Your (Hopefully) One-stop Resource for EFI Management of Harley-Davidsons - Harley Davidson Forums: Harley Davidson Motorcycle Forum
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post #1 of 42 (permalink) Old 01-22-2009, 11:23 PM Thread Starter
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Your (Hopefully) One-stop Resource for EFI Management of Harley-Davidsons


Ever since I bought my first motorcycle, a 2009 Harley-Davidson XL1200N, I have spent way too much time searching, and searching, and searching through the thousands of forum articles regarding Harley-Davidson EFI management. I have tons of issues with the “lean condition” of new Harley-Davidson motorcycles, including sputtering, pinging, popping on deceleration, and more. I decided at work, when I didn’t want to do work, that nobody else should have to search aimlessly for the [mostly] right answers to these ultra-common and oft-repeated questions. I decided, nobody should have to stress-out about their motorcycle’s EFI system for more than three mouse clicks. So, here you go.

Important: if I missed a question, be sure to respond with (1) the missing question and (2) your best answer. If you disagree with my answer to one of the below questions, respond with (1) the full question and (2) the reason you disagree and your answer.

Note: the answers to these questions include my opinions, not necessarily a “fact”.

Q1: What is EFI? What is EFI vs. a Carburetor?
EFI = Electronic Fuel Injection. All you really need to know about it is that a computer actively controls the amount of fuel that enters your engine based upon a pre-programmed set of ‘if, then’ commands, generally called a “Fuel Table” or “EFI Table”. For example, “if the engine is cold, then run the bike with a rich fuel mixture for five minutes.” EFI is a good thing.
There are three main differences between an EFI and a Carburetor: (1) again, EFI is an active fuel management system that is computer controlled, and often, but not necessarily, uses oxygen sensors to facilitate the management of your fuel mixture. A carb. is not computer controlled, at least not on a motorcycle, and is a far older technology. Since this isn’t an article about carburetors, just understand that they passively inject fuel into your engine. This is why you need to “pull the choke” when first starting your bike, for example. (2) You “adjust” your EFI by reprogramming computer software. This is often made ridiculously expensive, but gives “the brains” (engineers) the advantage over “the brawns” (mechanics), so to speak. You adjust a carb. by physically changing certain parts of the unit itself. (3) EFIs give you infinitely more options to adjust your air/fuel mix, but also allow much less “wiggle room”. There are some other major differences, but we’re keeping it to what you really need to know here.

Q2: Is my EFI-equipped Harley too lean from the factory? If so, why?
The answer is simple: Yes. Why? Because the EPA continues to raise the engine efficiency standards required for new vehicles. In other words, your brand new Harley has to put out a lot less “Greenpeace-pisser-offers” then your ’71 Shovel did. In order for H-D to use the air-cooled, V-twin that makes that signature H-D sound (frankly, relative to H-D’s Revolution engines and others out there, a dated technology), they have to lean-out the fuel mixture in order to meet these standards and sell bikes.

Q3: If I just install new pipes, do I really need an EFI flash or tuner?
Despite what the debate seems to suggest on the forums all over the internet, the answer to this question isn’t hard. Do you NEED to reprogram your EFI? No. Should you, YES! Your bike comes almost dangerously lean from the factory. Freeing up the engines airflow with less restrictive pipes is functionally going to make it run leaner, which, as you’ll read below, is bad. Suck it up, and get yourself a tuner to richen up the mixture and, if possible, manage the timing. Back in the “carbed days”, a minor set if new slip-on pipes didn’t require any work. In these EFI days, 95% of the time, you’re due for at least a $150 ECU reflash – if you can get a dealer to do it.

Q4: What does it mean to “flash” the EFI system?
Flash = reprogram the existing ECU unit with a new set of injection commands. If you’re computer savvy, it’s sort of like flashing the BIOS. If you’re not computer savy, it’s exactly like replacing what was there with something new. Usually these “flashes” are something like $150 and preprogrammed by folks somewhere. You’ll read below what options you have to manage your EFI system, but note that some “race tuners” don’t actually “flash” the ECU, they trick it into doing something advantageous to your air/fuel mixture as directed.

