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I have a 97 Miata that I just installed the full MKturbo kit on. Has the MS3 pnppro. Flowforce 640cc injectors. IAT sensor is on the cold side of the ic piping just after the ic. The car runs and drives great...….except for on hot starts.
If I drive it for 30-40 min and run into the gas station or something. Come out 5 minutes later and start the car and after the ASE is done the car doesn't want to idle. Idle oscillates real bad and the AFRs will go into high 17s, it will then stall. I have to feather the throttle for around a full minute, before it will calm down and idle. Even then, the AFRs will be in the 15s, not around 14.7 where its set. I have adjusted the ASE a little bit, but its not helping probably because ASE is only going for the first few seconds after start up. I live in Georgia, so I only imagine this is going to get worse as it gets hotter outside.
I have used the search button and found that many others have had this issue; but I haven't really seen a threat where there was a definitive "fix" for it. I have read to go into air density settings. On Megasquirt there is a MAT/CLT correction and a MAT Air Density Table. Under my MAT/CLT corrections options its all zeros in the %CLT and from 50000 to 650000 in the flow row. On the MAT Air Density Table there is air temp from -40 to 248 and correction from 125.7 to 96.0. Can anyone who has had this issue and fix it share their settings? I am not sure which one of these I should adjust. the MAT/CLT correction isn't on at all because is all at zero. I took a datalog from yesterday of the issue and it had the IAT at 82. That doesn't seem too high to me to cause an issue. Maybe Im too dumb to understand so please enlighten me! MAT Air Density Table MAT/CLT Correction
How long after start does your EGO take over? Make sure it has ~15% authority at idle, and when super super hot, it’s at 100% and 14.7, not 105-110% and 14.7.
Mat correction is not what you want to mess with. When you tune you can control how much additional fuels the MS gives for ase after start and in a separate table you can control for how long ase lasts. It sounds like your ase fuel supply is fine just not for the duration. Go to the ase table and make it so that when hot Temps greater than 185, ase lasts longer. Ase can be calculated in either engine cycles or time. Determine which one you want to use and make ase last longer. Problem solved.
How long after start does your EGO take over? Make sure it has ~15% authority at idle, and when super super hot, it’s at 100% and 14.7, not 105-110% and 14.7.
Mat correction is not what you want to mess with. When you tune you can control how much additional fuels the MS gives for ase after start and in a separate table you can control for how long ase lasts. It sounds like your ase fuel supply is fine just not for the duration. Go to the ase table and make it so that when hot Temps greater than 185, ase lasts longer. Ase can be calculated in either engine cycles or time. Determine which one you want to use and make ase last longer. Problem solved.
my initial ASE taper ended at 180 so I just changed the last 3 temp rows. This is what.it currently.looks.like
You've got afterstart enrichment (ase) and afterstart enrichment taper. Taper is the length, and ase is the fuel itself. Your ase taper looks to shape downward. Rather than change the temperatures, you can change the duration. For example you can make your 160 temp setting have a 300 duration, 175 a 350 duration and 190 and 400 duration.
You've got afterstart enrichment (ase) and afterstart enrichment taper. Taper is the length, and ase is the fuel itself. Your ase taper looks to shape downward. Rather than change the temperatures, you can change the duration. For example you can make your 160 temp setting have a 300 duration, 175 a 350 duration and 190 and 400 duration.
Your EGO is effectively off, since it has 0% authority. Use the authority table, set events to 32, set min rpm to 500, delay after start to 15, and make sure your authority table has a giant chunk of cells around idle that have 15% authority.
Your idle advance could use help too, but try the above first.
I don't know off hand how much is needed versus what I use. I went a bit overkill, but I also have idle ve active and I also have ego correction authority on too. I think mine is set to time based so my real one lasts for about 30 seconds or so after start. It is a bit richer than normal but then again ego correction masks it too. Ego correction I think is disabled for my car until 15 seconds after startup. That should compensate for the wideband not being instantly on at startup since mine needs some warmup time before it starts displaying a number.
