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Old 03-01-2006, 05:28 PM   #1
Kha0S
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Question Odd closed loop behavior (AFR target)?

Car is a MY02 WRX running a modified A4SG900C ROM.

I seem to occasionally pick up some knock events at low RPM/throttle/load situations, ie, under cruise, that are causing the ECU to pull back IAM.



If you look, IAM gets pulled down to 14, then back up to 15. Load at/around the event is between 2600 and 2800 RPM, load around 2.05, throttle under 20%, around 1 psig of boost. Now, the ECU is (reasonably) in closed loop mode at that point, but my fuel map has a target AFR of around 13:1 at that load site:



But, looking at the AFR in the log, it's obviously still targeting stoich. Am I missing something? Does closed loop always target stoich, or should it be targeting the number in the fuel map for that load site?

/Andrew
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Old 03-01-2006, 05:39 PM   #2
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Closed loop will always target stoich. The front O2 sensor isn't really accurate for targeting much else according to most people.

You may be able to try adjusting the modified load switches in the CL/OL settings to see if you can get the car out of open loop easier. Else, maybe pulling a little bit of timing out of that spot will help?

Mike
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Old 03-01-2006, 05:43 PM   #3
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Gotcha. Didn't realize that CL was always a stoich target... ugh!

Mikie --- could I get your XML for 02 OL/CL tables? Doesn't matter what CalID, I'll find the right places in my 900C, I just need a baseline to know what I'm looking for.
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Old 02-12-2010, 02:25 PM   #4
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sorry for bumping this old thread but i figured id keep the closed loop info together.

is it possible to just change the target without having to rescale the maf or anything else. My current target is 14.47 and i want to target a leaner value of 14.7 during closed loop to see if i get a slight mpg bump.

thanks
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Old 02-12-2010, 05:54 PM   #5
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off topic, but what log viewer is that in the OP?
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Old 02-12-2010, 08:32 PM   #6
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Quote:
Originally Posted by scoobystas View Post
sorry for bumping this old thread but i figured id keep the closed loop info together.

is it possible to just change the target without having to rescale the maf or anything else. My current target is 14.47 and i want to target a leaner value of 14.7 during closed loop to see if i get a slight mpg bump.

thanks

Should be able to. Stock ROM is set to 14.7, at least mine is.

The question is why yours is set to 14.47? Perhaps someone slipped when intending to type 14.7? I can't really think why someone would use a closed loop target lower than 14.7 unless they didn't know how to program the CL / OL delay tables.
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Old 02-12-2010, 11:36 PM   #7
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its a jdm rom and all others that i've looked through (s202, 03 stock sti, 05ra, 06ra) are set to 14.47. The targets in open loop under low throttle and low load (basically upper left hand corner) is all set to 14.7.
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Old 02-13-2010, 03:12 AM   #8
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this is a stock usdm 03 wrx rom. Unless i'm looking at this the wrong way or this is the wrong table, it also targets 14.47 for closed loop A/F ratio.

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Old 02-13-2010, 06:02 PM   #9
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bump.
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Old 02-13-2010, 06:03 PM   #10
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Yep, I was wrong, mine is 14.47. Sorry about that.

Running leaner will increase EGT some and also NOX emissions (but reduce hydrocarbon emissions)

As long as those are fine, you should be okay changing this.
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Old 02-17-2010, 11:07 PM   #11
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Quote:
Originally Posted by scoobystas View Post
this is a stock usdm 03 wrx rom. Unless i'm looking at this the wrong way or this is the wrong table, it also targets 14.47 for closed loop A/F ratio.
I think there may be more to it than that...

What's in the "CL Fueling Target Compensation (Load)" table?

Can you post a screenshot of it?

(You can see that table in the list on the left in the picture you posted.)
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Old 02-18-2010, 01:12 AM   #12
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Old 02-18-2010, 02:30 AM   #13
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OK, so that's actually not very interesting.
Just .3 richer at low RPM and .1 richer everywhere else...

Thanks, though!
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Old 02-18-2010, 09:13 AM   #14
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So if the load compensation makes. It even richer, than the real target is 14 .1 at idle?
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Old 06-27-2010, 02:37 AM   #15
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This comp table makes afr richer to make it easier to move to OL right? Idling and low end/rpm wouldnt need to be richer.
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Old 06-27-2010, 09:35 AM   #16
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the cl target load comp for standard units is a simple adder to the AFR - so it would be leaner not richer. So, 14.47 + 0.111 = 14.58:1.
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Old 06-28-2010, 06:08 AM   #17
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^^^^ thats what i figured, its a compensation thats removing fuel and allowing the car to run leaner. I basically just determined that by watching my stock A/F sensor which is always showing much leaner than 14.1, a value that would targeted if those compensations where adding fuel (14.47 - .303 = 14.1).

i think the thing that throws people here is that adding fuel is actually a subtracting a value....as per small equation above.
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Old 06-28-2010, 10:00 AM   #18
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Te help prevent any confusion here, putting a positive number in the CL Fueling Compensation Table (Load) makes the car leaner. Putting a negative number makes it richer.
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