nAst1: Progress and Concepts Thread

[SappySE107]

I like the OBD2 MAF and MAP setup. I don't think a P4 can process all that though:P MAP based spark and MAF based fuel with MAP backup would be ok with me.

I am not sure on the MAF vs Altitude but I would guess that the engine will take in less air and thus, automatically correct no matter how high you get. Does the oxygen content of the air get less, or is the air simply less dense with the same % of elements? I figure its the latter.

[robertisaar]

I like the OBD2 MAF and MAP setup. I don't think a P4 can process all that though:P MAP based spark and MAF based fuel with MAP backup would be ok with me.

I am not sure on the MAF vs Altitude but I would guess that the engine will take in less air and thus, automatically correct no matter how high you get. Does the oxygen content of the air get less, or is the air simply less dense with the same % of elements? I figure its the latter.

that's the part i can't get a straight answer on.

if it is the air simply being less dense, then yeah the MAF itself will take care of it, i guess i could make the multiplier table and just leave all of the values at a mult of 1 regardless of barometric and it would be correct, but then i would need to waste time on an unnecessary 8 X 16 multiply... and taken up code space... guess i need to do some more research.

i COULD do a simple blend when the MAF - speed density(or speed-density - MAF) transitions take place, just keep track of the last BPW calculated, add it with the new BPW, div by 2 to make an average of them, then on the next cycle go with a 100% derived from one or the other BPW.



i guess it really depends on how lean i can make the MAF code as to whether or not they can be blended at all times.

[SappySE107]

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1114067/

"Although the percentage of oxygen in inspired air is constant at different altitudes, the fall in atmospheric pressure at higher altitude decreases the partial pressure of inspired oxygen and hence the driving pressure for gas exchange in the lungs. An ocean of air is present up to 9-10 000 m, where the troposphere ends and the stratosphere begins. The weight of air above us is responsible for the atmospheric pressure, which is normally about 100 kPa at sea level. This atmospheric pressure is the sum of the partial pressures of the constituent gases, oxygen and nitrogen, and also the partial pressure of water vapour (6.3 kPa at 37°C). As oxygen is 21% of dry air, the inspired oxygen pressure is 0.21×(100−6.3)=19.6 kPa at sea level.
Atmospheric pressure and inspired oxygen pressure fall roughly linearly with altitude to be 50% of the sea level value at 5500 m and only 30% of the sea level value at 8900 m (the height of the summit of Everest). A fall in inspired oxygen pressure reduces the driving pressure for gas exchange in the lungs and in turn produces a cascade of effects right down to the level of the mitochondria, the final destination of the oxygen."

[robertisaar]

so.... "inspired oxygen" drops as altitude rises, but it sounds like the actual mixture of air contains the same amount of oxygen regardless of elevation.... so the MAF should take care of it on it's own. i guess if it doesn't in the real-world, i'll have to patch a patch to add in barometric compensation.

[SappySE107]

Those articles are discussing 30k feet+. For 99.99% of us, the MAF is going to see a linear rate for air mass and oxygen. Im not driving to the top of Mt Everest .

[SappySE107]

nAst1 1.04 BP.xdf

I made a few new histograms and monitors. I use the monitor for spark now, so I can see when there is KR and not just avg or min or max or whatever. The INT is for after BLM is good and locked. I was using the STFT but this last go around I wanted to see something familiar and do it by hand rather than the auto tune file.

[robertisaar]

why upload the XDF? the ADX is what you changed.

[SappySE107]

cause I don't know what is what I see load, import, edit, new, and recent under acquisition. I don't see save for the adx file so I assumed it was part of the xdf.

[robertisaar]

when you go into the Acquisition -> Edit section, there is the option to save changes to the ADX that way.

[SappySE107]

nast1 1.04 BP.adx

And I had to add the adx file extension so we can upload them anyway

[pocket-rocket]

I took the 92 out on a small trip on "deserted private roads" today. I raise the rev limiter to a more normal level. The car still drives nice, but with less power, which is expected since it hasn't been tuned yet and is basically on a stock tune. It drove and idled fine, although at light cruise there was a slight jitter. I wasn't watching my laptop, but I assume it was the double fire and single fire switching over. Other than that, it ran fine, no DTCs set, nothing out of the ordinary that my novice eyes could pick up. It ran fine up to 7k without a hiccup. I would upload a copy of the ~10 minute run, but it's on my laptop out in the garage at the moment.

I don't mind being a guinea pig, after all, I was Ben's guinea pig for both of his DOHC chips, lol.