Q5: What’s the difference between an EFI and an ECU?
Nothing, really. I mean, there is but they’re all part of the same system. The EFI is the fuel injection system. So that includes injectors hooked up by wires ultimately to the ECU which is often hooked up to a “race tuner” and/or O2 sensors. If you haven’t figured it out already, the ECU is the computer. God knows what ECU actually stands for, but I’m going to guess: Electronic Computer Unit or Extra Change User.
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post #2 of 42 (permalink) Old 01-22-2009, 11:23 PM Thread Starter
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Q6: How do I know my bike is running lean? Running rich?
If your engine is “too lean”, your spark plugs will be white at the tip. Your exhaust will also tend to “pop” when you let off the gas or decelerate and your engine will sound hollow or “starved”. If your engine is “too rich”, your spark plugs will be black at the tip, your engine sound will sound muddled, and you’re exhaust smoke will look like a drag racing diesel truck’s. If your engine is just right for it’s set-up, your spark plugs’ tips will be sort of tan, your bike will “feel right”, your power band will be even (or even-ish), and the sound of your engine will be robust. If your baby is black, and you’re white… you’re in the wrong forum.

Q7: What does “lean” mean? What does “rich” mean? Which one is better?
Lean = more air, less gas. Rich = more gas, less air. Neither is better than the other, and both can harm the engine at their extremes. The leaner your air/fuel mix gets, the hotter your engine will get; the harder it will be for the engine’s internal combustion to happen because of a lack of fuel (not air); and the more heat damage you could do to the insides of your engine. The richer your air/fuel mix gets, the cooler your engine will run (to a certain degree); opposite of a lean condition, the harder it will be for the engine’s internal combustion to happen because of a lack of air (not fuel); and the more carbon gunk and oil damage you could do to the insides of your engine.

Q8: What are my EFI management options (i.e., flashes, tuners, new ECUs)?
Simple “flashes” $
They are the cheapest, easiest way to change your air/fuel mix. H-D provides them. They’re like a Super Nintendo cartridge that you plug into your ECU and it automatically “flashes” it with the new data. H-D often has a “flash” for common Screamin’ Eagle parts set-ups, which can often work good-enough for similar set-ups. Most dealers, in my experience, won’t do a flash for you – some will even say it’s not possible (a lie to get you to buy something more expensive). But, you can literally go on and order one specifically for your bike’s setup… or something close to it. Still, the dealers are sort of right, a flash isn’t the greatest option because they don’t allow you to do an Dyno tuning… and no two V-twin engines runs the same.

“Race tuners” $$
Common options are: H-D’s SERT (or even the SERF), the PowerCommander (III and V), the Vance & Hines Fuel Pack, TTS MasterTune, TFI Techlusion, and some others that I never hear much about. These are piggy-back units that connect to your ECU and trick it into doing things you want it to do. They work well, they sometimes circumvent the need for a Dyno run, but also allow you to custom tune your EFI system with a Dyno run, if you so choose (or need).

ECU Replacements $$$
This is my favorite option. It’s also generally the most expensive option, too. You literally take out your factory (Delphi, generally) ECU and replace it with the new one. The options I know about for most H-Ds are the ThunderMax EFI (my favorite) or the Daytona Twin-Tec. Both are very good, and are better ECU units with more features (in many happy customers opinions) than the stock ECU. By default, they pretty much will always operate faster than a stock ECU with a tuner attached to it. The best, best, best part of these ECUs is that they have a feature that will auto-tune your air/fuel mix actively to achieve certain air/fuel mix and/or timing parameters you program into it at all times. No race tuner can do that, to my knowledge. also has XIEDs, which do sort of what a race tuner does and tricks the ECU into essentially richening the fuel mixture. Apparently they work for some, but they didn’t do anything (good or bad) on my bike. Some folks say they’re great for lowering the engine temp on a stock bike (by richening the air/fuel mix). My experience with them is limited to a 1200cc EVO engine. If you like XIEDs, tell us why and prove it.

Q9: What flash should I get? What settings should I input on my tuner or new ECU?
If there is a flash or a pre-programmed option for your exact set-up on your bike, you should be safe with choosing the appropriate option (the flash programming, or in your race tuner’s or replacement ECU’s settings). If you have a set-up that nobody’s previously made a flash or EFI table for, then you’re best off sucking it up and dropping the cash for a proper Dyno tune. Independent Dyno shops (i.e., not H-D dealerships) are often better and more economical than an H-D dealership. Honestly, because even the same two engines run a bit differently, you’re best off getting a Dyno tune every time – unless you bought yourself the ThunderMax or Daytona Twin-Tec EFI with the auto-tune feature. In their case, you just get close to the idea EFI map, and it’ll tweak the curves over time. You can, of course, manually tweak things in replacement EFIs and have your bike Dyno tuned to perfection. Ain’t no thang!

