PC-V and Knock/Ping

[jcyuhn]

I recently installed a PC-V (without autotune) on my otherwise stock '06 FJR. I bought from FuelMoto and am using their map for the stock bike. While I like the smooth off-idle response and reduced vibrations, I am now getting very obvious knocking or pinging at low RPM and medium throttle. For example, when commuting in surface street traffic, I may slow to 2,000RPM in 4th gear while a vehicle in front of me makes a turn, the open the throttle to 50% without downshifting. I've had the bike since new and it has always handled this riding situation fine. Now with the PC-V in place it pings.

Pulling the map into the power commander software, I see that it reduces fuel at anything over 40% throttle, and the biggest reductions (-16) are at 2,000RPM and 60% throttle.

BTW, this map looks an awful lot like the wally smoothness map for the genII bikes. I haven't compared cell-by-cell, but just eyeballing it they appear to add or remove fuel in the same places on the map.

Anyone seeing any similar problems?

Thx,

- JimY

 

[ahchiu]

Your overloading the engine, 2k in 4th is too high, try 2nd or 3rd gear, your rpm needs to stay in the power band, between 3-5K.

 

[Chuck35]

Did you disconnect the O2 sensor?

 

[Fred W]

+1 to what the others have said, but I also understand what you are saying, that it used to be able to do it and now it pings. You are probably exactly right about those fuel cells leaning the mixture too far. Not many folks run the engines at 2k rpm and 40-50% throttle. I know that I never do, so what is in those cells of the fuel map is of no consequence to me, but I have noted they are large negative numbers.

A few ways to "fix" this: One way is to get a custom map made and request that they tune those cells. Most dyno's would be more concerned about high rpm, squeaking the most power out, so you'd have to give specific instructions to pay attention down there.

Another way, since you have a PCV would be to buy the auto-tune device and generate your own custom maps on the fly. That would be the best, but most expensive way.

The last way would be to just go into those cells and add fuel manually. It really won't affect performance much since you'll hardly ever be operating there, but you can just increase the numbers in the cells in a positive direction (less negative) that describe that operation a few numbers at a time until the knocking goes away. You might just want to enter zeroes in for all of those negatives, and that will just put the fueling back to the stock map there. This would be the cheapest option, but will require more fiddling around with a laptop and USB cable.

Good luck. Let us know what you opt for and how that works out for you.

 

[jcyuhn]

Thanks all for the responses.

I did disconnect the O2 sensor when installing the PC-V.

I have been thinking along the same lines as Fred. I may just tweak all the cells from 40% up to 100% throttle back to zero and run the stock fuel curve there. I've no complaints how the bike runs stock when caning it. Just looking for better off idle response, fewer vibes, and no surging at cruise.

It's not acceptable to me to limit use of the throttle based on engine RPM, gear, and other riding conditions. Page 5-3 of the 2006 FJR owners manual specifies the upshift speed from 3rd->4th gear as 25MPH. Based on the speed/gear/RPM excel sheet at fjr1300.info that would put the engine at about 1560RPM in 4th. It appears I am riding within Yamaha's recommended parameters for the FJR. I understand that you can avoid detonation by running a lower throttle opening at higher RPM. But come on, this bike has an engine large enough to power a compact automobile. It really ought to be able to pull around the 650lb FJR without complaint.

 

[RossKean]

I think the guy writing the shifting speed/gear was on drugs when he wrote it!!

 

[Fred W]

It's not acceptable to me to limit use of the throttle based on engine RPM, gear, and other riding conditions. Page 5-3 of the 2006 FJR owners manual specifies the upshift speed from 3rd->4th gear as 25MPH. Based on the speed/gear/RPM excel sheet at fjr1300.info that would put the engine at about 1560RPM in 4th. It appears I am riding within Yamaha's recommended parameters for the FJR. I understand that you can avoid detonation by running a lower throttle opening at higher RPM. But come on, this bike has an engine large enough to power a compact automobile. It really ought to be able to pull around the 650lb FJR without complaint.

Well... I certainly don't like the idea that your engine pings (detonation) under any foreseeable operating situation.

But, that doesn't mean that I will be adopting your practice of briskly accelerating from 2k rpm. That really does constitute "lugging" the engine, which is to be avoided for its long term health and longevity. I believe that you are doing your bike a disservice (even when it isn't pinging) by regularly doing that.