[SappySE107]

I was wondering why my idle kpa was in the mid 40s, when every stock 3.1 I had seen was in the mid 30s. Freescan shows 37, Tunerpro shows 43-44. I am tuning based on tunerpro, and it seems 60+ is all damn near the same if not exact so i don't know what to make of it.

[robertisaar]

i have normalized MAP being displayed in the datastream, since that is what is used for the majority of the lookups, scale of .3125 per bit with an offset of 20 kPa. you're probably used to seeing raw MAP values, which usually have been lower than normalized MAP from what i've seen. the wife's GP idles around ~38kPa normalized.

anybody got a 9396 and a MAF with a reasonable size for their motor? i have some code roughed out, but i need someone to confirm the period to Hz calculation is correct before i can write out the Hz to Grams/sec code and then the grams/sec to grams of air per cylinder code, and then finally the grams of air per cylinder to a pulsewidth code. in $2E, the MAF value is updated every reference(3 times per revolution on a V6) pulse using what would normally be the VATS circuit on a 9396. since no 9396 equipped vehicle ever had VATS from the factory, i can use ~90% of the 2E code, then just use the EE Hz to Grams/Sec code.

[Superdave]

are you sure the stock shift light tables would be sufficient? IIRC, they only go to 5000RPM.

i imagine i could impliment a "track only shift light" option that would only be used when near WOT. if you have roughly the same desired shift RPM for every gear change, that would be even simpler to code, since N/V ratios wouldn't need to be setup/checked.

the only problem is finding a suitable output to use. obviously, there would be no reason to use a PWM output for a light.

7727 equivalents: A13, A18 and D2 are the only free outputs in a normal A1 car.


A13 is a digital on/off that is normally unused, only the 90-earlier cars that are converted to $A1 use it for the low coolant light or if F31 trans is selected, shift solenoid B.
A18 is a PWM output, used for AIR divert on manual trans cars or shift solenoid A if F31 trans is selected.
D2 is a digital on/off, Ludis listed it as a relay circuit, no idea why, but it is wired a bit differently than the quad drivers, shouldn't make a difference though.

so, i would recommend D2(A2 on a 7730). i'm not sure how to access it yet though, never looked into that one yet.



side-note: i have the algorithm $EE uses to make a 16 bit grams/sec value from MAF frequency 100% decoded.

What about using the CCP pin F7?

 0348        FE    254 KCCPTM         254 SEC    IF ENGINE RUN TIME <= THIS DISABLE CCP
 0349        A0    160 KCCPTMP         80 DEG C  DISABLE CCP IF COOLANT < THIS
 034A        01      1 KCPVST1        0.3 MPH    ENABLE CCP IF MPH >= THIS (CCP OFF)
 034B        0F     15 KCCPTPSU         6 %      ENABLE CCP IF TPS >= THIS (CCP OFF)
 034C        0C     12 KCCPFLWH         3 GM/SEC ENABLE CCP IF FLOW > THIS (CCP OFF)
 034D        00      0 KCPVST2          0 MPH    DISABLE CCP IF MPH < THIS (CCP ON)
 034E        05      5 KCCPTPSL         2 %      DISABLE CCP IF TPS < THIS (CCP ON)
 034F        04      4 KCCPFLWL         1 GM/SEC DON'T DISABLE CCP IF FLOW > THIS
 0350        0B     11 KCCPCOEF        11 COEFF  FILTER COEFFICIENT FOR CCP DC
 0351        04      4 KCPMULT        1.6 %      INC CPMULT BY THIS EVERY SECOND IF PURGE ON
 0352        01      1 KCPMULTA       0.4 %      DEC CPMULT BY THIS EVERY SECOND IF PURGE OFF
                                                 AND CPMULT > KCPMULTL
 0353        80    128 KCPMULTL        50 %      LOWER LIMIT FOR CPMULT DECREMENT (SEE KCPMULTA)

If we could change 34A to RPM, we could use 34B to keep it off unless you are above 70% throttle, the rest could be adjusted accordingly...

[robertisaar]

two things:

sorry for taking so long to answer Dave, but if you want RPM to be the compare done to 34A, then in the TP hex editor(or any other you might use) change DDFF(5DFF) to $62 for RPM X 25(if you shift under ~6400) or $76 for RPM X 50. you can safely draw up to ~1 amp with that circuit, wouldn't try drawing any more than that, i've tested 1.5 amps for short periods of time without issues, but i wouldn't push it.

also, bugfix version coming VERY soon, i actually didn't realize i had two serious issues, one with the idle VE table, another with the 5200-8400RPM spark table. i have quite a changelog for this release, unfortunately i don't have it 100% tested yet, so no release ATM.