nAst1: Progress and Concepts Thread

[robertisaar]

pain is art.

think of the "art" that could be had if i go through with my triple 7727/7730 project.

[Mars]

Hmmm. sounds like a PITA.

[robertisaar]

that's true.... using a 7730, would either need to add in the missing RAM and addressing chip directly to the board or use the NVRAM hack and i would have to add in support for that by moving addresses around.

[caffeine]

I think Mars needs the 2/3bar support though.

[robertisaar]

the spark/fuel cut code works on a 80Hz loop, that's not a lot of time to accelerate past the desired speed, but it may be enough with no load on the engine. so, lower away, if you feel it's necessary. widening the kill / restore gap or lowering both overall is the way to go.

RPM and RPM X 50 can disagree with each other at times when RPM changes rapidly. the way i have their calculations setup, RPM X 25 is done in the factory location of A71C, but RPM X 50 is done where i intercepted the routine at A558. the RPM X 50 loop is done on an 80Hz loop, the RPM X 25 value is calculated by a subroutine in 2 different places in the code(A763 and A614), but IIRC, both of those are 80Hz loops as well, they just may not be the same loop. point is, if they don't agree, your actual RPM is probably between the two values.



Mars: i don't see any reason why it couldn't as it doesn't use the extended RAM.

[caffeine]

Maybe if I set the 'enable speed' lower than I have it then spark will be cut for a longer duration and stay at the desired rpm?

[caffeine]

Just looked at my log and it was obviously slow because after I shifted into 2nd I was only at 1600 rpm lol. Still making 3 lbs of boost at that RPM though. Boost starting increasing again at 2500 and by 3200 or so it was getting back to full boost. And I stopped accelerating at 5200 rpm or so (sucks not having a working tach yet ).

Interestingly with the spark cut limiter enabled the RPMs were going between 2400 and 2700 with the rev limiter set at 2400. Although its somewhat hard to say exactly because the engine speed and engine speed x 50 are inconsistent with each other. Like I'm going through the log at 25% speed and there's spots where one reads 2600 and the other reads 2450, for example. Don't know what's up with that. I'm only seeing that inconsistency when the limiter is enabled though.

[ericjon262]

Jealous.

[caffeine]

Interestingly enough the spark limiter isn't nearly as harsh feeling as the fuel cut was either. Much louder though

[Mars]

YESSSSS!!!!

Can we get this to work on a 7730 somehow ?

[caffeine]

Well I only have 225/60-16s on the rear right now but have some 275/40-17 street slicks for autoX that should grip much better. Also dialling back the dampening on the rear end will help with launching. I'll find out more at the track on Sunday as long as I get off work in time.

[robertisaar]

if you're spinning that badly with the 3.23s..... can't imagine what the extra 27% of the 4.11s will do. posi or locker or ???

[caffeine]

Since I know everyone wants to hear glorious flame-shooting goodness. It actually sounds sooo much louder in real life haha.
It built full boost (9psi) at 2400 rpm. It was a little laggy when I shifted into 2nd probably because I wasn't going very fast (spinning in 1st) and the new 3.23 rear end is awful compared to 4.11s.

[robertisaar]

played with it more, more discoveries:

when using the spark cut rev limiter: with an automatic, if in p/n, fuel rev limiter is still possible. this is probably a good thing. when in drive(or in the case of anyone else using the 4 circuit decoder, anything but p/n), no fuel cut is possible. since manuals are always considered to be in drive, i checked and no fuel cut ever happens with them in my testing.

so, synopsis on the spark cut rev limiter is that it cuts only spark, except for an automatic that is in p/n, in which case it can cut both apparently. i really need to keep logs rather than short notes.



also, playing with it more, i'm not certain if the current dwell behavior will be a problem. 2 seconds is a long time to have no spark. about the only way to keep an engine overspeed for that long would be to drop down a gear when already at a high RPM and keep the throttle held open while wondering why you're losing speed.

[caffeine]

Excited to try this out!