Yes, the 1300cc engine has a good amount of low rpm torque. Large displacement = big torque. But whacking the throttle open half way at rpms just above idle speed puts a heavy load on the engine.

Something to consider is that every engine is "tuned" for operating at a particular rpm band. Ignition advance and valve opening and overlap come into play regarding where that "sweet spot" will be on the engine. The ignition on the FJR does have some algorithms in the ECU mapping to advance and retard ignition, but the valve timing parameters are pretty much fixed, without any variable valve timing features.. IOW - They will be the same at idle as they are at redline. Therefore the engine will have a finite "band" that it operates well in. In order to get good sporty performance in the upper rpm ranges, the engineers have advanced the valve timing to such a degree that running at lower rpms is somewhat compromised. It's a good compromise for most of us.

This is not just a factor of the cylinder configuration either. Some folks think that all V twins are giant torque monsters that tap out at relatively low rpm, mostly because they see that kind of tuning from "The Motor Company" and other cruiser manufacturers. That is definitely not the case. For instance, my 2004 DL1000 Suzuki V-strom, whose engine was derived from the TL1000 sport bike, has a V-twin engine with a 9500 rpm redline, 500 rpm higher than the FJR's. FWIW, it dislikes heavy acceleration at low rpms ever bit as much, maybe more, than the FJR does. And, although this introduces a lot of more variables due to the desmo valve train, most Ducati V-twin engines have similar tuning targets, and even better high rpm performance. Also equally miserable low rpm lugging.

 

[Chuck35]

You need to be sure of the throttle % you have issue at.

When you see it on the screen in front of you during a ride, you will be amazed how far off your guestimate is.

You can ride with a laptop connected and carry a pilon to watch the laptop....or....

https://www.fjrforum.com/forum/index.php?showtopic=147612

I was supprised to see how little of the throttle I use during "normal" riding.

 

[Queensland Ken]

I was surprised to see how little of the throttle I use during "normal" riding.

I have the LCD 200 hooked up sometimes and can view live info and data log various parameters of the PC5.

It's really surprising how little throttle there is at 100kms hr, something like %7-%8, holding the speed steady.

One thing I learnt is that with the PC5, it is what the bike "thinks" is the throttle position and not the actual throttle position.

The PC5 must take it's info after the ECU and not off the TPS transducer.

Bought the LCD200 to prove to Mr Yamaha that the bike did have the high altitude surge fault with the ECU.

It wasn't a recall in Australia and has finally been replaced.

I would think an Autotune is the way to go and remove the PAIR air system, as per instructions.

 

[jcyuhn]

Chuck35 - Thanks, that is really cool! My wife works for a big evil phone company so we have lots of android devices around the house. I may have to try that.

I'm aware normal riding is all done at 10% or less throttle, it only takes about 10HP to move a bike down the road at 60MPH.

Lugging, uggh. That is a NEPRT worthy topic if ever there was one. I define lugging as running the engine at such low RPM that insufficient oil is supplied to maintain the bearing film and metal to metal contact ensues. It's easy enough to tell if this is occurring, an oil analysis will show the presence of bearing materials (lead and copper mostly). Hell, I even have some Blackstone labs sample containers in the garage and the FJR is about due for an oil change...

Googling around the 'net the more common definition of lugging is adding throttle but not getting any acceleration. That definately does not apply, the FJR accelerates very smartly from 2K RPM and with no bucking, hesitating, or unusual noises. Really don't see this as applicable. I tend to think Yamaha can build an engine that regularly delivers 50% of maximum torque without experiencing premature failure.

I've switched over to the Sprint ST for a while. Will follow up once I swap back to the FJR and update the PC map to let y'all know what it takes to correct the ping.

 

[Fred W]

"Lugging" an engine has absolutely nothing to do with oil pressure. Not sure where that idea came from.

It has to do with opening the throttle widely, at a relatively low rpm, which causes powerful combustion events to occur at a point where the piston hasn't fully cleared TDC (due to valve and ignition timing). This, in turn, puts energy shock impulses straight down the still relatively vertical connecting rod into the crankshaft. That energy has to be absorbed somewhere. It is absorbed in the crank, bearings and crankcases.

