Tuning ITBs and Bin resolution

pjr311 · Post by **pjr311** » Fri Mar 21, 2014 7:27 pm

HI,
This question relates to Load resolution setting on tuning graphs.

Considering I am using ITBs and my idle value is 66%, what is the point of including "Y" values all the way down to 20%, would it not be better to change Spark advance bins for example to start at 60% to give better resolution?, also could the same be applied to fuel tables?

Many Thanks in advance

Phil R

kaeman · Post by **kaeman** » Fri Mar 21, 2014 9:01 pm

I have itb's also, I have my fuel tables layed out with the bottom bin at like 40 or 50 because it is just a course jump then when I get into the 60's the bins are very close, and up in the 90's the bins are very close, that way when the engine is where it runs the most it has the best resolution. look at my fuel ve table... it runs just fine and where the finer adjustments are needed the bins are closest together.

2014-03-21_20.59.25.msq

Post by **muythaibxr** » Fri Mar 21, 2014 9:38 pm

Why not use ITB mode and tune the curves for it to maximize usable resolution?

pjr311 · Post by **pjr311** » Fri Mar 21, 2014 10:30 pm

I am already using ITB mode, how does that help?. You still only have between say 60 -100 of resolution. What am I missing here ?

kaeman · Post by **kaeman** » Fri Mar 21, 2014 10:49 pm

did you reconfigure your load bins to better match your engine like I did mine or are you still using the bins in the initial set up? I know the only time my engine sees anything below 60kpa is on full decel from high rpm... then it will go down to 18 and 20... but I am letting megasquirt guesstimate the correct fuel in that area of the power band....(full decel) I just made it so that I have more bins to work with in my usable load range.... it made tuning lots easier... and the engine runs better.

pjr311 · Post by **pjr311** » Fri Mar 21, 2014 11:00 pm

No, not yet.. It makes sense what you are saying. but are you using ITB mode or straight SD?

Post by **muythaibxr** » Sat Mar 22, 2014 4:38 am

ITB mode allows you to set the load at switchpoint, so you can make the SD part have fewer bins or more bins if you want.

Post by **muythaibxr** » Sat Mar 22, 2014 4:41 am

You want Y values that are down low because once you start revving it up, you can actually get into the 30's and 40's with the throttle open and you'll want to be able to control how much fuel is injected there. ITB mode will let you control the resolution of SD compared to AN with the load at switchpoint curve.

kaeman · Post by **kaeman** » Fri Mar 28, 2014 7:24 pm

the only time my engine ever see's 30's or 40's is in decel from higher rpm.... all my datalogs only show in the lower kpa during decel at higher rpms. Decel from cruising speed doesn't seem to dip down into the 40's.

I had to trim the file twice to make the 1 meg limit. but you can see I don't get into the 40's during normal driving.

2014-02-01 new lag setting driving intown_modified_modified.msl

pjr311 · Post by **pjr311** » Fri Mar 28, 2014 10:05 pm

Hi, Yes I am confused here. The only time I see 30-40 is decel from high revs. So I dont see how the lower values are of any use, and would of thought more resolution between 70-95 to be better.. but Im happy to be wrong if someone could explain why

Post by **muythaibxr** » Fri Mar 28, 2014 10:22 pm

How are you setting idle? Are you setting it using the throttles themselves? Maybe that is why since they can't shut as much. My ITB engine had them from the factory, idles almost completely on an idle valve and idles around 30-35 kPa at 800 rpm, and dips into the teens on overrun.

So I actually need some bins down there (3 or so) to avoid popping from the exhaust coming on and off overrun and to control speed going down hills. Basically just adjust the load at switchpoint curve to maximize the resolution. I tune for smaller SD at lower revs since just cracking the throttle makes the MAP go straight to 90, then I tune for smaller AN at higher revs since speed density works better there.

pjr311 · Post by **pjr311** » Fri Mar 28, 2014 10:46 pm

Hi, No mine idles at 67Kpa, which i believe is pretty normal with a mild Cam, I don't uses idle control valve.

Post by **muythaibxr** » Sat Mar 29, 2014 5:53 am

That might be why you don't get much vacuum even on overrun.

kaeman · Post by **kaeman** » Sat Mar 29, 2014 10:12 am

my old hilborn setup is a constant flow fuel injection manifold from the early 1960's, I made them efi using conversion parts I made myself, and there is no provision for an idle control valve, I have been driving with this system using the ms1extra for several years....I just upgraded to the ms3 and am starting over, when I did my ms1 they didn't even have an itb mode, so I am tuning my ms3 in speed density, I want to get a good running tune in the mode I have been using before changing to itb mode. Using datalogs I found that my engine idles and runs in the 60's low 70's bins unless I accelerate hard or decel hard. during rapid decal from high rpms I will see down as low as 18kpa, but the engine doesn't back fire or pop through the exhaust, so I figure the megasquirt is extrapolating the lower bin values correctly.

I haven't tried the itb mode yet, or alfa n for that matter.... just been using sd mode all these years.
it wasn't until I upgraded to the ms3 that I even found out about the itb mode...

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