Power Commander - Why do most maps remove fuel? - Wrist Twisters
 
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post #1 of 7 Old 06-21-2015, 05:50 PM Thread Starter
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Power Commander - Why do most maps remove fuel?

Hey guys,

just a quick, dumb, probably answered previously question i have that i couldnt find the answer to while searching.

close to finish on my 900rr (sort of) conversion, i am starting to play with the pc maps.

Just wondering why they all seem to remove fuel at points rather then add?

And the ones designed for more agresssive/free flowing exhaust systems seem to remove more fuel. I thought those systems would cause the bike to run lean and if anything i'd want to add fuel.

im sure there is a good/obvious reason... im just curious. Sorry for my horrible punctuation

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post #2 of 7 Old 06-21-2015, 06:46 PM
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Mostly because the 9er is horribly over fueled at every point of it's stock map, I know there's a good reason for it but I don't remember why


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post #3 of 7 Old 06-21-2015, 07:27 PM
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Quote:
Originally Posted by voodooridr View Post
Mostly because the 9er is horribly over fueled at every point of it's stock map, I know there's a good reason for it but I don't remember why
Correction: The stock fuel map is not horribly over fueled everywhere, at least not my '02 according to my installation of a A/F sensor feeding info into a data accumulation module which gave a good indication of the stock map across a broad range of operational conditions. At normal cruise throttle settings the A/F was in the 13.2:1 to 13.6:1 range: a bit fatter than stoichiometric 14.7:1 but by no means "horrible". Once the throttle is much past 40 to 45%, however, it drops into the mid to low 9s, which I suppose is intended to keep the pistons cooler than would be the case with a leaner ratio. Obviously Honda knew the average owner isn't going to use that much throttle all that often, so what's the harm in extending the life of the engine?

The tendency to ascribe a practically maliciously rich stock map is promulgated by PCIII users that are nearly as fanatical as the Ohlins owners, invariably indicating a desire to "get as much out of the motor as I can", while in reality the actual gains are minimal at best, and sometimes shake out to losses.

Bottom line: if you are looking for an accurate map there is no substitute for a dyno run, or possibly several, done by an experienced operator who then writes a custom map for your setup. Anything else is tuning by anecdote bolstered by the ever unreliable butt dyno, and that is simply a waste of time and effort.

My advice? Run it with the stock map and see how it reacts. If it's chuffing soot and blubbering by all means lean it out some, but approach that cautiously: too lean is a great way to learn how to replace holed pistons, or worse discover how much a shop charges to do it.

Rob

If it has already been done, it is safe to assume it is possible to do it.
On the other hand, if it has not been done never assume it is impossible to do it.
------- Rob --------
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post #4 of 7 Old 06-21-2015, 08:12 PM
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Pretty much what Rob said.

The fueling is all over the place across the range. It's too rich in some areas, and almost spot on in others. So you really do need an experienced tuner to really maximize the PC. The biggest gains are not in HP outputs, but in more smooth throttle response across the entire range.

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post #5 of 7 Old 06-21-2015, 08:24 PM
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Quote:
Originally Posted by SGKukov View Post
Hey guys,

just a quick, dumb, probably answered previously question i have that i couldnt find the answer to while searching.

close to finish on my 900rr (sort of) conversion, i am starting to play with the pc maps.

Just wondering why they all seem to remove fuel at points rather then add?

And the ones designed for more agresssive/free flowing exhaust systems seem to remove more fuel. I thought those systems would cause the bike to run lean and if anything i'd want to add fuel.

im sure there is a good/obvious reason... im just curious. Sorry for my horrible punctuation
I don't know what maps you are looking at, but any maps I've used that I have found to be good, plus the custom dyno map I had done, all have very noticeable plus and minus areas, as well as some no change zones.
Maps for 900 RR conversions will be different, as a result of trying to adjust for the mismatch of pipe to overall engine, intake side included.

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post #6 of 7 Old 06-21-2015, 09:37 PM
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There are some colour coded map comparisons in the Drop Box.

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post #7 of 7 Old 06-22-2015, 03:15 PM Thread Starter
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Thanks EVERYONE for your responses. I've taken Rob's post and ran with it. When i posted this i had just swapped in a more agressive map for the 900rr conversion, after reading Rob's post i decided to start from square 1 and zero out the map and ride on that for a bit and see how it felt.

I barely notice a thing. Bike runs just fine. Starting to think the PC wasnt worth it for my type of riding.

I really like when Rob responds to one of my posts... i almost always need a dictionary and here was no exception. Rob, you should put a link to a dictionary in your signature... save everyone the trouble

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