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Overview of EFI Options..XiED, Piggy-Back, Flash Tuners, Dyno ..

Overview of Popular EFI Tuning Options


Discussions on the different options of tuning an EFI Harley often times are very limited. Either due to passion, personal experience, etc., the entire spectrum of options is not explored objectively.

This is an overview of the variety of options available, so that people can make an informed decision, based on their needs, desires and budget.

This is by no means a complete list of all options, but it does encompass the 5 most popular ways that are currently being used in Stage 1 upgrades.

It also does not delve into a lot of the technical data (and there is a bunch), it is an overview so that one can choose which path, or paths, they want to explore more fully.

There are basically five ways to go in the tuning arena of a Stage 1:

1. Do nothing. Many advocate that no tuning change is needed at all when adding free flowing mufflers and intake. The ECM will make necessary adjustments. 

It is true that the ECM will make adjustments, and the bike will run. However, it will still be lean and probably even leaner than EPA requirements. It will run hotter, not accelerate as well, and may have hesitation in low speed situations.

There are many reports of people being very happy with this option.

This is the least expensive.


1.1 A dealer download (Stage I reflash) is an option.   A Stage I download does NOT alter fuel enough to matter, but it DOES alter it a bit. Timing is not touched, or in the few cases it is, again, it is not enough to matter, and the rev limit is increased.  EPA rules force HD, with that download to STILL mimic the EPA approved amount of pollution , etc.. and therefore, the engine is kept very lean.. similar to the stock calibration.  

It does not accomplish much and is as expensive as some piggy-back tuners that really can make a difference.

2. Use an XiED product. Many are very happy with the improvement in cooling, reduction in pinging, hesitation, and generally smoother and stronger acceleration.

This is an excellent option for a stock bike, a bike with free flowing air cleaner or exhaust, or a bike with both free flowing air cleaner and exhaust. It uses the base tune from Harley-Davidson, and adds some fuel into the areas that HD had to lean out for EPA reasons. The results are a much better running bike.

However, if you are looking for the best possible performance, it does leave 10%-15% of the available power on the table. It is a budget solution that many are happy with, because to get that extra 10%-15%, one needs to speed 400% to 900% or more money.

This is second least expensive and the most benefit for $ spent.

2.5 The Fuelpak is a piggy back device in a category by itself. It adjusts the AFR in both open & closed loop. It does not adjust the timing at all. V&H Customer Support will give you codes based on what mods you have done to your bike that change the tune. Many use the Fuelpak and are very happy with it. Others say their experience with it is very poor. Since this option does not allow any adjustment of timing this can be good for stock bikes up to Stage 1.

It is over twice the cost of option #2 and just a little less than option #3. The difference being with option #3 you can adjust timing (on most) and have complete control over the tune.

3. Use a "piggy-back" tuner like the PCV. These tuners can be used with a "canned" tune, or can be adjusted on a laptop computer or a Dyno. They override the Harley-Davidson tune and, if used properly, will deliver 100% of the available power.

Some do not like them because they sit on top of the HD ECM and in rare instances that can cause problems. However, in the right hands (a skilled person) they can give you a great tune, taking full advantage of all possible power.

This is the third least expensive and results can be great or poor, completely dependent on the quality and time put into the tune.

3.5 The FP4 is a "Flash" tuner in its' own category. It is not full featured, giving you control over every aspect like those in #4 below. However, it does give almost all control, and it is very easy to use. It connects to your smartphone via bluetooth for programming changes, updates and to display data from your bike (RPM, Gear, temp, etc.).

Because of the smartphone interface it is very popular. While it cannot be used with dyno tuning, it does come with an auto-tune feature.

This is about the same price as a piggy-back tuner, but more powerful, it is less powerful than a full featured flash tuner, but for Stage I bikes it will work 90% as well, and costs less.

4. Use a full featured "flash" tuner like the TTS, SESPT, or Power Vision in conjunction with a Dyno. These tuners can give you control over the ECM to get the best possible tune, delivering 100% of all available power. They do not override the HD tune, they actually change the tune in the ECM.

In the right (experienced & competent) hands, these will deliver the absolute best possible results. Unfortunately not only is this the most expensive route to go, there are 99 bad to mediocre people running dyno tunes for every truly competent person doing dyno tunes. The cost of the tuner ($500-$600) and another $300- $1000 in dyno costs make this the most expensive option, with the possibility of not getting any better results than one would get with a "canned" tune.

This is the most expensive and can deliver the best results, or poor results, dependent on the person running the dyno.

5. Use a TTS or Power Vision with Auto-Tune. This is the same "flash" tuner as option #4 above, but instead of spending $ on a Dyno tune, and possibly getting a poor tune due to the person doing the dyno uses the built-in computer to record how you ride, the conditions you ride in, and a variety of other factors, then the device makes changes accordingly, improving the tune every time you ride the bike.

This is a sure way to get 99%-100% of all the power available, and not have it rely on a person running the Dyno, that may or may not do a good job. It also will adjust for any future modifications done to the bike without incurring any additional costs.

This is the second most expensive option and reliably delivers great tunes every time.


We have used all of the above tuners.  (LINK to Tuners)

Our experience has shown:


The XiED Products are a very good way to get a stock, or Stage I, bike running smoother, stronger & cooler!  


The FP4 is a very good, almost Full-Featured, Flash Tuner.  It is a lot of fun to use, and it can deliver an almost perfect tune for Stock & Stage I bikes.


The Power Vision is the easiest to use of the Full Featured Flash Tuners.  While other tuners can deliver just as good of a tune as the Power Vision, they are much more difficult to use, and do not have the gauge features.  For these reasons we prefer the Power Vision.


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