The valve and ignition timing is normally such that, even though the ignition spark may occur some predetermined time before Top Dead Center (TDC), the crank is rotating fast enough that the majority of the thrust from the burning and expanding fuel is (considerably) after TDC. The best possible point, if the fuel burned instantly, would be exactly when the crankshaft rod journal is at 90 degrees, since that is the point that the maximum amount of energy can be converted into rotational energy (torque).

YMMV

 

[ahchiu]

Googling around the 'net the more common definition of lugging is adding throttle but not getting any acceleration. That definately does not apply, the FJR accelerates very smartly from 2K RPM and with no bucking, hesitating, or unusual noises. Really don't see this as applicable. I tend to think Yamaha can build an engine that regularly delivers 50% of maximum torque without experiencing premature failure.

Yes, the FJR does accelerates from 2K nice but not in 4th gear.

 

[SoCalFJR1300]

I think the guy writing the shifting speed/gear was on drugs when he wrote it!!

They write it like that in every cycle manual I've read, not sure why.

In a car manual I would think they'd do that for maximum MPG but on a bike??

 

[dcarver]

Lugging can also lead to carbonized valves and other issues.

Don't ask me how I know..

This engine is made to run hard, IMHO.

Jestal had a great post on the benefits of full cylinder pressure and the desirable effects on the engine.

Too bad I don't remember them.

 

[jcyuhn]

Thanks Fred, that is the best explanation of what is going on that I have yet heard. Describing when the downward force of the piston & con rod is applied to the crank relative to its position allowed me to visualize how the force applied to the crank can be more downward vs. rotational depending on the timing of the combustion event. Never thought about it before, but I guess pinging represents even earlier combustion events, where perhaps the crank hasn't even reached TDC.

So let me ask a question, and I promise, I'm not just trying to be difficult here. I can see how in old tech engines that use a mechanical distributor or trigger points to start the ignition cycle that there would be significant compromises made regarding when the plug is fired relative to the crank position and that only limited, crude mechanical means to adjust the ignition timing were available. FWIW I am old enough to have played with distributor advance weights and springs back in my hotrodding days. On the FJR the ignition timing is controlled by the ECU software and presumably triggered based on a map that takes into account a number inputs such as engine RPM, throttle position, perhaps gear selection. If this were case, could not Yamaha's engineers trigger the spark at the optimum time relative to crank position and speed to avoid a lugging event as you've described above? Or are there other factors that constrain their freedom, such as the need to meet emissions regulations?

To SoCal - The FJR manual does mention those shift points as delivering the best fuel economy.

Dcarver - Don't worry about my bike, it gets plenty of decarboning exercise on a regular basis.

 

[Fred W]

It has to do with the fuel burn rate. The ignition timing is set based on an orderly ignition and burning of the fuel charge, starting at the spark plug and progressing as a "flame front" across the combustion chamber. This takes some time so that the peak pressure occurs well after the spark ignition.

Lower rpm allows increased contact time of the fuel charge with the hot combustion chamber parts, and opening the throttle up wide also increases the compression pressure, enough so that the fuel no longer burns progressively as intended. After the spark ignition, the pressure in the combustion chamber rises quickly, which instantly ignites the preheated fuel in somewhat randomly occurring explosions ahead of the flame front, in turn causing the peak pressure to occur too soon after ignition.

This does happen to a greater extent in a relatively leaner fuel mixture, which explains why you suddenly noticed pinging or knocking when you whacked the throttle open at low rpm with your new PC, which wasn't happening beforehand. The Yamaha engineers intentionally made that area of the fuel curve overly rich to minimize it, which is why we see the DynoJet corrections are big negatives in those areas, bringing it back to the stoichiometric fuel:air ratio target.

But even if those explosions were happening later, i.e. sometime after TDC, so that you weren't hearing any knocking, the impulses can still occur too soon for the relative crankshaft position mentioned earlier. Obviously when it is causing knocking that is far more detrimental to the engine's longevity. The sound alone clues us in on that. But a too early pressure peak after TDC is also not so great. You will certainly notice that your fuel mileage suffers if you run this way a lot as you won't be efficiently converting the fuel into engine torque.

You could also run a higher octane fuel, which would reduce susceptibility for this phenomenon, but most of us just keep the rpms up to ~3000-3500 minimum and the engine just sings along quite happily.