"pinging" when accelerating/Use of moly in gear bo

[RichMaund]

Folks

I have read much about this topic both here and in the MGCL. My bike has occassionally pinged under acceleration. I have done much to reproduce it to see under what cirumstances it occurs. Here's my theory:

At lower rpms the engine is out of the best part of the power band and airflow is only moving slowly in the intake system. When you wack the throttle wide open this is what I believe is happening to the dynamics of the system. The airflow crashes dramatically. You have leaned the mixture due to admitting so much air to the tract when the engine isn't ready to accept it. You have reduced the flow velocity and the ram air effect the higher (Though still slow.) flow rate gave itself before you whacked the throttle.

I have tried this at progressively higher rpms and the problem becomes reduced and eventually eliminated as I try it at higher rpms. Reason? Because the engine is progressively into the better part of the powerband, intake flow rates are becoming higher and the difference in flow rates between WFO at 4k rpm and at 6k rpm means that "crashing" the airflow is much less of a problem at higher rpms.

And what of the people who ask "Why didn't this ever happen on my Kawazukida?"? Those bikes probably had CV Carbs. Next best thing to fly by wire for the intake airflow. You can whack the throttle open all you want, but the slide will only rise and allow more flow as the engine is ready for it. That rate gets set by the engineer who designed the system!

My Cali1100i could be made to ping under load and so could my 1989 carbed Mille' GT. Hell, my Ural can do it. But thinking back on it, none of my CV equipped bikes have had the problem.

I suggest the cure is more careful throttle management. "Roll" the throttle on vice whacking it open. Make for smoother transitions vice sudden ones. I purposely rode my bike this way, smooth control inputs, and it loved it.

If I wanted to pass a car, drop down a gear and roll it on! Whereas whacking it in gear just resulted in a unhappy engine.

It's not so much a problem with the bikes as us needing to learn its characteristics to better use it's capabilities.

Moly:

This bike was already the smoothest shifting Goose I have ever run. A thousand miles ago I used a moly additive with my gear oil change. Same as I use in the rear drive. I had wondered about doing this as it improved every 5 speed Guzzi gear box I have ever owned. I can honestly say that it improved my 6 speed in this bike too. I was laughing in my helmet today realizing what a light touch I am using on the shifter. Light and smooth as silk! Will it violate my warranty? Hell if I know. I'll be damned if I ever let a Dealer take my bike in for major repairs ever again. I lost the bike for almost 6 weeks for a transmission oil leak a year ago. The job kept getting pushed aside to get customers in whose problems were more minor. His employees ratted his behavior out to me about it. I finally had to heart to heart talk with him to get action on my bike. He is still my favorite Guzzi shop within a day's ride. But he sometimes spreads himself thin and can't seem to say "no" when customers need help NOW! In that shop, the squeaky bearing gets the grease vice "first come, first served". I could have done it myself in one long day's work. Since I promised myself that I'd never ask for anything but parts under warranty anymore, I went ahead and used it. Sweet!

So, what do you think? Does my theory have merit?

[emry]

I would agree Rich. If you have ever ridden a flat slide carbed bike not only can you get them to ping but you also can get them to stall with over zealous throttle application. (But that is due to the decreased air speed and the resulting lack of fuel atomization in the venturi.) But if you compare fuel injected twin to fuel injected twin, My TL1000 never had any problem. Idle to WOT and it always had immediate response, without any trace of detonation. But the TL used a MAP (manifold absolute pressure) sensor to determine engine load. This enabled it to enrichen the fuel curve or retard ignitoin timing during rapid throttle transitions which causes a lean condition, accelerator pumps on the flat slide carbs tried to do the same. (minus the igniton retard of course.) The V11's have only a BARO sensor to adjust for altitude unfortunately. Much as you said a more careful application of throttle can "cure" the problem or at least not cause the condition to arise. But in such a low performance application I would believe that some careful tuning (PCIII, fuel and igntion mapping) should sort out the problem.

 

But here is another thought that is often overlooked, the squish clearence. Does anyone know what the V11's 2002 and older are using? I noticed that they upped the compression on the 2003, perhaps this is a attempt to promote better turbulence in the chamber.

 

Here is a decent page explaining the mechanics of "squish" and detonation.

 

The mystery of detonation

[RichMaund]

I have seen that FBF is marketing higher compression pistons for the bike.

Much of what I see going on with tuners of these bikes makes me want to make a road trip this Spring to see todd Egan for a PCIII and some dyno tuning work personalized for my bike. Man! What a excuse for a road trip!

[Guest Buck]

There is a mouontain of science behind combustion chamber design, squish, piston shape, timing and fuel injection curves, etc., and they all have an effect on whether or not an engine pings.

