LT1 $EE tuning for E10

[Terminal_Crazy]

Hi guys,
after losing my post I just typed out, I'll keep this brief.

What do I need to alter on $EE to go from E0 to E10 fuel.
Running 95 LT1 383 CL SD No MAF
My WB reads in AFR and the 12.8 target should be about 12.3 on E10. 0.96 correction factor for E10
Do I just increase the PE correction tables.

Anything else I should change like OL AFR target?


Also, how would i richen the cruise area. 1k-2k rpm 60-80 map.
VE tables just tune themselves back out.
Would raising the O2 swing voltages help here, By how much ?

TIA
Cheers
Mitch

[ralmo94]

Stioch for E10 is about 14.1:1,
100% gas 14.7:1
Wide band only reads lambda and represents it in AFR scale of 100% gas
The essiest way is to adjust commanded PE Afr to get desired reading on Wide band
Assuming already in tune.

Hope that makes sense

[Terminal_Crazy]

Stioch for E10 is about 14.1:1,
100% gas 14.7:1
Wide band only reads lambda and represents it in AFR scale of 100% gas
The essiest way is to adjust commanded PE Afr to get desired reading on Wide band
Assuming already in tune.

Hope that makes sense

Yeah, that's what i'm doing.

If it's running stoich on E0 the WB will be showing 14.7
If i then switch to E10, at stoich the WB will still read 14.7 yes?
At WOT I'd want to target 12.3 though.

What about the OL AFR Tables, would I scale those as well?

Thanks
Mitch

[ralmo94]

Yeah, that's what i'm doing.

If it's running stoich on E0 the WB will be showing 14.7
If i then switch to E10, at stoich the WB will still read 14.7 yes?



Correct. This is a subject that can be very complicated and confuse a lot of people, but it doesn't have to.
If you think of AFR as the recipe the computer uses to get the final lambda reading in the exhaust.
All oxygen sensors can read is the lambda of the exhaust. Stoich.
They don't read the the recipe that gets it that way. Lambda 1 is stoich. It is only expressed in AFR to be easily understood.
E10 stoich recipe is 14.1 = lambda 1
E0. Stoich recipe is 14.7 = lambda 1

I'm not familiar with EE, but the proper way to do it, is to change the stoich AFR value in the computer from 14.6 or 14.7 to 14.1.
But if the open loop tables still are referenced in AFR they still would need to be scaled as well.
To find what AFR is in lambda AFR divided by stoich AFR.
EXAMPLE
13afr divided by 14.7 stoich = 0.88 lambda
13afr divided by 14.1 stoich = 0.92 lambda

0.92 lambda multiplied by 14.7 stoich is 13.5 AFR.
So if you have a reading on the wideband of 13 AFR, the lambda is 0.88
The recipe to get it is different for different stoich fuels

So the easiest way, is adjusting the commanded AFR until you get the desired reading on the wideband,

Did I confuse anyone yet?

[steveo]

for E10 i just fudge the injector constant by 4-5% of enrichment. that'll cover everything.

[ralmo94]

for E10 i just fudge the injector constant by 4-5% of enrichment. that'll cover everything.

That sounds easy and quick :thumbsup:
Is the constant the lb per hr?

[steveo]

yeah. you can always scale the injector constant to add or subtract fuel everywhere at the same time. it is a pure base constant that all calculations use.

[Terminal_Crazy]

Many thanks Steveo.

[NomakeWan]

While we're on the subject, what exactly do the "AFR Target" tables do in $EE? We only have narrowband O2 sensors, so it can't be querying a wideband for precise AFRs. So what are these tables referencing as AFR?

[ralmo94]

While we're on the subject, what exactly do the "AFR Target" tables do in $EE? We only have narrowband O2 sensors, so it can't be querying a wideband for precise AFRs. So what are these tables referencing as AFR?

Not EE specific, but an open loop table is used when open loop. While open loop, the loop to the O2 sensor is not used, such as warm up, PE, Decel cut off, or O2 error. Some tunes have the table enabled during closed loop for sort of a lean cuise, anytime anything other than stoich is targeted, you are open loop

[NomakeWan]

Not EE specific, but an open loop table is used when open loop. While open loop, the loop to the O2 sensor is not used, such as warm up, PE, Decel cut off, or O2 error. Some tunes have the table enabled during closed loop for sort of a lean cuise, anytime anything other than stoich is targeted, you are open loop
Sure, but that doesn't answer the question. Without the ability to have any kind of precise AFR feedback, how is the PCM "targeting" a specific AFR? What is $EE using to determine AFR if not a lambda sensor?

[ralmo94]

Sure, but that doesn't answer the question. Without the ability to have any kind of precise AFR feedback, how is the PCM "targeting" a specific AFR? What is $EE using to determine AFR if not a lambda sensor?

