Other Megasquirt Updates
I recently leaned out my cruise fuel ratios down to around 15-
After a hot shutdown, my AIT will shoot up to around 50'c -
First you need to edit your "..\MegaTune2.25\mtCfg\msns-
curve = clt_IATCorrC, "Coolant corrected Air Density, see Settings", 9
topicHelp = airdenHelp
columnLabel = "Temp", "Offset"
xBins = IATCTemp, mat
yBins = IATCorS
gauge = afrGauge
Next from in megatune, from Advanced | Coolant Related Air Density:
For the "reduce correction at RPM", I set these values far past my red line to effectively
disable the function. I done this to reduce the amount of variables, if you are just
trying to correct a hot restart problem -
here are my settings:
To get the initial values, I took what my AFR ratio would be at normal idle lets
say 13AFR and the ratio I get after a hot restart which is 14.5AFR. I divide 13 by
14.5 which gives .89 -
I then done a similar exercise with my cruise afr's at elevated temperatures (15 vs 16) @ 40'c which gave 7%. From there I just made a nice curve starting from around 30'c
After all that was configured and checked on the stim I put it on the car and went out for a drive. I allowed the car to warm up gently to get around 20'c air inlet temperature, I then pulled over and made a note of my idle AFR(~13). I then drove a few hard miles to get the engine bay very hot, then pulled over. Already I could tell the correction was working. My AIT was 40'c but I still had a reasonable mixture and nice idle.
I then shut the engine down and watched the AIT rise to around 50'c through heat soak. I then restarted the engine and loaded up the tuning graph. Essentially all I did was tweak the values in the graph to maintain my desired AFR in the window. As the inlet temp slowly dropped down from 50'c I just kept tweaking the values.
Back out on the road, I notice my cruise AIT temps were slightly richer than desired, so I adjusted the correction down a little. This is where you would use the RPM reduction function to start reducing the amount of correction once you are away from idle.
The car now restarts and idles nicely after a hot shutdown, which is a problem I have put up with for years.
Information from this MS Extra Thread.