Why is tuning a bike so difficult ?
Ultimate HDF Member
Joined: Dec 2010
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From: wet coast BC
Even at HTT the AFV remains a mystery with best guesses from smart folk. adaptive fuel value. ECM adjusts fuel for temp, elevation & quality of fuel so is that AFV.
Then is there another AFV that tries to adjust fuel back closer to stoich, this being the one that we re flash the tuner for when it does not feel right.
Then is there another AFV that tries to adjust fuel back closer to stoich, this being the one that we re flash the tuner for when it does not feel right.
Extreme HDF Member
Joined: Nov 2007
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From: East of the Sun, West of the Moon
IMO, the OP's initial question about tuning difficulty:
- HD Shops - you bring your bike to a shop that is not experienced enough to tune with a SE let-alone anything else. Remember most of these guys are parts changers and Harley Bible readers and can't or won't think outside the box. Of all the HD shops out there today I would venture to say that probably 75% (if not more) when they get a big build or a special build, they bring in an outside tuner as a contractor to do the tune work for them and the bike owner is usually none the wiser. Do your homework on tuners. Find a reputable tuner (usually an indy) and find out what they prefer to tune with and go with that device.
- Home Tuning - for the "end user" tuners, it usually boils down to the simple fact that I myself have done in trying to tune a bike page by page. This is not the way to tune your bike. It can be done but will take you a tremendous amount of time mainly because on page 2 there is a lot of setup information for your initial tune that directly correlates to page 185 and if you read up to page 2 only, setup a tune session, go tune, then come back and realize something is wrong; you'll then find your answer on page 185. These page numbers are simply examples by the way. Read the manual twice.. Then when you're done reading the manual ask questions. Then you go tune..
Ultimate HDF Member
Joined: Dec 2010
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From: wet coast BC
This is where it gets confusing. Without O2 sensors, you lose the adaptive fueling. In open-loop, you're not using the O2 sensors for feedback, so you're only getting AFVs in whatever area(s) you're running closed-loop. In closed-loop, the ECM looks at the target Lambda versus what Lambda the O2 sensors are reading, then makes what adjustments it can. The ECM then extrapolates that data and applies it to the open-loop areas as well, BUT there's no feedback there, so you're relying on the VE table being correct in the first place AND that the AFV changes in the closed-loop part of the map are applicable to the open-loop sections.
This is why I keep telling people that tuners that disable or disconnect the O2 sensors are not a good solution, and that the key to having a bike run the way it should is making damn sure the VEs are exactly where they should be. This allows the AFVs to do nothing more than compensate for atmospheric conditions, fuel quality, and your air filter getting dirty (yes, that really does make a difference).
This is why I keep telling people that tuners that disable or disconnect the O2 sensors are not a good solution, and that the key to having a bike run the way it should is making damn sure the VEs are exactly where they should be. This allows the AFVs to do nothing more than compensate for atmospheric conditions, fuel quality, and your air filter getting dirty (yes, that really does make a difference).
Ultimate HDF Member
Joined: May 2008
Posts: 7,439
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From: 'Noke, VA
Even at HTT the AFV remains a mystery with best guesses from smart folk. adaptive fuel value. ECM adjusts fuel for temp, elevation & quality of fuel so is that AFV.
Then is there another AFV that tries to adjust fuel back closer to stoich, this being the one that we re flash the tuner for when it does not feel right.
Then is there another AFV that tries to adjust fuel back closer to stoich, this being the one that we re flash the tuner for when it does not feel right.
5% correction is the number I've seen or heard from many sources. I would have sworn it was in the TTS tuning guide, but I may be wrong.
IMO, the OP's initial question about tuning difficulty:
- HD Shops - you bring your bike to a shop that is not experienced enough to tune with a SE let-alone anything else. Remember most of these guys are parts changers and Harley Bible readers and can't or won't think outside the box. Of all the HD shops out there today I would venture to say that probably 75% (if not more) when they get a big build or a special build, they bring in an outside tuner as a contractor to do the tune work for them and the bike owner is usually none the wiser. Do your homework on tuners. Find a reputable tuner (usually an indy) and find out what they prefer to tune with and go with that device.
- Home Tuning - for the "end user" tuners, it usually boils down to the simple fact that I myself have done in trying to tune a bike page by page. This is not the way to tune your bike. It can be done but will take you a tremendous amount of time mainly because on page 2 there is a lot of setup information for your initial tune that directly correlates to page 185 and if you read up to page 2 only, setup a tune session, go tune, then come back and realize something is wrong; you'll then find your answer on page 185. These page numbers are simply examples by the way. Read the manual twice.. Then when you're done reading the manual ask questions. Then you go tune..
Tuning a parts combination from scratch is doable, but it's a long, painstaking process. I'd go for the pro tune on that, as long as I had someone that I trusted to do the tune (I do).
Ultimate HDF Member
Joined: Dec 2010
Posts: 7,776
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From: wet coast BC
[quote='05Train;11611518] AFV is strictly making changes to the VE's by comparing the target Lambda to what the O2 sensors are reading.
quote]
HIHO HIHO its off to work I go.
I have to disagree on the above as it has been agreed that the ECM does not know the amount of air entering and uses the VE as the fixed air volume then adjusts the fuel to achieve the AFR requested
quote]
HIHO HIHO its off to work I go.
I have to disagree on the above as it has been agreed that the ECM does not know the amount of air entering and uses the VE as the fixed air volume then adjusts the fuel to achieve the AFR requested
Ultimate HDF Member
Joined: May 2008
Posts: 7,439
Likes: 884
From: 'Noke, VA
I have to disagree on the above as it has been agreed that the ECM does not know the amount of air entering and uses the VE as the fixed air volume then adjusts the fuel to achieve the AFR requested
The only way incoming airflow could be measured would be through a mass air meter and a completely different type of fuel injection.
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
However there is something being missed here. Autotune can only tune within pre-programmed parameters, set by the manufacturer of the tuner. In addition there is no feedback loop, that is to say that auto-tuning does not give sight of the actual performance of the engine, or compensate for any glitches.
The only way that can be done, that is readily available to us, is a dyno. The benefit of tuning on a dyno is that the engine performance is optimised for torque, as well as air/fuel ratio. Some engines may have a flat-spot that can be tuned out or improved by altering air/fuel or ignition timing, which no autotune is going to be able to do.
So to ultraclassic53, an auto-tune doesn't require any skill, except to operate a computer, while a dyno tune requires a skilled and experienced operator. That is why some dyno shops have a great reputation and attract a lot of customers.
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Road Captain
Joined: Jul 2012
Posts: 633
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From: missouri
Do the tuners themselves actually every go bad themselves? And when I use the use the term tuner I mean the the SE pro tuner itself , not the guy running the dyno who goes on a month long drunk over a blond with big ones ...
Extreme HDF Member
Joined: Nov 2007
Posts: 14,670
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From: East of the Sun, West of the Moon
i had a PV that the display went completely black on. Still worked and did what it was supposed to do via the computer and ECM interface but no display. DJ swapped it out no questions asked.
I had a TTS (original TTS) that would no longer communicate with the ECM. Steve swapped it out for a newer model no questions asked.
My SE units have never gone bad but then again, they've always been stored away as I won't use them. They all came with bikes I purchased.
I had a TTS (original TTS) that would no longer communicate with the ECM. Steve swapped it out for a newer model no questions asked.
My SE units have never gone bad but then again, they've always been stored away as I won't use them. They all came with bikes I purchased.