Mark Vernact's Accelerator Module.

Discussion in 'Parallel Universe' started by KnuckC, Nov 14, 2010.

  1. KnuckC

    KnuckC F8er

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    Just installed Mark Vernact's "Accelerator" module. It has to be the simplest mod for this bike and IMO it works. I installed the compact version. There is also an extended version that will allow you to mount an IAT sensor anywhere on the bike.

    Mark has a detailed description of how the module works on his website. The simple explanation is that it fools the ECU computer into thinking the temperature is cooler than it really is resulting in a richer fuel mixture. If the mixture is too lean you may get slight lag which results in a snatchy throttle response. By changing the mapping to eliminate too lean a mixture, it smooths out the throttle response throughout the entire range. This is especially useful in first gear on technical terrain.

    I am not yet convinced that it provides a noticeable difference in acceleration, although theoretically without lag it should, but I am convinced that is does provide smoother throttle response which IMO makes it well worth the cost. I don't know why after three years BMW has not chosen to incorporate this fix into the standard mapping. Maybe there is a software update that I am not aware of.

    I have not had an opportunity to test the module in hot weather. I would be interested to hear feedback as to how the module performs under extreme heat and if there are any issues.
    #1
  2. Firefight911

    Firefight911 Been here awhile

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    Be careful when enrichening the mixture. You will have an increase in exhaust temps through the catalytic converter. Depending on how rich the mix has become it could spell death to the cat and/or less or more damage.

    As to why it hasn't been incorporated, that's easy, it won't pass emissions rules.
    #2
  3. The Griz

    The Griz Long timer

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    This is the alternative to the Booster Plug. Basically tries to achieve the same thing: richen the air/fuel ratio a few percent throughout the RPM range.

    http://www.boosterplug.com/?menu=1

    Richening a gasoline engine's air/fuel mixture DOES NOT make it and the attached exhaust system run hotter. It is in fact the other way around. A richer engine runs cooler, and will also make the attached exhaust system including catalytic converter run cooler.


    #3
  4. raider

    raider Big red dog

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    Indeed. This is why light aircraft pilots respond to rising CHT readings by richening the mixture. And why Bonneville Flats-type speedsters want to lean it out.

    The quote you post, explaining the increased prevalence of CO (vs CO2) in rich exhaust gas is why EPA regs demand lean mixtures - leaner than would otherwise be ideal.
    #4
  5. Camel ADV

    Camel ADV Long timer

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    As mentioned earlier, more fuel in a gasoline engine = cooler temp. A diesel engine is opposite.
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  6. jscottyk

    jscottyk Been here awhile

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    Just to add to the collective clarification, the more fuel in the fuel/air mix hitting the top of this piston, the cooler the combustion chamber will run. Going too lean will lead to excessive temps on the top of the piston and it's rings. This eventually leads to the lean seize in two-stroke engines.
    #6
  7. Firefight911

    Firefight911 Been here awhile

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    I agree with you as it relates to the engine but, as my posts states, I am referring to the catalytic converter not the engine.
    #7
  8. raider

    raider Big red dog

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    Reading into it a little, that sounds right. The cat converts carbon monoxide to carbon dioxide in an exothermic reaction (creates heat). More carbon monoxide - as produced by a richer engine - creates more reaction, and hence more heat, potentially causing the cat to melt, or at least overheat. Depends on how massive a change this module makes to the ratio though - to be effective, it would only need to be small, and you'd need a BIG change in ratio to cook your cat.
    #8
  9. The Griz

    The Griz Long timer

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    Oh I see what you guys are talking about. Unfortunately 1bmwfan, and I agree with raider here, that the amount of carbon monoxide needed to actually overheat the cat converter is not too possible with this bike. You'd need a fuel mixture so rich that the bike would barely run. And if you hypothetically could keep it running, you'd have to run it for a long time to see any ill effect on the cat.

    Worrying about a 6% richer mix doing damage to the cat on this bike is pointless. It's not going to happen, and is worth moving on from......

    These bike are tuned so damn lean from the factory in the first place. Richening the mix a mere 6% while using an aftermarket air filter and aftermarket exhaust is simply getting the AFR back into the range it should be, due to the fact that the aftermarket exhaust and air filter leaned it out further than stock form.
    #9
  10. LukasM

    LukasM Long timer

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    Griz my friend,

    I remember having a funny discussion with you about this exact topic, you know, the one where you were just targeting 14.7:1 as the "perfect mixture". :D

    Apparently you have some new information that the bikes run even leaner than that, care to share the A/F graph or other source of info?
    #10
  11. The Griz

    The Griz Long timer

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    Lukas my friend,

    I too remember having a heated conversation with you regarding Air Fuel Ratio, and how you completely read wrongly into what I was saying. So let's not got here again.:nah

    I don't see where I said I have any new information regarding the mixture of the F8. Rather, it is common knowledge that modern fuel injected motorbikes are tuned to run as lean as possible in stock form from the factory, in order to conform to EPA and Euro emission specs. So when you add a higher flowing air filter like a Uni and a higher flowing aftermarket exhaust, the bike will go even leaner. Yes, I know these bikes' computers have a 'learning' mode and will try to 'adjust' for the new additions, but it doesn't do as good of a job as it could. I can attest to it, I'm running a Uni air filter and a Leo Vince Carbon exhaust. It's too lean. Pop pop pop, surge surge surge.

