nAst1: Progress and Concepts Thread

[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]

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]

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]

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

[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.

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[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]

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

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[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 .

[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]

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

[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]

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]

might be normal, might not. the intake design of the 3500 is noticably different compared to the LH0 intake that the calibration was made for. a good place to start estimating what would be correct would be to see if any GM info could be dug up on what it calculates IRT out to be on it's native PCM.

removing/adding the throttle body heater coolant loop would actually change the values needed as well, along with anything else that might change the temperature of the intake manifolds, heads and TB.

i'm not saying it's the best resource, but i have a 2002 monte carlo 3400 BIN open in tinytuner, in the Fuel->MAF section, there are two interesting tables(speed density MAF compensation vs ECT and vs IAT), unfortunately neither looks very finely tuned. those look like what would be used to compensate the airmass based on intake runner temp, but the values in the IAT table are useless and the ECT table aren't completely done either. i checked from 96-05 and couldn't find any 60V6 applications that had a usable table. checked a 05 monte carlo L67 BIN and for some reason the IAT table there seems to be inverted?

[caffeine]

The IRT in the logs appears to pretty much always be around 100 *F higher than the MAT reading in cruise situations. Is that normal? MAT is usually between 70 and 90 *F, sometimes reaches 100* in slow moving traffic or when starting the car hot.

At WOT the IRT is about 60-70* higher than the MAT.

[robertisaar]

i tend to forget little details like that.... so yes, BLM and INT should be locked to 128 at all times then. how about Closed Loop Correction? it should also be stuck at 128.