What does this feature really do?What;s the difference between smart tune and auto tune?

 

On the SEPST (aka by some as SERT), autotune attempts to use the stock O2 sensors to calculate values for the VE (volumetric efficiency) tables of your engine. VE basically relates airflow to RPM and load. The ECM then uses the VE tables and other info to calculate the amount of fuel required at specific RPM and load to calculate injector pulse width (amount of fuel) for the desired AFR.

I think...

I think other tuners use wide band O2 sensors to more precisely dial in the values.

Not sure of the difference between autotune and smart tune

 

You are correct.

ThunderMax would be an example of this but as far as "more precise" most of the reviews I hear are mixed.

I believe AutoTune is the name of TTS VE correcting technology. Same as SmartTune.

 

To put it another way, this is what most people will use Auto or Smart Tune for...

To tune a bike you need something that measures performance i.e. a dyno. This measures the amount of power & torque being made at the different RPMs.

If you get this done yourself then the air-fuel ratios (AFRs) are adjusted (along with timing) at each RPM until you get best power and then the job is done.

However, if you rely on a map produced by someone else on a dyno (a canned map), then there will be variations between how well their engine flowed at each RPM and yours, due to differences in hardware and conditions. These differences are recorded in the VE tables, which record how well the engine flows at each RPM compared to the ideal figure for the engine. So the VE table tweaks the amount of fuel so that the desired AFR set in the AFR tables is what is achieved in the real world.

During an Auto Tune or Smart Tune session the bike is set with the AFR at the same value (usually 14.6) across all the AFR table. Then the actual AFR is measured and the two compared. Where the reading is leaner than 14.6 there is more flow than expected and the VE needs adjusting above 100% and so more fuel is added. The converse for a rich reading.

Once these VEs have been worked out then the normal AFR table is restored and its values will be more accurately reflected in the fuel applied.

 

From my understanding I can throw this in, stock O2 sensors with the help of a tuner such as- lets use powervision- will properly identify and be capable of analyzing data to 4200 rpm and possibly a bit more with the right tweaks. These are narrow band sensors and will efficiently adjust in closed loop (up to 4200 as mentioned.) If you buy wide band they will adjust/ analyze higher ranges considered open loop for people who often use wide open throttle such as raceing would need, but they won't do such great work down in the lower ranges. So if your not racing your bike on a track the stock O2's are just fine for most people. Plus if you have a good tuner like Jamie @ fuelmoto a map can be built which closely accomodates w o t .

 

Smart Tune and AutoTune are proprietary names for VE correcting tecnology used by SEPST and TTS respectively.

Closed loop means injector pulse width is controlled by the injectors. Open loop means that pulse width is a product of calculations based upon VE values, and data from engine sensors. SmartTune calibrates the VEs to more accurately represent the actual VE performance of your particular engine.

When in Smarttune mode a special map is uploaded to the ECM that among other things changes all the AFR cells to 14.7. This allows the narrow band (switching) O2 sensors to collect data across the entire AFR Range. Data will potentially be collected for every cell that is in closed loop (14.7). You are not limited to 4200 RPM.

SEPST stands for SCREAMING EAGLE PRO SUPER TUNER. It is designed for RACE TUNING engines.

 

Thanks for the replys guys.I recently had my bike tuned with a SEPRT and the tuner tech told me that he put the smart tune feature in use on my bike,he told that his bike was on the dyno and he put the smartune on his as well,I had alittle bit of popping right after I had the bike tuned but I have since been out on it and there doesn't seem to be any more popping,although I am getting a very nice deep rumble in the exhaust,so did the smartune tune out the popping?That was basis for my question to begin with.

 

You can do the same thing on the Dynojet Power Vision. It also tunes spark by auto-lowering spark advance based on the datalogs of knock sensors. They call it:

Log Tuner Basic - auto tune using stock O2s (limited to rpm range used by stock O2s)
Log Tuner Pro - auto tune using Wide Band O2s (entire rpm range)

 

He just used 4200 rpm as a typical stop point, where most tunes start heading into the rich zone and out of the range of the stock O2s. You are by no means limited to 4200 rpms, for tuning on a Powervision or otherwise, however, you are limited by the range of the stock O2 sensors. They can not sense **** when trying to do, let's say a WOT run with A/F ratios of 12.5 or less (example). They just can not sense anything that rich. They are only really good at very close to stoich 14.6-14.7. You need Wideband O2's for this type of tuning outside of this range.

 

Good info thanks man! I know with data logging raising the afr to 14.7 extends the range , which I think I said, but I wasn't aware it could carry all the way to open loop.

So I'm really not that far off the mark.
__________________