Closed Loop calculated Load

[prana]

What is the precise criteria that makes this value in memory ? 0-255 max

I am trying to run my wrx in closed loop below 2400rpm continuously. But although the throttle value is set to >100%, it keeps falling out of closed loop and into OL. I suspect the table above "Closed Loop Calculated Load" may have something to do with it. The stock value is 80, I set it at various values, 88, 100, 200, 255

Maxxing it out (at 255) causes the vehicle to run VERY much in open loop even in idle and is very unsettled. Running at 200 is no good either, and I want the closed loop functionality.

The description clearly states "when modified load rises above these values... enter open loop" so how can we bypass this and make it remain in closed loop, quite the contrary or I've misunderstood the description above ?

[Freon]

There are literally dozens of tables that determine closed loop operation. I'm not sure you're going to have much luck.

Generally when people discuss closed loop is just closed loop fueling, and certainly, whether you realize or not, this is what you're talking about. Why do you want to keep it in closed loop under 2400rpm? What is your actual goal? What is the problem with slipping into open loop?

If you want, you can just put an AFR of 14.7 in ever spot in your fuel map below 2400rpm. This will have almost the same effect. The only difference is that in open loop your fuel trims will not move. It doesn't mean you shouldn't be able to tune pretty close to 14.7:1.

[prana]

Hey Freon

Yeah I want to keep it in closed loop below 2400 revs regardless of throttle position. Right now, I have a great tune under 2400 revs based on the open loop but I'm experimenting with the effects of CL.

So there is no way from these tables, to force fueling into CL at all load ranges and throttle positions under 2400revs ? As I know EXACTLY what fuel AFR I want - and I want to achieve that with every fuel (some fuels differ by 0.7:1 actual afr)

On a seperate note, I put the CL TPS to 100.1% (cause thats the value it accepts) and Calculated load to anywhere between 200-255, the idle started hunting, and was weak off the line as it couldnt stabilise, as if there were some issues with oscilation. Perhaps this caused the feedback loop to go into oscillative state ....

[Freon]

Closed loop is always shooting for 1.0 lambda, no matter what is in your fuel map. From what you're saying I'm guessing you didn't realize that. You cannot run, say, 14.0:1 or 13.5:1 in closed loop. It ignores your fuel enrichment map.

Your best bet to hit a certain AFR target is careful calibration of your MAF scaling. That seems to be your end goal, not staying in closed loop. I think you have mistakenly decided staying in closed loop is the way you are going to reach your penultimate goal of hitting a very specific AFR. I do not believe this is true.

The car uses long term trim to adjust for differences in fuel. If you change fuel, that difference in chemistry should show up in long term trim. This long term trim is applied to open loop fueling, thus you should see your AFR consistent at the same load and rpm if you are well tuned. It's going to adjust everything so it reads lambda 1.0 in the WB02 in the front exhaust manifold. It does not take long. Usually you'll see after an ECU reset the long term fuel trim slowly move to a certain level, then not vary much. Same goes for switching fuel. You should see it move and settle at a certain level after driving a few miles.

You really should be able to get open loop fueling to hit a pretty consistent AFR. It's not going to be perfect, but it given how many compensations are available you should be able to work it out in the long run via the tune.

[prana]

Freon - big thank you, great post.

I did manage to get a consistent 12.54 where I have set it to 12.54 but under very light throttle, but I'm guessing this may be more fluke than anything fom its learning (perhaps I did decide upon the best afr) and the ecu decided the same lol . Appreciate the time you have taken to explain in detail - very very good reading.