I'm not sure how you produced that chart but I wouldn't go off that at all. I've seen .89 with 12.5 AFR, 12.0 AFR and 11.8 AFR, .92 with 12.1 AFR, .94 with 12.5 AFR. .92 with 11.0 and 10.8

Yes we "all" used narrowband to tune at one point in time, however now that widebands are so cheap, if you are at all into learning and tuning your own car, I would urge people to buy a wideband.

-Bryan

 

The only thing this proves, is that you can get the o2 reading to be the same throughout a pull, it doesn't say a lot, really, about the actual AFR, other than that there are no extreme peaks or dips.

If things are set up right, your fuel map and actual AFR should be reasonably close, but without using a wideband at some point in the tuning process ... the best you can do is get your trims right on, and hope it's "close enough".

 

sigh ... it's my engine and I can blow it up if I want to ...

So how about actually helping me with the question I asked, namely how to change the set point where the ECU changes from closed to open loop?

 

Yes you can. You can also help it make less power if you want to. (again, not trying to be a dick, just trying to be clear about things)
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You answered the question yourself. I believe it needs to meet both conditions of throttle and load to work correctly.

The secondary tables are probably for some switchover point similar to the switchover point for gear dependent boost control... maybe even the same one. If you want to be on the sure that your setting takes set them both to the same thing.

Any particular reason you want to change the switchover?

 

Using tables that are named "Open Loop..." ...

 

I noticed that "Open Loop Load #1" and "Open Loop Load #2" had different values in my ROM, and was trying to understand why. Also trying to learn what the "14.7" in the AFRMAP is good for - if the ECU never reads that cell could it be any value (like zero?) without it making any difference?

The "Open Loop Throttle Table" has RPM in the left column but ranges 0-3 in the right column, so I didn't understand what they represent. For TPS I would expect different values ... I've attached the tables so you can see what I mean.

 

The 14.7 is there kind of for a holding place to keep the stoich plateau open. Since the car operates in closed loop with the stock open loop load tables...it won't even be looking at the fuel map, it will be calculating everything from the o2 sensor.

Not sure if anything would change if you put 0s in the plateau.

 

I'm guessing the TPS tables are voltage, have you checked what scaling is set to them? You can change that to percentage if that is the case.

I thought that the 14.7 (rather the area in the closed loop curve) was used as a check-back for the closed loop fuel control, but that may have been defunct.

 

You can't change the 14.7's to 0's. When you start your car, it starts in open loop until several conditions are met, such as a certain coolant temp, etc.

 

Once you run the car in open loop via those tables and fuel map, you will understand more how the narrowband sensor loses resolution and accuracy the further away from Stoich it goes.

- Bryan

 

I think you may have just lost any reliable tuner input with the hillbilly O2 logic you posted. And dont get me started with using EGT as a tuning tool... you will have better luck using astrology to tune than a narrow band sensor and an EGT meter! Maybe some magets will also help.

 

You're right they are in Volts - I didn't notice the lonely little "V" in the units box .

I think that may be the right answer, it makes sense that the ECU runs open loop until the car is warmed up and needs something to target even while in the closed-loop region of the map. However, if that's true that tells me I need to change the 14.7 region just like any other part of the map after changing injectors - otherwise the AFR will be off while warming up (before going into closed-loop)?

Common "EvoM wisdom" is that this region does not need changing, but you know me ... I question everything . This could explain some of the cold start problems people are having with larger injectors (myself included). I'll do some experimenting when I get the chance and let you know what happens.

 

If your scaling and latency changes are correct, then you should not have to change any part of the fuel map to run the same AFR you where running pre injector upgrade, closed loop or open loop.

- Bryan

 

okay now I'm really confused ... I have been following the instructions in the "How to tune an Evo" thread. The way I understood it, I installed the injectors (PTE780) and then logged my long term fuel trims (using Mitsulogger) to find the correct injector scaling and latencies. I ended up with a scaling of 696 and the latencies in the attached table. These give me LTFT low (idle) of -1 and LTFT mid (cruise) of 0, verified after several 15 min intervals of idling and cruising. Reading on, it said in the thread:

But from what Bryan said above, it sounds like it is not necessary to retune the AFR map once I have the right values for scaling & latency (as verified by LTFTs).

At this point I'm convinced that if the map needs changing, then all of it needs to be changed (including the closed loop 14.7 block); however, if having near zero LTFTs is what you mean as "correct" scaling/latency changes, then none of the map should need changing at all. So which one is it

 

Bryan is correct. If the injectors were scaled properly, your map shouldn't need any changes.