First, I applaud your discipline in collecting the data and reporting it here.

I'd be concerned recording the relatively low mpg you experienced on your trip and will look forward to your next lengthy trip's mpg.

Also, why not set the afr at 14.4 or 14.6 at cruise settings? You won't hurt the motor and it will improve mpg.

Lastly, how can you adjust timing to be sure you're getting the most efficient fuel burn?

Nice data; look for more in the future.

Carl

 

With power vision and sure other tune devices you can set a max number I think its often about 8. But there is a table to that self adjusts all the time and will reduce as needed. I admit I am learning and dont undetstand it 100% but have the idea of it.

 

The knock retard is usually 2 tables. The first is the one you will see in the data. It is a "fast" knock retard that will pull up to 8 degrees. This is adjustable with some tuning devices and will remove more timing than is needed. The second is adaptive knock retard that will remove less timing but the value is retained between key cycles. Some devices have access to these tables and are kpa/rpm with values from 0 (lower kpa values) to 5 at at 100 kpa. The values are also adjustable with certain tuners. These values are slowly reduced back to zero if there is no more knock activity. The other thing that will happen if the ecm sees that the "fast" knock retard is not working is it will add fuel.

 

Let me try to answer some of your questions/concerns.

First let's discuss the mileage on my last trip. I've done several cross country trips over the last 10 years and my fuel mileage is always a bit lower out west. Here's what I think contributes to that. First, the speed limits are higher by 10 or 15 MPH. Generally 75-80 vs. the 65-70 back east. Next, there are areas of extreme heat out west that tax the **** out of the bike and also, the topography is much more extreme. There are many more altitude changes out west and going uphill is harder on mileage than the benefits of the downhill stretches. Finally the fuel formulations. 91 octane w/ethanol is the norm out here. Back east there is 93, even 94 octane available. So on my next trip, I'll expect the overall mileage to be a little better, but in some areas of the western portion of the trip I'll expect similar mileage to my recent trip.

I’m not sure which map I’ll have in the bike for the next trip but right now I’m leaning towards the 13.4 or 13.8 map. Unless I bring my laptop and can change the maps depending on the conditions I’m riding in as I cross the country, I doubt I’ll use the 14.2 map.

Now let's look at the AFRs. With AFRs in the 14s my bike pings so badly I’m afraid to ride it. Even with my timing retarded as I have now, during my current fuel economy test runs I was experiencing a very slight ping with the 14.2 map and that was at temperatures only in the 70s. I know those AFRs seem to work for many of you guys but they simply don’t work for me, my bike, and my riding conditions. If I could, I would. On my trip last year, a 9,000 miler with the 13.8 map, I had somewhat severe pinging in the desert southwest (temps 100 degrees +), yet absolutely not a single hint of pinging through the East and Midwest. That I believe is due to the conditions (as noted in the first paragraph) out west being so different than those farther east.

And finally, your question on ignition timing. My method for adjusting the timing was simply to start at the stock settings and remove one degree of timing advance at a time in the areas where I experienced the pinging. In effect, my timing is set just below the threshold where the pinging will occur. Without the ability to data track and analyze the anti-knock system on the bike, I don’t know of any better way to do it.

 

I am running a PCV tuner and my timing capabilities are limited to +/- changes to the existing factory timing curves. I have no monitoring or data tracking capability. If I ever get another bike, or another tuner for my current bike, I will make certain to get a tuner with this capability.

 

From a tuning standpoint, I think you're on the right track; i.e., bump timing until you experience pinging, then add fuel, and repeat for the variety of load and rpm's until adding fuel doesn't eliminate ping--then back off a couple of degrees of timing advance.

If your bike has trouble not pinging at 14+, even w/ retarded timing, I'd look for an intake or exhaust leak.

Carl

 

If I had an intake leak, I think I would see that in the AutoTune trims as it tried to compensate for the lean condition resulting from the leak. I have no abnormal trims so I can rule out an intake leak.

I also have no evidence of exhaust leaks. Aside from checking each joint at the time of assembly, there are no soot trails or any other indication of leaks.

I can understand the theory behind an intake leak contributing to a ping - excessive lean condition caused by the leak and the resulting higher combustion chamber temperature, but how would an exhaust leak contribute?

 

Running the PCV you are running open loop so your afr has to be set lower to allow for fuel quality. Stoich for 10% ethanol is 14.3 so if you are set around 14 you are close. If you were able to run in closed loop the o2 sensors will adjust for fuel quality.

 

Totally get the compensation element, but it is my understanding working with the WEGO Twin Scan that the O2 sensors are calibrated for gasoline, so even though the E blend has a different stoich value, it will still read 14.7 with the gasoline calibrated O2 sensors, when tuned to stoich for E10. You would need O2 sensors calibrated for E10 to get a 14.3 value when tuned to actual stoich. At 14, read by gasoline calibrated O2 sensors, there should be plenty of fudge factor for fuel quality variance.

 

That would be true running the PCV without an AutoTune or with the AutoTune disabled, but with the AutoTune enabled I'm running closed loop 100% of the time. The only exception is at 0% & 2% throttle positions where the AutoTune is effectively disabled by the zeroes in the target AFR tables.

And on a side note. Isn't it funny how these threads take on a life of their own? Not saying that's always a bad thing, just funny how it always seems to happen. The original intent of this thread was to simply highlight the effects that an AFR change has on fuel economy.