To tuners. Does AFR fluctuate?
It does a little, AFR tables are TP (Throttle Position) and RPM's, it doesn't take much for a change but in a simple short answer YES, the AFR will move a few points either way.
Stellar HDF Member
Joined: Sep 2007
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From: Vancouver Island B.C.
Absolutly the afr will fluctuate. That is why the ve tables have to be calibrated. I have attached the afr line from a 20% throttle pull. This not from a stock bike, but demonstrates why a bike needs to be tuned.
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Cruiser
Joined: Jan 2010
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From: MD
I would like to know if you keep bike at the same RPM and throttle% if AFR is steady.
It seems like my AFR fluctuates and I am worrying if it is normal or I have ignition or injector problem.
I am adjusting AFR and I have to do it by average number.
It seems like my AFR fluctuates and I am worrying if it is normal or I have ignition or injector problem.
I am adjusting AFR and I have to do it by average number.
What are you using to read your A/F? Are you riding it while doing it? Do you know what TP you are in when making adjustments? Are you datalogging info while riding then making adjustments? What tuner are you using?
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Cruiser
Joined: Jan 2010
Posts: 141
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From: MD
I just realized that PC III changes fuel number gradually between cell.
So you are not reading your A/F, I take it you watched it on the dyno and saw it fluctuating there? The cells in PC are changes over stock, whereas if all the cells were zero you would be running stock, any positive numer is richening (adding fuel) to that specific area ocer stock. So if your cell at 30% TP and 4500 RPM's is 7, than at that specific point when your bike is there it is adding that much fuel over stock. Just the opposite for any negative numers in the cell. If your MAP is set to advanced mode, then you can tune each cylinder independantly of each other. If it is in basic mode then both cylinders are tuned in unison. You can start to see what is involved in a proper dyno tune. The tech makes a number of passes at all the respective throttle positions and records the A/F over the RPM range, then he goes and adjusts the cells that corespond to the A/F line he just recorded. It is not uncommon for the A/F to fluctuate a little bit, I wouldn't be concerned. Just average out what it is saying at that spot and there you have it.
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Road Captain
Joined: Jan 2007
Posts: 605
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From: Minnesota
Just changed slip ons from old SE IIs to Rineharts. Had my bike dyno'd when I changed cams in October, so this was just a retune. My AFRs at WOT were around 13.4 at previous tune. The are now 12.8 from 2800 rpm, 13.0 from 3200 rpm to 3700 rpm, then drops to 12.9 thru 4200 rpm, then back to 12.9.
I'm assuming the variance is ok (?). What about the absolute values. Is 13.0 ok or should it be averaging around 13.5? My tuner said that in my crusing range, the AFRs were about 14.7. Sorry, but the AFR stuff is a little "Greek" to me.
I'm assuming the variance is ok (?). What about the absolute values. Is 13.0 ok or should it be averaging around 13.5? My tuner said that in my crusing range, the AFRs were about 14.7. Sorry, but the AFR stuff is a little "Greek" to me.
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You are likely seeying a fluctuation in the narrowband gauge you are using which is essentially a switch. A wideband sensor uses a controller which determines the sampling/buffering.
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Jamie Long / Fuel Moto USA
The USA's Leader V-Twin EFI & Performance www.fuelmotousa.com
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Jamie Long / Fuel Moto USA
The USA's Leader V-Twin EFI & Performance www.fuelmotousa.com
Contact 920-423-3309
Email jamie@fuelmotousa.com
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