment, then:

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

 

Option: Adjust the idle mixture trim potentiometer under the label of the computer for best idle quality, or use a gas analyzer if available. However, according to Guzzijack, "not an option on the V11Sport as it uses the 15M ECU - manual adjustment of the idle mixture potentiometer is only applicable to bikes with the P7/P8 or 16M ECUs - 15M idle mixture adjust is only possible via factory or aftermarket software."

 

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

[Greg Field]

FWIW, I got to ride today the Coppa Italia that is referenced at the start of this thread. It was left here to sell because the normal tuneup procedures failed to ever make it run right.

 

Micha, the service manager at Moto Intl., spent 15 minutes using his method and experience to give it a good tuneup, and now it runs perfectly. (His method was referenced in another thread, by Mr. Bean.) Today, I rode it on the freeway, in town, in traffic jams, and WFO, deliberately trying to get it to misbehave. I couldn't induce even a hint of a cough or sputtering, even when toodling along at 1500 rpm and very lightly transitioning off and on slightly with the throttle. It's now the smoothest running V11 I've ever ridden.

[dhansen]

Here is the recently researched and quantitatively analyzed results of the contributions of several knowledgable contributors on TPS calibration and throttle synchronization. It works, is consistent with the known facts, and is straightforward to use.

 

Do you start with a cold engine or at operating temp?

[Ryland3210]

Do you start with a cold engine or at operating temp?

 

It's more pleasant to start with a cold engine for calibrating the TPS and the steps up through step A. At that point, the engine should be warmed up, so the adjustments of the air bypasses for the idle RPM will be correct for a warmed up engine.