Question about wideband fuel feeback tuning, and failsafes

ochizon · Post by **ochizon** » Mon Jan 16, 2006 3:13 pm

hello,

I do not have a megasquirt, but am seriously looking into getting one. First of all, I have a turbocharged 1996 tacoma, 2.4l engine. I am considering the megasquirt II, and noticed (according to the maunal) that I can use it along with my wideband controller to simply input afr values at given rpm/kpa cell, and let the processor do the rest. That is awesome! My only conern is if the wideband dies on me, and the tables are chasing a foul signal. Is there are failsafe to keep the engine from going crazy and blowing up in such a situation?

Also, unrelated, is there a boost controller function on the megasquirt II system?

Thanks

natesully · Post by **natesully** » Mon Jan 16, 2006 5:42 pm

I don't think there are any failsafes, other than not autotuning the "floor it" areas of your map. Since your truck is turbo, I would get a freind to drive while you tune the upper ranges by hand. As for the lower- the failsafe is that the tuning is slow, and there are limits to how "lumpy" it can make the map- it won't make mountains or valleys. Also, MS's autotune is on the laptop, not the unit, so you should know if it starts being stupid. When the laptop is off, it can only apply up to a 15% correction (or some other limits you set) and it is temporary, and the correction can be set to be only applied at low MAP, so it goes open loop when you floor it into boost.

For boost control- only MSnS-E, which runs on MS-I, has that feature. MS-II has more resolution, especially with regard to spark, but MSnS-E has more features than you can imagine.

jcorsaro · Post by **jcorsaro** » Mon Jan 16, 2006 5:46 pm

Yes you can set the limits of how much your wideband O2 can change the pulse width of the injectors. An ideal setting would be 10%, so the WB O2 controller can richen or lean the mixture within 10% of the set VE table.

ochizon · Post by **ochizon** » Mon Jan 16, 2006 8:27 pm

natesully wrote:I don't think there are any failsafes, other than not autotuning the "floor it" areas of your map. Since your truck is turbo, I would get a freind to drive while you tune the upper ranges by hand. As for the lower- the failsafe is that the tuning is slow, and there are limits to how "lumpy" it can make the map- it won't make mountains or valleys. Also, MS's autotune is on the laptop, not the unit, so you should know if it starts being stupid. When the laptop is off, it can only apply up to a 15% correction (or some other limits you set) and it is temporary, and the correction can be set to be only applied at low MAP, so it goes open loop when you floor it into boost.

For boost control- only MSnS-E, which runs on MS-I, has that feature. MS-II has more resolution, especially with regard to spark, but MSnS-E has more features than you can imagine.

Thanks guys.

So the msns-E is ONLY on squirt-I, but the higher resolution maps and IAC is on squirt-II?

Dang, thats a tough choice. I currently have a greddy type-s boost controller, so I can live without the boost control, but I would like to have the option down the road...

Is boost control for the squirt-II something that is down the pipeline???

keithmac · Post by **keithmac** » Sun Jan 22, 2006 3:47 am

The Latest MSNS-e contains some really good PWM IAC closed loop code.