Dus10

Just wondering of there's a way to control the closed-loop afr's?

evo8dad

iTrader: (15)

What would be the benefit of doing so, other than better fuel mileage? Just curious, sorry to pirate and not answer the question, although I do remember reading somewhere in here that it is possible.

cpoevo

iTrader: (1)

I would like to know so I can pass smog.

Dominos

Closed loop control? What exactly do you mean? Why wouldn't you pass if the car is in closed loop. Give us an example and we can help.

MalibuJack

iTrader: (5)

Well, there are settings for AFR Target in closed loop, only we haven't found them yet.

But the truth is, there is no reason to really adjust it. Typically if the AFR's arent 14.7 it has to do with trims being out of an adjustable range.

However, we will find this setting as more of the ECU's rom is disassembled.

Kyle_Y

found it

15 cell target map ..

I'm being a tease now !!

MalibuJack

iTrader: (5)

Sharing is caring.. LOL

Dus10

Okay, school the newbie time...
Everyone keeps posting that anything higher than 12 AFR is way to high, but in closed loop the car runs 14.7 and if your not boosting it will run those same afrs in 6th gear @ 5Krpms cruising along with no boost. So... It's okay to run 14.7 as long as your not on boost?

what makes too lean a mixture bad? Is it heat or knock or something else?

Also, is the max amount of boost you can run dependent on internal mods or is it strictly concerned with knock? So... if you could run 24psi w/ no knock on a stock motor, is that okay, or is there another reason not to run that much boost ?

mchuang

iTrader: (11)

14.7 is stoich for gasoline and normally your target cruise and idle afr in close loop give or take a few unless you got some huge injectors then if that is the case it is sometimes hard to get them to idle at 14.7. Once your car passes somewhere around 33% throttle range the ecu switches to open loop which is what you tune under 12.0. Most street cars tune to about 11.0 to provide a safety net just incase variables get to out of the ordinary. Heat and knock are both related because 1 causes the other and lean causes them both inside your cylinders. On pump the max you wanna run most people say is about 23psi on pump. On race gas you can run 30psi if you want, but some people suggest getting arp studs to reduce the risk of headgasket failure due to headlift.

Dominos

Isn't the low and hi octane fuel maps the target maps?
Why would they give them an A/F target then?

l2r99gst

iTrader: (2)

Those are the open-loop fueling maps. The question in this thread is about closed-loop fueling.

Eric

nj1266

iTrader: (6)

The only reason to do this is to improve gas mileage. I have done it using my LM-1, but I did not really test the results even though I said I would. Here is how to do it if you have an LM-1

https://www.evolutionm.net/forums/sh...67&postcount=3

Dominos

I was under the impression that the ECU had only one commanded A/F target map.
Regardless of open or closed loop. The closed loop function or map, I am guessing, would only have a predetermined stoich target. Not really a map. Are you trying to command a leaner cruise condition? With a narrowband it isn't very reliable. All you have to do is kick the ecu into constant open loop. Very simple. And then work with the map you have. It will still use the modifiers and scalers in the background right? Makes sense to me.

Dominos

If your fuel trims are are low then you are really not going to get any town mileage. Even still I don't know how you are going to command a leaner than 14.7 A/F.
If you really want control of all the fueling, then shut down the closed loop function all together. Run it off the base map

MalibuJack

iTrader: (5)

AN old trick back in the day of early closed loop was to alter the signal from the O2 sensor, that forces the target AFR to shift...

This really isn't necessary anymore, There **IS** a different table for closed loop target, I think its a single row of values from idle to redline.. I heard someone had actually found it, but has chosen not to share.

I think one of the guys working on the rom on my website (Aktivematrix) may have this info, and I have asked for the info a few days ago. So its possible it may come together. I asked for a few items specific to these adjustments so it may take him some time.

Basically I was looking for all of the injector scaling and closed loop fuel target tables since those are the areas we don't currently have enough data on (or adjustment)