nAst1: Progress and Concepts Thread

[caffeine]

I'm still running open loop so correct me if I'm wrong but BLM and INT can't be affecting anything.

[robertisaar]

IRT is a good thought since coolant temp does effect it, i would think it would go away pretty quickly though after any significant amount of throttle for more than a few seconds... IRT is initialized to coolant temp before startup.

your IAT sensor doesn't get heatsoaked does it? it shouldn't be very far off of ambient temps.

F104, F105, F106, F55, F50, F81, KAFTCLOW, KAFTCHI, KADSUCTA(with stock BFUZ values, this is RIGHT at the 160 threshold) are all effected by startup coolant temp and suspect to being the cause. that's ALMOST the entire list of stuff that startup coolant temp is compared against. does INT/BLM do anything odd during these events?

[caffeine]

Ya it's present after choke fuelling should be long gone. Would intake runner temp have anything to do with it? It runs leaner when started fully warmed up I've noticed but only at very light load. At medium-full load AFRs are pretty much the same as when started cold.

Is there anything that affects spark advance that could cause this behaviour?

[robertisaar]

so the issue is still present long after choke fueling would no longer be needed when started above that temp?

there aren't a lot of variables that are still active for more than a minute or two after starting based on startup coolant temp.

[caffeine]

Ok I got the AE-PE transition smooth by zeroing the 7-8 AE 'pulse' I think it's called.

But I'm still having issues when the startup coolant temp is high. It drives like a dream when started from cold or 160ish *F but I I start it hot/fully warmed up I get low-load/ part throttle bucking even when driving for a long time. I'm just not sure what values to look at to fix this.

[robertisaar]

i suck at life.... that being said, full refund offered upon request.

AE and PE at the same time.... if it's happening, it's allowed in the code somewhere. i could always add in a bit to allow/disallow them from both being active at the same time, obviously with PE being the priority. normally, by the time you would get into PE(in regards to throttle), AE would never really be needed, but due to the way AE code works with the 60V6 masks, it can still happen. an "oversight" by GM.

startup coolant temp effects a LOT of things.... from the sounds of it, you're running into issues with the "choke" values, perhaps you could see what coolant temps this is happening at and

1. richen the AFR immediately after cranking
2. make the time it takes to get out of choke fueling and into open loop fueling longer
3. both of the above

if it is a fueling issue, that's your fix.

[caffeine]

I've now dialed back AE quite a bit, but still go extra rich when PE and AE overlap. Is a PE/AE overlap supposed to happen or should AE end once PE kicks in? It doesn't make sense to me why they would overlap at all.

Another thing I've noticed is that when I start the car warm, it struggles to idle at first, but then after driving for a minute or two the idle goes back to normal. Does this have anything to do with startup coolant temp? What tables/scalars does startup coolant temp affect?

Oh also, when's the spark-cut limiter gonna be ready? I'm hoping to be doing 1/16th mile on the 5th of May so it will be important for such a short track.

[robertisaar]

sounds like AE.

the values that work for a LH0 are bound to be pretty different than what works for the 3500s. stumble/bog sounds like too much fuel, but feel free to confirm which direction it's going on the wideband. be certain to have your main VE right before messing with AE, otherwise one will cover the other and will cause you to run circles around why it works one day, but not the next.



as for why no misfire in open loop.... i wouldn't think it would be, but it's possible that your engine is just that sensitive to AFR... or with injectors as large as you're running, you'll need to turn down the O2 prop gains to keep the AFR swings a lot closer to the commanded AFR.

[caffeine]

Well today I ran in open loop again and didn't get the constant misfire even around 14.5 AFR. I'll leave it in open loop for now but I don't understand why closed loop causes misfiring...

Another thing I'm having issues with is when I give it throttle suddenly it stumbles and bogs for a bit, then catches here and there before finally going. Is this something to do with AE? If I gradually give it more throttle it accelerates fairly smooth in comparison.

[caffeine]

this is being read off of a wideband too, IIRC...

i know i've asked this a lot before, but headwork? especially anything done to the chamber itself?

No headwork at all

[Mars]

I'm anxious to see what the fuel pres. drop does... I think it may help.

[robertisaar]

this is being read off of a wideband too, IIRC...

i know i've asked this a lot before, but headwork? especially anything done to the chamber itself?

[caffeine]

I'm beginning to think you're right about it being mechanical in nature. I tried making single-fire permanent and the stoich misfire persisted. Strange thing is that when the AFR is around 12-13 there is no misfire. I don't really understand how that could be.

[robertisaar]

I've had it in open loop around stoich and it does pretty much the same thing. I was also considering reducing my fuel pressure from 55 to 45 engine off to see if that helps further.

assuming you do drop the pressure to help increase PW and it still doesn't go away, i'd venture a guess and say it's mechanical in nature.

[SappySE107]

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