Other way around. You get your desired closed loop afr set and then auto tune/ vtune or whatever your tuner calls it, and the software will adjust ve based upon the recorded results. The more cells hit with the broadest range of rpm/map/tps will yield the best ve change. It can almost become an overcoming challenge to do when removing knock with timing changes, decel pop if had, accell enrichment if sluggish off line, egr tables, etc,etc. This is why its so hard to find great dyno operators. You can't do all this and get bike in/out for 2-3 hours work. Need 5 hours at least to get good dyno tune. A lot of places won't put the time in. I got 10 hours in mine vtuning and not close to perfect. Get decent milage and performance but a lot left to gain with more time.

 

Thanks!!

 

The first part of your post is technically correct. One should make changes to the VE's which will, in turn, affect the AFR.

Unfortunately, without an accurate wide band external sniffer and a good dyno machine (both should be calibrated for each use), one could spend months trying to accomplish essentially the same thing by just properly setting the VE's to begin with. And setting the VE's to that magical 5% mark shouldn't take more then a couple hours. Once the VE's are set, it's simply a matter of setting the AFR to whatever number that works for that application.

Hope that makes sense...

 

Yes, but...

No surprise, it's very difficult (ok...impossible) to get consensus on the internet.

What's far more common is to get as many opinions as there are posts. Your reply does make sense. I'm going to re-read the documentation I found online, and make sure I understand the normal order of operations. My local tech did tell me you work through the VE tables first. Luckily, I have now found a guy who is DynoJet certified, so I have another source. And, I'm getting a baseline run tomorrow, so that's another person to talk to.

Hopefully, a common thread will begin to emerge...

 

hi,

how is VE set? what sensors are used and are the vtune, autotune or whatever else calculations accurate enough?

great topic

thanks
mirrmu

 

Yes, get the VE's set first assuming you have the correct cam settings (IVO at least).

Both the TTS and PV have programs that help get this done. I use the TTS system and have found it to be accurate (again, assuming one sets the IVO and a couple other constraints properly).

 

When I tuned my sportster mt7 cal I was told and read that any clb change after 1st vtune would require starting over again. So if after 4 vtune changes I decide to go 750 from 700 then next vtune shouldn't generate from previous runs that used 750. So that change in closed loop Afr would throw all ve out if whack if continued to generate from prior clb vtune runs. So in layman terms the Afr closed loop had to be set right before the ve was recalculated. Assume lambda closed loop would be same.

 

Ok I have Smart Tuned the bike and now the VE Tables are reading closer. Bikes runs great. I had a decel pop about 2,000 rpm either with a quick let off or sometimes with a slow decel of the throttle. I had my decel enleanment set to about .50 so I raised it to over 1.00 and now the decel pop on slow roll out of throttle is gone, but still have a slight pop on quick let off of throttle at 2,000 rpm. As either in 2nd or 3rd gear. The bike has had that pop since new as I stated previously. Should I just leave it or can I get rid of it. I have read when you change front pipes and mufflers will have a slight decel pop. My friend has a 2010 Ultra with Stage 2 and V&H Monster Rounds and seems to have no decel pop.

 

If the pop occurs within a second or two window of quickly letting off the throttle, the decel enleanment MAY help. I say may because an exhaust leak can cause the pop.

One really needs to find out where in the map (both rpm and kPa) the pop happens and then adjust from there. In some cases a decrease in fuel may help whereas an increase in fuel will not.

FWIW, some systems are just prone to popping regardless of the amount of fuel added or removed. But I have seen some guys add so much fuel that the bike begins to have other, more serious, issues.

 

Yes, the AFR had to be set to the closed loop switching number if one was not using an external sniffer. Again, the switching number is nothing more a point in which the system begins to use data from the onboard O2 sensors that will eventually help properly set the AFR numbers.

Lambda calibrations no longer use the closed loop bias table. So, one more thing we don't need to think about.

Those calibrations that do use the CLB table can negatively affect the VE's if it's changed mid-stream. Again, some cells not so much and other a bit more. Yes, it helps to keep the CLB constant just as using the same gas through the entire tuning session as well as trying to keep environmental conditions to same too.

Just remember that the larger the CLB number, the more quickly the O2 sensors will degrade. And if you look at the difference in AFR's for even moderate CLB changes, the motor doesn't really get that much out of the change.

For me, when tuning with those calibrations that use the CLB table, I rarely used a setting more then about 645 because the AFR difference between 645 and say 775 is less the 2/10's of one point AFR.