Stage 1 Fuel Management - AIM called out
Just got the new issue of American Iron yesterday. In the Letters section on page 32 and 34 is a letter to editor, Chris Maida, calling them out on conflicting and confusing articles and past issues about whether fuel management is truly needed, with stage 1 upgrades, or not on today's EFI Harley's. I won't retype the entire letter here but references are made to the April '08 issue where they installed the S&S quick setup with no ECM calibration and boasted that, after running the bike for 10 minutes, the ECM adjusted itself for air/fuel and needed no add-on fuel management. Then, in Sept. '07, an article in "HOG Helpline" stating that "...when changing intake or (notice the word OR not AND there?) exhaust tracts you need to change the fuel map at WOT and possible at idle". And one more reference to a Sept. '06 article "How it works: DrDyno (Fred Eno)" where, among other things, it was quoted "...about half of all Twin Cam Harley engines are rich enough from the factory, and do not need fuel changes for a pipe and air cleaner upgrade (this may explain why many of us have mixed results with certain setups)."
Chris Maida's reply was interesting. Probably worth buying the magazine alone if this subject often perplexes you as much as it does me. Again, I won't type all of it but I'll add this quote: "Regarding how to know if the changes you want to make will require a fuel adjuster, the short answer is you don't. And that leaves you with two choices. Option I: make the intake and exhaust changes and then check the air/fuel chart that the dyno provides. If the ratio is running too lean, add a fuel adjuster and dial it in. Option II: just go with the fuel adjuster from the get-go, since it will definitely give you more power, even if the stock ECM can adjust for the changes. After all, the ECM will keep the air/fuel mixtures very lean to meet EPA requirements. If you don't care about that, a richer mixture is definitely going to give you more power."
Another part of the letter points out that the published article on the S&S quick setup did not show the air/fuel mixture on the dyno chart. I didn't even notice that when I read it. Chris's response to that was: "... though we didn't print it we definitely checked it. In fact, we had a fuel adjuster on hand, but, as our S&S contact told us, we didn't need to use it." He also said: "the stock ECM was able to adjust for it and keep the fuel/air mixture rigth at the H-D and EPA-dictated ratios after being run for about 10 minutes".
Just posting this for FYI - not trying to start yet another "argument" over what's needed for stage 1 and what isn't. After reading this, I do think they agree that the bikes are mostly on the lean side to begin with and the best you are going to get with no fuel management is a bike just as lean as it already was. And, while a fuel adjuster may not be necessary in all cases, they certainly don't hurt if you want a little more "juice".
AW
Ihave done back to back testing that you can see how the stock EFI has moved the maps around to account for the changes. Way cool stuff. IM me for links to the screen shots.
AW
Any help appreciated, thanks.
From my experience on owning two new 2008's, they do seem to be rich enough from the factory, you would probably be ok with no fuel management. I have a fuelpak however, just to be safe.
The Closed Loop AFR will be between 14.7 and 14.1 depending on what you have the Bias table set at and how accurate the 02 sensor is. If you don't have a SERT you can't set the Bias tables so your running what the MoCo installed in the ECM and Lord only knows what they do, I would say your running 14.6 to 14.5 with a stock ECM.
The Open Loop at WOT is set at 12.8 to 12.5 depending on what model bike you have. There is a PE table in the ECM that will richen the mixture vs Time at WOT, ie...the longer you have the throttle wide open the more the fuel will richen the mixture to cool the bike down and lube the cylinder and piston to stop seizer.
This is what the stock ECM has for you, it will adjust the AFR with the AFV's (IN 07 an up) but only to the AFR in the box, if you start making mods other than a set of pipes I would definitely get a fuel modifier of some sort to get your desired AFR. If you can afford the SERT, Pro Tuner, Power Commander, or wait for the TTS V-Tuner do so, I've been tuning for years and I'm telling you the DFO's like Fuel Packs, Terry II, Race Fueler and the likes are a waist of money.
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When you say 30% do you mean thatone (1)cell can be adjusted as long as it is within 30% of the called for VE new or only 30% of all the cells for both the front and/or rear cylinder can be saved? If it is just 30% of the total cells saved, is it 30% for each cylinder or for both combined?
Are the saved VE settings lost each time the ignition is turned off or are they saved for the next start up?
Thanks,
Chris
The Best of Harley-Davidson for Lifelong Riders
Justtwo quick questions for you Doc.
When you say 30% do you mean thatone (1)cell can be adjusted as long as it is within 30% of the called for VE new or only 30% of all the cells for both the front and/or rear cylinder can be saved? If it is just 30% of the total cells saved, is it 30% for each cylinder or for both combined?
Are the saved VE settings lost each time the ignition is turned off or are they saved for the next start up?
Thanks,
Chris