Q10: What’s the best exhaust and/or air cleaner upgrade?
Quick answer: the one you like. I’m not going to answer this in much detail because this is an EFI article. But, quickly, if you want speed and power, get an air cleaner that sucks in a ton of cool air and a 2:1 exhaust. If you want noise and don’t care about power, get straight pipes and a standard high-flow K&N filter. Both qualify as the Stage 1 upgrade. If you want everything – noise and power and this and that – then get yourself to numerous H-D events with LOTS of bikes and start asking those guys for advice.

Q11: Could EFI be responsible for my bike being jerky compared to my old carbed bike?
Yes! Oh yes. EFIs are faster and more “accurate”, meaning they’ll react faster and more noticeably to even the slightest twist of the handle. This happens with newer bikes, especially ones with stiff suspensions. You’ll learn to compensate for it, and your bike will “loosen up” a bit after 1,000 miles. Relax. I also recommend getting larger diameter handles… which allow you to more accurately control the throttle. My Nightster was super jerky when I got it, then I got larger handles and gave it some breaking-in time and it eventually was perfect: crisp but not choppy.

Q12: Will my girlfriend/wife or boyfriend/husband leave me if I buy an H-D?
Let me answer this with a question. Do you care?

Disclaimer: I do process improvements for a living and, thus, I am not an EFI expert, nor am I a mechanic of any kind. It was not an easy process to get the information I needed regarding EFI, so I decided to make a process improvement where it was greatly needed. I’m not liable if your bike malfunctions as a result of the advice in this post – whether that advice be from me directly or a forum poster. I’ve simply consolidated knowledge (whether correct or not) learned from various forums across the web and my prodding into the thick skulls of the enlightening individuals that work at various dealerships. Also, this is not intended to be a technical write-up. I’m more likely to understand women instantly than understand graphs and charts produced by a Dyno or tuner.
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post #3 of 42 (permalink) Old 03-19-2009, 09:18 PM
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I have a 2005 Roadking Classic Rinehart true duals with a high flow air cleaner have had the remap still sucks so am thinking of the Thundermax what do you think?
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post #4 of 42 (permalink) Old 03-31-2009, 06:33 PM
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I have been browsing the forum and trying to understand all the technical talk, with little luck. This post as been very infomative, many thanks.
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post #5 of 42 (permalink) Old 03-31-2009, 10:28 PM
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I have a iron 883 and just purchased a set of hooker troublemakers for it, any recommendations as to whether i need to have harley do a flash, get something aftermarket, or leave it alone?? any help appreciated.
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post #6 of 42 (permalink) Old 04-11-2009, 01:40 AM
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post #7 of 42 (permalink) Old 04-19-2009, 05:55 PM
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Boom - great collection of info on tuning and the role EFI plays...

BlackIce - the answer is no. SERTs are married to the first bike they're keyed to... sorry.
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post #8 of 42 (permalink) Old 04-19-2009, 07:34 PM
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I now have a ThunderMax EFI w/auto tune in place of my Delphi. So far so good. I put it on yesterday and put about 200 miles on my bike today. It idles much smoother, uses about the same ammount of fuel and starts as soon as I touch the starter switch.
Now I just need to figure out how to adjust the AFR and lower the idle a bit.

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post #9 of 42 (permalink) Old 04-22-2009, 09:31 AM
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I install a new Power Commander V with Autotune on my 07 Street Glide which I was having tuning issues with because of buying the bike used and not knowing that the cams have been changed out for sc255's. After a few rides and letting the autotune do it's thing the bike ran perfect even though the original map was not right for those cams. My fuel mileage is also over 40 mpg us, about a 20 to 25% increase. GREAT PRODUCT
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post #10 of 42 (permalink) Old 04-26-2009, 12:48 AM
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Originally Posted by 09BLACKICE View Post
No. The race tuner "marries" itself to your ECU. If I'm not mistaken you can use it for diagnostics on another bike of like nomenclature,but cannot use it to make any adjustments to anyother than the bike it was initialy married to.
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