About fuel cells calculation

honda69 · Post by **honda69** » Sun Aug 01, 2010 8:55 pm

My afr value are great but my graph is not smooth. I want to know how eCtune calculate the fuel value with the selected cell and the three around of it to change the good value and smoothing my graph. thanks for helping me

honda69 · Post by **honda69** » Mon Aug 02, 2010 10:23 am

My graph look like this setup n/a D15B7 Walbro 255 at 60PSI P29 pistons stock cam with 2Â°retard

Bindegal · Post by **Bindegal** » Mon Aug 02, 2010 1:54 pm

To my knowledge, the fuel/ignition values are taken from the cells and interpolated. This is all part of the standard Honda code on which eCtune (and others) are based. However, sometimes youÂ´ll find that the engine just \"wants\" some odd twists to the fuel curve. Often I have tried to even everything out, only to find that itÂ´s not working... This can be especially true for some engines with wild cams or some intake systems. Remember this is all based off a MAP sensor and not actual air flow. So which ever oddities in the engine causing different air flow for various rpm/MAP values, will be shown in the maps if you take the time to tune everything spot-on perfect. As long as you dont have fuel curves crossing, dont worry too much about it

Especially if the AFR is good and the driveability is nice. /Allan

honda69 · Post by **honda69** » Mon Aug 02, 2010 4:31 pm

My driveability is nice especially since i have retarded my stock cam to 2Â° retard. The change was impressive from low to high rpm. there is my g-tech result. I'd do more testing with cam gear in the next days Thanks a lot Allan you really helped me

TopMountGSR · Post by **TopMountGSR** » Wed Aug 04, 2010 2:10 am

You need to make the map symmetrical. Spend time manually smoothing your map. Most of the time when its calling for a dip or a spike in the lines, look above or below it, chances are if its telling you to pull a bunch of fuel, a cell close by has to much. Don't try to hit exact target air fuels, just a safe range throughout the column. Give and take, do whatever it takes to create a smooth map. The cars drive ability will reflect it.

honda69 · Post by **honda69** » Wed Aug 04, 2010 5:57 am

ok I'll try in the coming days therefore my afr can vary in light load from 14 to 15 max 15.5, mid load 13 to 14 and at wot 12.5 to 13 max 13.5? if its good i can effectively smooth the graph

honda69 · Post by **honda69** » Wed Aug 04, 2010 7:38 pm

AWESOME thank to you Dan, my graph look better and the afr stay to good value

12sec1/4 · Post by **12sec1/4** » Thu Aug 05, 2010 2:37 am

That's a good result. It's mad how much smoother that looks just by \"tweeking\" it a little bit. If you don't mind me asking, how much time did you spend correcting it? Paul.

honda69 · Post by **honda69** » Thu Aug 05, 2010 4:59 am

Approx 3 hours of street tune for the 1st step graph. And 2 hours to analyse thoroughly my last datalog file of 15 min and make my last update. Tonight i'd try it to know if it's good and if i can make it smoother

TopMountGSR · Post by **TopMountGSR** » Thu Aug 05, 2010 7:34 am

haha, glad to see you getting it, amazing isn't it. I see quite a few spots still left you can keep ironing out. Your doing an excellent job however. The symmetrical trick is one of the best I've learned, its an easy way to tell who knows what on here. Rough map, rough and 'notchy' feel. Stay away from tuners that don't understand this. Also if you ever can not get rid of a wild fuel curve that it keeps demanding.. Play with your injector offset, it will disappear..

honda69 · Post by **honda69** » Thu Aug 05, 2010 4:31 pm

yes it's amazing, i wouldn't believed that. this evening i have saved some datalog files and with the values i have glimpse i think i can make it smoother i'll go analyse files big thank for your support

12sec1/4 · Post by **12sec1/4** » Thu Aug 05, 2010 7:22 pm

Did you feel your car was rough before you started smoothing it out? The difference in graphs is like night and day... Is there a big noticeable difference in driveability? Up intill last week I would have just gone with target AFR's but now after reading this its shown me that keeping the AFR's bang on will have the injectors pumping iraticly. Common sense when you think about it!

honda69 · Post by **honda69** » Thu Aug 05, 2010 9:10 pm

Before smoothing, my driveability was not so bad. Now i can't realy feel it because the most change i have do was cell by cell when driving I didn't put previous Cal to feel the difference The only change i have noticed it's when i shifting to the second gear at wot my tyres burn a little. i hadn't it before but i'm not sure it's for that because my IAT was low today. In the next days i'll try with my Gtech to see any change and i'll post my result

JaredKaragen · Post by **JaredKaragen** » Thu Aug 05, 2010 10:59 pm

My old turbo d15b ended up with this map once...

I called it the evil eye; it was a combined result of tip in lean-ness (lower rpm) and battery offset (width of the 'eye').

12sec1/4 · Post by **12sec1/4** » Fri Aug 06, 2010 3:25 pm

Did you feel the eye?

I mean in the transition between cells, did it feel different to the rest of the map?