lean @ idle after 30 min heat soak

[LDR]

After the car has sit for 30 minutes after driving at running temp. The restart is lean until intake temp comes back down.

[keithmac]

Common problem, the intake temp sensor may not be showing actual temp at that point due to engine bay heat warming the sensor up (among other reasons).

Heatsoak is a problem on all systems not just MS, some OEM's run a timer in the ecu from last start and strategies to combat lean running on restart.

[nathaninwa]

It could also be that the ideal gas law doesn't work in real life and to much fuel is being pulled from the air density table at that 130* temp your at, all that depends on what temp the fuel table was tuned on initially, or the last auto tune session

It took me all four seasons to get my density table to be within 4% year round

[Hahns5.2]

Injector dead-time plays a big role too. It looks like you're using the default value. Getting that figured out and tweaking the MAT correction table should help a lot.

[racingmini_mtl]

It could also be that the ideal gas law doesn't work in real life ...

I'm sorry but this is the same as saying that gravity does not work in real life. The issue is that you are not measuring the correct value for one (or more) parameter of the equation (most likely temperature) not that the actual physical law and its equation is not valid.

Jean

[nathaninwa]

I completely understand Jean. I have 3 installs of known dead time (understandably not from megasquirts drivers but a correct curve anyhow) and 5 other friends that are using the curve I created on my DD turbo car and all setups have minimum ego correction in a wide temperature range

So maybe to say it's not so ideal is wrong, but I have found it seams to aggressive

[LDR]

I started messing with the MAT table yesterday and seems to be helping a little. I was told not to mess with injector dead time unless I knew what injector I had and the specific dead time the manufacturer wanted them run at. They are what ever GM used in their tuned port 350 engines. I think they are 21lbh. I done some wot logging yesterday and noticed the duty cycle on them was over a 100% at the initial hit of the throttle. Then between 5300 to 5500 they are in the 90% range. The engine is still a bit rich will that affect this? Or are they to small? The engine is stock with no power adders of any kind. Will keeping ASE on longer help this? It seem pretty good until that shuts off. I read you could change the ASE from cycles the seconds but haven't found the tab for that yet. Thanks

[nathaninwa]

Did you borrow tune from someone? There is some things that need addressed from a quick glance this morning

Your ve table Gos extremely high after about 6000, I realize the tuned port might not rev this high and maybe you were concentrating on the lower cells

Your timing flatlines at 19*

And a motor of that vintage ran a little leaner than the target your after in the afr table. Usually it was around 13.0 to 13.5 afr, but it's best to find a dyno to figure that out

Did you register your TS and have access to VEAL? Change some of your ego settings and as long as the wideband and TS match then I would let auto tune start to smooth the ve table out and I bet your DC starts to some down some

[LDR]

I know the VE table is high up their, it was like that at 3500 and above. I'm work it down slowly. What needs changed on the ego settings? The wide band and TS are pretty close. I can auto tune always seemed worse when it was done. Probably have something set wrong.

[hoveringuy]

I took some measurements a few years ago and found that my injector coil resistance went up when they were heat soaked. From around 13.5ohms to 16ohms, as I recall. I never proved that the increased resistance resulted in longer dead times (less amperage, right?). But I always felt that it was fuel flow after the hot start that cooled them back down and fixed mixture.

[keithmac]

How long does it take to come back to "normal" after a hot restart?. Maybe run a timer and some additional enrichment if car is started with IAT or coolant over a certain threshold?.

My Mitsubishi cam with a solenoid that opens the Fuel Pressure Regulator mainfold reference line to atmosphere on hot restarts to combat the lean restart issue, they mush have deemed that method better than trying to write the solition into the ECU code?.

[DaveEFI]

Injector dead-time plays a big role too. It looks like you're using the default value. Getting that figured out and tweaking the MAT correction table should help a lot.

I'd give a plus one to that. My car suffered badly from what seemed to be heat soak after parked up hot. Had to open the throttle to get it to start at all. It then ran badly for a short while things equalised. Yet you could get it as hot as you wanted, and it would idle perfectly. So not something that demanded immediate action.

Playing with the IAT correction helped a bit - but isn't easy to do as things change so quickly. Going back to basics with injector dead time made the biggest difference. (My injectors are early low impedance types, and I never found data on what the dead time was)

[LDR]

OK, I'm going to start playing with the dead time on the injectors. I drove the car 400 miles this weekend, it averaged 20 mpg so I don't feel driving tune is far off. I'm sure it can be tweaked some more. If I can get this restart fixed it will be perfect. Do I increase or decrease dead time? Is this change going to change fuel table?