Thread: Formula to get air/fuel ratio?

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2012-08-31 18:20:32

#21

Vadim

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Sounds good, I need update may Calum tuning guide with that info too then.

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2012-08-31 19:28:51

#22

blo0d

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Originally Posted by Vadim

Originally Posted by dfddfd2

Yes it matters because those values adjust the AFR when in open loop, like during warm up, and during closed loop to keep the AFR near 14.7 as to keep the closed loop control system within range. Even though the fuel map values indicate closed loop (greater than or equal 128), closed loop doesn't start until a certain CLT is reached and the throttle is fairly steady. And yes, 200 is about 6% increase in IPW than 192.

Dave

I thought timing feedback was 128 or greater and fuel was 192 or greater. Though I do have plenty of 180's (even OEM tunes do too), which is more like -12.

With my current K value and injector size, I'm hitting more then 100 values in my WOT areas, so if I set those to 128 by accident it will lean it out? If so might need to adjust the K value way down

so what percent of IPW is 180? Im a little confused about values in the fuel map below 192. I have never really seen it in a stock map

and for reference what is the percentage of IPW is 5 in the fuel map... well dave answered that 0-127...

Last edited by blo0d on 2012-08-31 at 19-40-38.

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2012-08-31 20:01:56

#23

OnTheChip

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Originally Posted by blo0d

so what percent of IPW is 180? Im a little confused about values in the fuel map below 192. I have never really seen it in a stock map

and for reference what is the percentage of IPW is 5 in the fuel map... well dave answered that 0-127...

It's all explained in the TunerCode documentation.

Dave

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2012-08-31 21:36:09

#24

blo0d

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Originally Posted by dfddfd2

Originally Posted by blo0d
so what percent of IPW is 180? Im a little confused about values in the fuel map below 192. I have never really seen it in a stock map

and for reference what is the percentage of IPW is 5 in the fuel map... well dave answered that 0-127...

It's all explained in the TunerCode documentation.

Dave

lol dunno how i missed the fuelmapcoef document... my bad

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2012-08-31 23:33:30

#25

Haulin200sx Online/offline status of Haulin200sx is unknown

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This is all great info guys!

BTW i only wanted to know this because i myself find it easier to tune the fuel map when its view as air fuel numbers. This is just my personal prefrence lol.

example:

Goal is 13.0:1 AFR at a givin RPM.

Let's say im running 14.0:1 at that RPM. If my fuel map says 13.0:1,then that tells me i will need to run about 12.0:1 AFR to achive my goal. I find its easier to get the tune closer right off the bat or would only take a few tries to get your achived AFR. This is all on a basic chipped ecu also. I do not have a realtime ecu. So burning chips a million times is annoying lol. I can not just simply subtract a bit of fuel easily with the engine running to get to my goal.

I know this conversion formula is just a rough guess and doesnt mean anything. I do find though that the closer you have your tune to being perfect that these theoretical air fuel numbers almost match your goal air fuel. If not i feel you are off because your Constant/latency etc is off. Im not saying this is true. This is just my experience.

Last edited by Haulin200sx on 2012-09-20 at 21-04-26.

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2012-09-20 20:45:13

#26

blo0d

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guys... i have another question. if there is no O2 sensor connected, will the TTIF coef's in closed loop (128-255) still be applied?

Im intrigued with how small we can get the TTIF in closed loop and how open loop doesnt have such translations.

Last edited by blo0d on 2012-09-20 at 20-45-56.

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2012-09-20 21:22:47

#27

OnTheChip

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Originally Posted by blo0d

The TTIF coef's from the fuel map values are always applied, open or closed loop. Disconnecting the O2 sensor without disabling closed loop will cause the O2 sensor DTC to be set.

The closed loop fuel map values should be set for 14.7 AFR in open loop to minimize STFT and LTFT. The open loop fuel map values should only be needed to enrich AFR and therefore have a higher coefficient range.

Dave

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2012-09-20 22:46:43

#28

blo0d

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Originally Posted by dfddfd2

Originally Posted by blo0d
guys... i have another question. if there is no O2 sensor connected, will the TTIF coef's in closed loop (128-255) still be applied?

Im intrigued with how small we can get the TTIF in closed loop and how open loop doesnt have such translations.

The TTIF coef's from the fuel map values are always applied, open or closed loop. Disconnecting the O2 sensor without disabling closed loop will cause the O2 sensor DTC to be set.

The closed loop fuel map values should be set for 14.7 AFR in open loop to minimize STFT and LTFT. The open loop fuel map values should only be needed to enrich AFR and therefore have a higher coefficient range.

Dave

Dave, thanks for the response... translate STFT and LTFT please... lol

but just to be clear... if there is no O2 sensor connected, and I wanted to achieve a TTIF of 2048... I can still input 128 in my fuel map... correct?

Last edited by blo0d on 2012-09-20 at 22-48-45.

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2012-09-20 23:02:13

#29

OnTheChip

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Originally Posted by blo0d

Sorry about that, LTFT and STFT are terms used in Nismotronic.
STFT=Short Term Fuel Trim or "Closed Loop TI Factor"
LTFT=Long Term Fuel Trim or "Long Term Fuel Trim Factor"

Yes, you can use 128 in the fuel map.

Dave

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