    I still stand by 14.7:1 as being the 'perfect' air/fuel mixture for a gasoline engine. However, that 'perfect' ratio is not achievable given the fuels we have available to us today, especially the oxygenated ones (10% ethanol). C'mon Lukas. I'm not making this shit up. It's fact and common knowledge. If you still don't want to come to terms with scientific fact about the 14.7:1 stoichiometric ratio, you'll have to deal with it on your own. And we all (including me) have and do know that most gasoline engines are tuned with a 14:1 or 13.5:1 AFR so that they can cope with differences in fuels and atmospheric conditions.

    http://en.wikipedia.org/wiki/Air-fuel_ratio

    A mixture is the working point that modern engine management systems employing fuel injection attempt to achieve in light load cruise situations. For gasoline fuel, the stoichiometric air/fuel mixture is approximately 14.7; i.e. the approximate mass of air is 14.7 mass of fuel. Any mixture less than 14.7 to 1 is considered to be a rich mixture, any more than 14.7 to 1 is a lean mixture - given perfect (ideal) "test" fuel (gasoline consisting of solely n-heptane and iso-octane). In reality, most fuels consist of a combination of heptane, octane, a handful of other alkanes, plus additives including detergents, and possibly oxygenators such as MTBE (methyl tert-butyl ether) or ethanol/methanol. These compounds all alter the stoichiometric ratio, with most of the additives pushing the ratio downward (oxygenators bring extra oxygen to the combustion event in liquid form that is released at time of combustions; for MTBE-laden fuel, a stoichiometric ratio can be as low as 14.1:1). Vehicles using an oxygen sensor(s) or other feedback-loop to control fuel to air ratios (usually by controlling fuel volume) will usually compensate automatically for this change in the fuel's stoichiometric rate by measuring the exhaust gas composition, while vehicles without such controls (such as most motorcycles until recently, and cars predating the mid-1980s) may have difficulties running certain boutique blends of fuels (esp. winter fuels used in some areas) and may need to be rejetted (or otherwise have the fueling ratios altered) to compensate for special boutique fuel mixes. Vehicles using oxygen sensors enable the air-fuel ratio to be monitored by means of an air fuel ratio meter.
    Lean mixtures produce hotter combustion gases than a stoichiometric mixture, so much so that pistons can melt as a result. Rich mixtures produces cooler combustion gases than a stoichiometric mixture, primarily due to the excessive amount of carbon which oxidises to form carbon monoxide, rather than carbon dioxide.The chemical reaction oxidizing carbon to form carbon monoxide releases significantly less heat than the similar reaction to form carbon dioxide.(Carbon monoxide retains significant potential chemical energy. It is itself a fuel whereas carbon dioxide is not.) Lean mixtures, when consumed in an internal combustion engine, produce less power than the stoichiometric mixture. Similarly, rich mixtures return poorer fuel efficiency than the stoichiometric mixture. (The mixture for the best fuel efficiency is slightly different from the stoichiometric mixture.)
    #11
  12. f800gs2010

    f800gs2010 n00b

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    This is my first posting:

    The Extended version of the accelerator plug came in today, it took a week to get to Turkey where I live, which is very fast.

    Anyway the install was very easy the two plugs go just between the AIT plug below the fake tank. So it takes 6 screws too loosen thats it. Just tie-wrapped the sensor on my Desierto 3 screen metal parts behind the black plastic.

    First impression when i started was that the throttle response was a lot smoother. :clap

    The test ride: I live in the middle of nowhere and need to ride standing over some hills through the dirt/mud (depending on weather) to get to the road, my immediate idea was that the snatchiness of the throttle has gone away, much more controllable !

    Also when you release the throttle the abrubtness /sudden cutoff has gone away.

    The engines revs up a bit smoother than before, I must say the Leovince Carbon exhaust improved this as well.

    I think its a lot easier to ride in 1st gear as before and the engine smoothness has improved for sure. It may not be a big performance increase, but as the Germans say the Laufkultur / "Running Culture" has definately improved.