You've got afterstart enrichment (ase) and afterstart enrichment taper. Taper is the length, and ase is the fuel itself. Your ase taper looks to shape downward. Rather than change the temperatures, you can change the duration. For example you can make your 160 temp setting have a 300 duration, 175 a 350 duration and 190 and 400 duration.
This strategy helped me also. Not perfect. Need to play with the curve more but the car is back to normal after driving for like 5-10 seconds so it really hasn't been an issue. You can make the tapper even high if needed so the graph looks like a V.
I don't know off hand how much is needed versus what I use. I went a bit overkill, but I also have idle ve active and I also have ego correction authority on too. I think mine is set to time based so my real one lasts for about 30 seconds or so after start. It is a bit richer than normal but then again ego correction masks it too. Ego correction I think is disabled for my car until 15 seconds after startup. That should compensate for the wideband not being instantly on at startup since mine needs some warmup time before it starts displaying a number.
That definitely helped. I have it up.to 500 at 190 degrees. Still has mid 15 afrs after.
on this should I have authority table ON? And controller authority at 15%? my.map.is based off diyautotune basemap and I watched the pedxing videos but other than using closed loop idle I haven't mess with the ego control before. Will turning this on help my hotstart issues?
Table on. 15% in idle area (I use 17%) moving to less in non-idle areas after your VE table is tuned. Then 5% around 100 kPa and 2% in boost... after VE, and MAT corrections are in place. Wider until then.
Table on. 15% in idle area (I use 17%) moving to less in non-idle areas after your VE table is tuned. Then 5% around 100 kPa and 2% in boost... after VE, and MAT corrections are in place. Wider until then.
OK. I set it up like that and started the car and it was worse than before. Clearly I have something messed up. Are yall using the PID algorithm on the afr/ego control?
I fixed this using only ASE. It's actually sitting between 5min and 40min or so that seems to be the worst. So I have ASE cranked way up from ~175f to ~145f (don't have my tune handy to check).
Okay, so I think I have it running better. I raised the ASE even more, and looked on diyautotune and they have an article on changes for better idling. I changed a few of the closed idle settings, and did some other changes to make my tune match some of the screens from trubokitty.com. According to diyautotune, batch fire engines like to idle a little richer than 14.7 so I lowered mine a bit and they also suggest to lower the timing some at idle and it can help. All and/or some of these have helped quite a bit.
I have attached my current tune and a datalog I just did at start up. Let me know what you guys think or if something in my tune looks way off.
Where to start... You have the turbo installed, I see. Wire the waste gate open until you have tuned VE table up to 100 kPa. Set Overboost Protection to about 110kPa. Then add boost a little at a time, moving the Overboost up with your tuning of VE.
Your 700 -1500 RPM Spark Advance are more aggressive than I usually see, but I don't know that it is bad, but I would use idle advance set lower at least.
Your VE table is a bit crazy.
Some hot restart tips:
1) Change ASE count units from Cycles to 0.1 Seconds. Your ASE is totally gone before your WB is even reading. For hot restart you need a lot of ASE until the EGO can come in, which it will not do until you are getting an AFR reading. Leave the ASE Taper about where you have it set, which will then end at 50 seconds, transferring the work to the EGO.
2) Add a LOT of ASE at the CLT you are working.
3) Add 7% (multiply by 1.07) your idle VE area. You are too lean down there.
4) Take out timing, best by using idle timing, down to about 12, and then make the RPM / idle advance curve more aggressive.
5) You have to turn on the EGO Authority table to use is. The left columns should not be zero.
Thanks for the tips. The VE table is set from me using VEAL several different times and that's where it has tuned everything to. I was wondering about the spark advance table but that is what came on the baseman from diyautotune.
04-26-2020, 04:27 PM
Hot start idle issues
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