nAst1: Progress and Concepts Thread

[caffeine]

I was logging the other day and took the engine to about 6800 rpm, and noticed in the log that the "Engine Speed" value stops increasing at 6375 rpm, and the "Engine Speed x 50" value starts increasing in 100 rpm increments after 6400. I'm thinking this is a bug? I can't see anything obvious in the datastream definition that prevents showing values above 6375.

[robertisaar]

should be 50RPM increments.... i'll verify it on the bench if i can, i should probably retain logs of when i do bench runs for reasons like this.

engine speed is supposed to stop at 6375RPM since that's the limit of an 8 bit variable with a multiplier of 25 (i.e. 255* 25 = 6375)

but engine speed X 50 should still be in increments of 50, not 100, regardless of RPM.

[caffeine]

Ah that makes more sense now. Any more progress on you-know-what?

[robertisaar]

no, i keep getting caught up with stuff around here, never have enough time to sit down and get it all done in one shot.

[caffeine]

Interesting thing I just discovered; the fuel-cut 2-step still builds boost for me set at 2400 rpm, but only 2-3 psi. Makes me wonder how much spark cut would build .

[pocket-rocket]

Interesting thing I just discovered; the fuel-cut 2-step still builds boost for me set at 2400 rpm, but only 2-3 psi. Makes me wonder how much spark cut would build .

Or a customizable spark retard under 2 step

Sent from my HTC One X using Tapatalk 2

[robertisaar]

Interesting thing I just discovered; the fuel-cut 2-step still builds boost for me set at 2400 rpm, but only 2-3 psi. Makes me wonder how much spark cut would build .

with a wide open throttle and fuel being delivered on and off to keep it around 2400 RPM, i can see a little boost being made, since the turbo will certainly be getting some energy sent through it, enough to spool it to pass the boost threshold anyways. with fuel always being delivered, but spark being cut/delivered based on RPM, it will probably be a bit higher for a given RPM since you'll probably have some fuel combust on it's way out of the exhaust.

Or a customizable spark retard under 2 step

it's not a bad idea....



i think ideal would be constant fuel delivery with spark being cut above a certain RPM threshold, but with a bit of a twist... near the cut threshold, instead of a total spark cut, significantly reduced timing(so that the engine won't easily accelerate past the cut threshold and cut/deliver/cut/deliver, probably have to fire ATDC) so that a constant stream of high heat exhaust gasses will get to the turbine. it would be absolute hell on the exhaust valves, but you would have the full air/fuel charge and the ignition necessary to fire it off powering the turbine.

[pocket-rocket]

I'm sure the cars with functional cats would prefer retarded timing vs full spark cut under a two step that retains fuel delivery. At that point it would double as anti-lag for boosted cars.

Sent from my HTC One X using Tapatalk 2

[robertisaar]

true. with that retarded of timing, you could also consider it a cat superheater too.

[ericjon262]

Is this stuff ready to use ? Can I try it on my setup or are you guys still in the testing phases ? Sorry don't feel like reading 40 pages...

you only had to read 36... I just read 48 pages...

on the spark retard 2 step, one of the guys on PFF wired a switched ground into his IAT sensor, and then commanded way reduced timing when the IAT saw ground.

http://www.fiero.nl/forum/Forum1/HTML/091053-4.html

work in this case? I don't know, but it's a easy button for sure.

this has me tempted to go OBD1 now... I like the idea of having tables that cover my RPM ranges.

[robertisaar]

doing that is one hell of a hack method.... lying to the ECM about the air temp will cause all sorts of unintended consequences. i did add in a table that allows for different amounts of advance based on IAT(or IRT, if selected), but that's not how it's intended to be used.

[ericjon262]

doing that is one hell of a hack method.... lying to the ECM about the air temp will cause all sorts of unintended consequences. i did add in a table that allows for different amounts of advance based on IAT(or IRT, if selected), but that's not how it's intended to be used.

yeah, but it worked...

[robertisaar]

so does a 1930s vintage carbeurator..... doesn't mean i'll ever use one by choice.

[Mars]

So It seems that someone figured this spark cut thing out ? posted on thirdgen.org...

Is that patch available to everyone... ?

[robertisaar]

i think i gave out the info i used to make my initial version and that was used by bl85c(???) to patch into 6E or code59, i forget.... anyways, i see how he did it, not very different than what i did, in fact, he may have solved my inconsistency issue.

here is the code i saw:

      ;
        ; Disable EST
        ;
D722:            CMPB  LC500   ; Compare to RPM for Disable EST
D725:            BLO  LD74A   ; Branch if Lower
D727:            CLRA
D728:            CLRB
D729:            STD     L3FDC              ; SPK Dwell period cnt'r
D72C:            JSR     LF4EE              ; SHORT DELAY
                                                             
D72F:            STD     L3FE6   ; SPK Dwell Cnt'r 
D732:            JSR     LF4EE             ; SHORT DELAY
                                                             
D735:            STD     L3FE8               ; CURRENT EST FALL-LAST EST FALL
D738:            JSR     LF4EE             ; SHORT DELAY
                                                             
D73B:            STD     L3FF6               ; EST FALL CNT'R
D73E:            JSR     LF4EE             ; SHORT DELAY
                                                             
D741:            LDX     L3FEC              ; B Cnt'r last ref
D744:            JSR     LF4EE             ; SHORT DELAY
                                                             
D747:            STX     L3FE4              ; B Cnt'r Bgn nxt Dwell
D74A:            RTS

since i already have the "framework" portion done, it won't take me much time at all to add in a few more commands... maybe something i'll be able to do tomorrow while the wife is photographing a wedding.