    Overall a well spent 50 Euro, will see how much more or less of the expensive juice the bike will take. Maybe off topic I fill with 97 Octane and also have the feeling the bike runs better on 97 than 95, maybe its just in my mind. The reason for this might be that in most countries (also in Europe) that 95 Octane is not really 95 but of lesser quality. (according to my brother in law, who has studied chemicals)

    Want to try out a new air-filter when I have my next service and see if this also makes a difference.
    #12
  13. HighFive

    HighFive Never Tap-Out

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    My Accelerator showed up today! Took exactly 2 weeks to arrive from Belgium. This is the extended version...and cost me about $75.

    [​IMG]

    I'll hook it up tonight and post my findings after a few rides (hopefully later this week). Its raining hard today, plus my rear wheel is off due to some bearing issues....:huh (surprise).

    BTW, nice first time post....f800gs2010. Appreciate the feedback. I'm anxious to compare mine to that. I don't need more power. I only purchased this devise in hopes for an easy cheap solution to smooth out the throttle off bottom and eliminate the stumble (slight hesitation) in 2nd gear. If it doesn't get the job done (fully), I'll be adding a fuel programmer to dial it in like I want.

    HF :thumbup
    #13
  14. EnderTheX

    EnderTheX Dirt Rider

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    Welcome to the asylum! [​IMG]

    Thanks for the write-up, I am definitely getting one! I need to tame that throttle to keep myself from getting in trouble in rough stuff like the big loose rocks that recently totaled my bike (technically it was my inexperience as a rider and faulty technique that caused the accident but whatever...).


    Your quote above made me giggle, I'm part German and I love all the quirky phrases they have!!! :freaky
    #14
  15. HighFive

    HighFive Never Tap-Out

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    Ok...just installed my Accelerator. Only took about 15 minutes. Piece of cake!

    I put my probe right here:

    [​IMG]

    [​IMG]

    [​IMG]

    Then, just plug & play on the other end at the airbox,

    Fired the bike up and let it idle about 60 seconds...to find itself. Then, played with the throttle.

    Holy Smokes! :smile6 This feels fantastic!. Very smooth off idle. The twitch indeed seems gone. I can't wait to ride the bike and see how it feels under load.

    But I'm kind of grounded at the moment....missing a rear wheel. :ddog

    HF :thumbup
    #15
  16. EnderTheX

    EnderTheX Dirt Rider

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    Ya know..... I am a mechanical engineer and I never really dove into engine management as much as I should have. The claims and testimonials for these modifications are enough to make someone think they are worth their weight in gold.

    How about someone with an intimate knowledge of the engine and the possible short term (cutting out on a tough uphill at 12k feet when you need it most) or long term (engine wear, gunk, etc) chime in an tell us how it really is?... (Joel!?!)

    Not that I don't trust the infinite wisdom of Griz (wink [​IMG]) and the gang but serious hype always gets me on edge (I didn't see Avatar until it came out on BlueRay)...
    #16
  17. HighFive

    HighFive Never Tap-Out

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    I FINALLY got to ride my bike around a little (in the dark) last night after getting my rear wheel back on. I was sooooooooo itchin to feel the effect of this Accelerator plug & play device.

    Ho-chi-momma! :eek1 It is radically better. The off idle snatch/twitch is totally gone. :deal Very smooth roll-on off idle. Feels fantastic.

    It definitely has given the bike some more fuel down low....where it so badly needed some.

    Now then, I only putted around the driveway and neighborhood street a bit.

    Hold the fort, while I take it out for a real ride today and put it under load. The theory is sound. Cooler temp reading should order up more fuel from ECU....goes to reason.

    This devise is genius....pure Genius. I bought the extended version and it only cost me about $75. Took exactly two weeks to arrive in the mail.

    THANK YOU Mark! [​IMG]

    I don't think I'll have to buy a fuel programmer now. All I really wanted was to smooth out the bottom off idle and eliminate those pesky stumbles (delays). So far, so good...

    HF :thumbup
    #17
  18. HighFive

    HighFive Never Tap-Out

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    Ok...have ridden it plenty enough now to say, "This thing just plain works!"

    Call it stiochemetric voodoo are whatever you want. I like it. :thumb

    The stumble is also gone when taking off hard in 2nd gear. There is only a very faint hesitation which is hardly noticeable. Nothing like before where I would actually rock forward in the seat.

    Super Thanks to the inmates who pointed me toward the Accelerator.

    HF

    p.s. I assume the Booster Plug achieves a similar result. But have no experience with it.
    #18
  19. The Griz

    The Griz Long timer

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    Hell yeah, High Five. I'm glad you like the result. I've got my Booster Plug Mk2 on the way as we speak! I don't really give two shits to know EXACTLY how the thing works either. All I know is that a lot of the snatchy uncontrollable throttle crap we be gone. The lean surging at lower RPM's will be gone. The bike will be more enjoyable to ride. End of discussion for me!
    #19
  20. The Griz

    The Griz Long timer

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    #20