 

Having said that the only way to accurately determine the cause of ping is to experiment with timing curves, fuel octane ratings, and injection mapping, assuming you are not interested in changing pistons or cylinder heads.

 

The Guzzi injection system is an antique. Not quite as bad as the BMW oilhead injection system, but in some ways not as good either. The biggest problem with the Guzzi (weber?) injection system is there is no feedback system to tell the computer how it's calculated injector pulse at a given moment is affecting mixture. In other words it's a guessing game. Even BMW used an oxygen sensor to tell the computer if the engine was running rich or lean so the computer could adjust accordingly for the subsequent injection events. Furthermore, neither the Guzzi or BMW systems have an airflow sensor or a map sensor to tell the computer the amount of air and/or velocity of air entering the engine. Instead they both use the throttle position sensor data and assume the throttle position sensor is set correctly. This is where the BMW system wins. At least it has an oxygen sensor so the computer can determine if it guessed correctly, or if the pulse duration of the injectors needs to be tweaked a little.

 

This does not make the injection system on the Guzzi bad. In fact it can be modified easier than many other systems because of it's lack of complexity. So, back to the pinging issue. When the throttle is opened abruptly, theoretically this is what is supposed to happen: The computer sees the change in throttle position voltage and uses that data in conjunction with engine rpm data to determine the new pulse duration for the injectors and ignition timing curve. Since the injectors are closer to the valves than the throttle bodies are theoretically the injectors should already be injecting the proper amount of fuel for the increased airflow when that increased airflow reaches the valves. Many injections systems have a momentary "accelerator pump" mode that they go into when the throttle is whacked open. This "accelerator pump" mode simply takes the place of an accelerator pump in an old carburetor. The computer will inject a couple of large squirts of fuel the moment throttle position sensor voltage goes high to make sure the mixture doesn't go lean from the sudden increased air flow. I don't know if the Guzzi injection system implements this feature or not. Regardless the cure most likely lies in the mapping. If an engine goes lean when the throttle is wacked open one of two things happens. If mixure goes too lean for combustion to occur the engine will stumble. If mixture goes somewhat lean (but not lean enough to be "un-burnable") pinging can occur. That is the event I would look at. The only way to really look at it is with a dyno and an exhaust gas analyzer, but you should be able to tweak mapping (with a power commander) to get rid of this problem.

 

Why didn't pinging occur on your previous CV carburetor equipped bikes? The answer is simple. In a CV carburetor the slide inside the carburetor is raised or lowered to allow more or less fuel into the engine. When you twist the throttle you are not moving that slide at all. The slide can only be moved by air flow. So as you open the throttle you are opening a butterfly in the carburetor that causes airflow to increase. This increased airflow acts on the slide diaphragm and causes the slide to open at a controlled rate. Fuel flow will increase proportionally with airflow. It's a self-balancing system, meaning fuel mixture stays within proper parameters because fuel flow is increased only as airflow is increased. There is no way to outrun or trick the system as could be done momentarily in a poorly mapped injection system.

 

In a standard flat-slide carburetor the slide is actuated directly (mechanically) with the throttle. The slide can be whacked open when air velocity is low, and it takes a moment for air velocity to increase and "suck" more fuel out of the main jet, so a stumble or hesitation occurs. Ok, it doesn't really "suck" the fuel out, atmospheric pressure pushes it out, but I'm trying to keep it simple. Anyway, many flat-slide carburetors have an accelerator pump that pumps an extra squirt of fuel when the throttle is twisted to try and keep mixture from going lean enough to cause any problems.

 

Until last year I was a master auto tech with 20 years experience. I was fortunate enough to come into the business when carburetors were still used widely, and I got to learn fuel injection theory and operation as it was becoming widely used in the industry. I consider myself lucky because I am not one of the "old dogs" who doesn't know anything about injection but can fix a carburetor blindfolded, and I am not one of the newbies who is scared to death of a carburetor. I'm both! Unfortunately I have a tendancy to get too complex in my explanations, so if some (or all) of this doesn't make sense and you want me to explain it again let me know.

 

Otherwise you might consider some remapping options if you are having moderate or large doses of pinging. If it is only momentary pinging it won't hurt anything.

[dlaing]

Great posts.

