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Is idle ve necessary? No, not necessary. A clean stable idle can be accomplished without it. It just gives extra resolution around the idle specific cells. I have mine setup for anywhere my idle would be with varying loads and with ac and all my lights on or every accessory off.
You can also use timing correction to get a more stable idle.
When my car was still running a 1.6 engine and stock 1.6 injectors in batch firing, I had good results using idle ve, idle advance set to 10 degrees at load of 25, 35, 45, and 55, and an idle rpm timing correction curve that was a little bit aggressive. The megasquirt will use timing correction in addition to the idle air control valve to keep a more consistent idle.
Something like this helped. I set my afr for idle at 14.5.
Oh god idle air valve, that is a story for another day, have my ISC unplugged atm because I was getting wild behaviour with ms, not sure why. Just cranked my idle screw, it idles at about 1k rpm. For the time being it works and doesn't die on cold start, so Ill get to that eventually. A topic for another post.
Here is my updated table, I probably went overkill but I am really starting to like the looks of it. Also rebinned to get more granularity through the midrange. Plus really did not need 2 columns for idle.
Re: injectors, if I have trouble with VEAL / ve analyze ill swap em I guess, no e85 in the great white north.
I run idle timing correction but not idle advance. If you are running a constant 10 degrees is it doing anything? At idle and below the benefit of increasing the advance plateaus at about 16-18deg. At -300 you would be at 28 and at -100rpm 20BTDC?
I run idle timing correction but not idle advance. If you are running a constant 10 degrees is it doing anything?
At the moment I am just running "idle valve type = None" with my idle valve unplugged. And my idle timing as specified in my ignition table a few posts above, it idles and doesn't die on cold start so sort of on the back burner for now.
Edit: oops didn't realise that was directed at andy
I run idle timing correction but not idle advance. If you are running a constant 10 degrees is it doing anything? At idle and below the benefit of increasing the advance plateaus at about 16-18deg. At -300 you would be at 28 and at -100rpm 20BTDC?
The idle advance is to overwrite the ignition table. If I am idling with my ac on, my kpa could be 50 and my rpm's could be 1050 or 1100. I want that to run 10 degrees. For tip in, If I am driving from a stop I want to not have 10 degrees at that rpm / kpa row because I am driving not trying to maintain a solid idle. The idle advance only happens when in closed loop pid idle. It works well.
Yup, it can ad that much timing. It corrects well and keeps for an even steadier rock solid idle. My radiator / fan setup is a single spal fan that is about 14 inches large. When the fan turns on the current inrush is enough that the car wants to stall. I think a typical stock fan current inrush is something like 10 to 15 amps. This one I think is in the range of 28 to 30 amps. On top of the separate fan settings kicking up the iacv, the timing correction adds more timing because the rpm's drop a bit. This all works together to help keep me at a solid idle.
At 600-700rpm, 100-200rpm dip I think 15 degrees will have a higher output then 25. Max cylinder pressure should occur at 18deg ATDC. I'm running two 12" spal fans with a total draw of 18amps. I had issues but have it handled with a more mild correction. Instead of running the idle advance I just have all of the cells in the idle area at 12 degrees. I guess its similiar I just went with this approach because it seemed less complicated.
Originally Posted by andym
The idle advance is to overwrite the ignition table. If I am idling with my ac on, my kpa could be 50 and my rpm's could be 1050 or 1100. I want that to run 10 degrees. For tip in, If I am driving from a stop I want to not have 10 degrees at that rpm / kpa row because I am driving not trying to maintain a solid idle. The idle advance only happens when in closed loop pid idle. It works well.
Yup, it can ad that much timing. It corrects well and keeps for an even steadier rock solid idle. My radiator / fan setup is a single spal fan that is about 14 inches large. When the fan turns on the current inrush is enough that the car wants to stall. I think a typical stock fan current inrush is something like 10 to 15 amps. This one I think is in the range of 28 to 30 amps. On top of the separate fan settings kicking up the iacv, the timing correction adds more timing because the rpm's drop a bit. This all works together to help keep me at a solid idle.
Update: finalized my table and have been running veal for the last few days, seems to work pretty well and I have a half-decent ve table now. No audible knock via det cans using this ignition map that I stole from @Braineack on trubokitty.com.
One thing I have been struggling with is maintaining constant AFR at WOT, ill do a pull and it'll track 12.7-12.6 perfect, then ill hit the brakes do it again and it'll lean out and track 12.9-13.0, right after. Could this be a heat soak / MAT correction issue? Will post some clean logs once the weather gets un-rainy here.
TLDR: fuel map is getting decent, sometimes leans out at WOT
04-26-2020, 05:50 PM
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