I'd just like to second the motion for remapping the system. If you are getting pinging, missing or rough running of the engine, and it is otherwise well tuned, then you should remap with the PCIII or the Ultimap. People don't always claim great power gains, but always claim better throttle response and driveability. If Guzzi put an O2 sensor on their bikes, there would be less need to remap, but since they did not, there is the advantage of one less fuzzy factor to mess up the equation. The trick is to get the equation right with a proper map, so that you do not need the feed back loop. Now, if Guzzi built a PCIII type "tuning link" compatible rom chip into every ECU and individually dyno'd the bikes out the door of the factory, you would have a lot more satisfied customers and cleaner emissions and less need for an oxygen sensor

[Janusz]

Just for the record I'd like to say that my bike not only NEVER pinged but it is impossible to make it ping even if you want to.

 

And yes, I am very familiar with what the pinging is on a variety of engines.

 

So how does it fit with the above theory?

 

I just think that if it is properly tuned as it should be then it will not ping.

[RichMaund]

Janusz

I'd say that the needs of your engine were very well fulfilled by the stock map. Other bikes less so to other degrees. You hit the Guzzi lottery Man!

Mine ran very well when new. Some tweaking by the Dealer's Tech after break-in improved driveability greatly. That eliminated a slight flat spot in the 4k range of rpm. The pinging on my bike is only momentary. Never really an issue for me.

 

The temptation though to see what is possible through the talents of a knowledgable tuner though is very strong!

 

Thank you all for your great inputs!

[Guest v11eric]

So,

Oure bikes are fitted whit very fast counting and very vast reacting computers, who get wrong or incorrect information from the sensors???

oure bike's have a oil temp sensor so when we drive a warm bike trough some water oure comp will richen the engine :finger:

 

confused

 

Eric

01 V11Lemans

[Guest mcloutier]

I can't comment on other peoples bikes but mine would ping under heavy load particularly on hot days. 100% cured by the installation of a power commander. Tuned it myself using my PC over about a week of short rides. I couldn't be happier with the results. The bike pulls harder throughout the RPM range and it never pings.

 

Michael Cloutier

Moses Lake, WA

02' Le Mans

[Guest Squashed Nose]

G'day,

 

I've had my '01 Le mans (registered '02) since April and I've learned more from reading this subject matter than I have since I bought it in April this year.

 

I test rode a '99 V11 sport and that suffered with 'pinging' as does mine. Yes, you can drive around the problem but I am always aware that it is there and it does detract from the riding pleasure. There is a lot of torque to be had at the bottom of the range but it cannot be accessed due to this infernal problem.

 

Can anybody supply some successful maps to put into a commander? It sure would save a lot of time.

 

Has anybody had the Termignoni cans and factory chip fitted and if so does this cure the problem as well?

[Guest Dirtybill]

I've owned my V11 for just a short time and I haven't noticed any pinging.

 

The fact that Januz and myself are not running with any of the pollution garbage on the bike is more than a coincidence that they both run fine.

 

I have no idea what this supposed flat spot is.

[dlaing]

Maybe you don't have the flat spot. To find out, try cruising along in 6th gear at about 3500rpms, give it a steady half throttle . If you have the flat spot, it should accellerate with a slight hesitation a little above 4000rpm with the power defiinetively kicking in about 5000rpm. If you get an aftermarket crossover, it will disappear. Some mufflers will also make it go bye-bye. Most bikes also have more vibratation around the flat spot. I find that tighter valve settings will increase the flat spot.

If you do not, lucky you!

[profWacko]

mcloutier,

 

Would you care to share your map with other PCIII users? I would like to try your pinging solution.

 

I was at the San Diego Rally and Todd Eagan made a composite map for me based on some of my observations of using 2 of the available maps from DynoJet. He also made a modification to the map that he had previously used on a different bike to kill off the pinging.

 

On my bike, this mod drastically reduced the pinging between 4500 and 5500 rpm, but the engine feels a little down on power in that range now, probably because it is way too rich there now. Overall, my bike runs really well with a really smooth power delivery, but feels a little flat in the range where it was pinging before.

 

I believe that this is because persuing this problem with the PCIII means that we are throwing fuel at a potential timing problem.

 

Any thoughts from anyone out there who really knows something about all of this?

 

Ride well. Ride safe.

-Jack Price

02 V11 Le Mans (nearly 31k miles now)

[jrt]

Enjoyed your post, Buck!

 

One other way to remap the injection system is to go the DIY approach:

 

http://www.jefferies-au.org/My16M/index.htm

(I saw that Cliff Jefferies posted this on MGCL this morning or yesterday).

 

An alternative to the PCIII, I suppose. I think it's a pretty cool idea, particularly when he implements the accelerator emulation and exhaust feedback. If you put in the effort to install and tune the computer, you should end up with an intimate knowledge of how the system works.

 

Cheers,

Jason

[Janusz]

That will not work since our computer is 15M not the old 16M. You cannot open and change 15M so readily.

 

The best way is PCIII.