That is what the VE table or MAF table is for, O2 is just for correction

[ralmo94]

To be more specific, fueling is based on airflow, how much air is going in the engine.
Knowing how much air is going in, the pcm can calculate how much fuel is needed.

The ratio is how many part of air to one part fuel
AFR

Air to Fuel Ratio
If we we are taking in so many lbs of air, we need so many lbs of fuel to mix the ratio.

Does that make sense?

[steveo]

Sure, but that doesn't answer the question. Without the ability to have any kind of precise AFR feedback, how is the PCM "targeting" a specific AFR? What is $EE using to determine AFR if not a lambda sensor?

most ecms work like this

1. you have an airflow measurement, either with a MAF or speed density (a volumetric efficiency map, in other words a chart that says 'in this condition the engine flows this much air')

2. you have the fuel flow metrics, that end up calculating something like 'if you open the injector for this long, this much fuel comes out'

3. you then try to hit your AFR target vs airflow vs injector metrics to figure out how much fuel to inject

this is both in open loop and closed loop.

there are auxiliary calculations like closed loop trims, transitional fuel needs like accel enrichment, and some other small calculations and constants, but those modify things in the above three steps. without step three, you aren't going anywhere.

in other words, without step three, how would you know that you don't inject one part air for one part fuel?

[ralmo94]

Good in depth simple explanation stevo. I hope he understands. :thumbsup:
I think there are a lot of people who think fuel control is from O2 sensor only.

[NomakeWan]

I don't think fuel control is from O2 sensors only; I'm just used to a completely different computer environment since I primarily worked with Japanese cars instead of American ones. Or rather, my Corvettes are the first American PCMs I've mucked with. In the Japanese world you have actual "fuel tables" that are set to deliver a certain amount of fuel for a specific load cell (RPM vs airflow). There is no "AFR Target" setting because the AFR will depend on how much fuel is put into any given load cell in the fuel map.

Now that steveo has explained that these PCMs don't use "fuel tables" in the traditional sense but rather have calibrations for airflow measurement, it makes a lot more sense. Thanks to both of you!

[ralmo94]

I'm glad you understand what you are adjusting, it's hard to do something you don't understand.

Just to be clear I didn't mean to insult your intelligence, and I'm sorry if you felt that way, I haven't seen a Japanese calibration that was setup the way you described, I can imagine I would e confused if I looked at one.

[NomakeWan]

I'm glad you understand what you are adjusting, it's hard to do something you don't understand.
Just to be clear I didn't mean to insult your intelligence, and I'm sorry if you felt that way, I haven't seen a Japanese calibration that was setup the way you described, I can imagine I would e confused if I looked at one.
No offense taken! Here's a calibration from a 1994 Skyline GT-R as reference.

17630
17631

It's in Japanese, but the adjustable values in the ECU are as follows:

K Constant: This is a catch-all constant that's used for all fuel calculations. It appears to function similarly to the "Injector constant" on $EE.
Injector Zero Time: Calculation for injector latency since larger injectors can 'lag' in response.
Feedback Switch: Set target temperature for closed loop transition.
Rev Limit: Self-explanatory.
Speed Limit: Stock JDM vehicles have a hard fuel cut at 180 km/h.
TTP Min/Max: Minimum and maximum injector pulsewidth vs RPM. This is usually used as a 'boost cut' for turbo vehicles.
AF_LIMIT: Not used.
Acceleration Enrichment: Self-explanatory.
VQ Map (not shown in above images): Voltage Quantifier. This is the table that converts MAF voltage into grams/second. It's the "MAF Calibration" table on $EE.
Fuel Table: Y-axis is RPM, X-axis is TP. "TP" or "Theoretical Pulse" is a calculated load value based on the K Constant and the VQ map. Each cell in the fuel table represents a TP index and an RPM. You change requested fuel based on where in the table you end up.

It wasn't until the R34 GT-R in 1999 that Nissan switched to using VE tables and doing things more "traditionally."

To further get your noggins joggin', here's the fuel data from a 1992 Subaru SVX:

17632

So yeah. I'd just never seen any of my tools used for 90s JDM cars refer to "Target AFR." It's always just fuel maps of load VS RPM. I can confirm that my buddy's 2005 Subaru Legacy uses target AFRs, for instance. I'm more of a 90s guy myself though.

Anyways, sorry for dragging this a bit off-topic, and again I really appreciate the discussion. It helps a lot!

EDIT: After staring at values for a while it occurs to me that these tables are probably actually AFR corrections. Target AFR is not a thing in any of the interfaces I'm familiar with, but if that means the ECU is always targeting 14.7, and thus the fuel tables are only mapping deviations from 14.7, then they make a lot of sense. Now I'm kind of impressed I was able to work with these things without figuring that part out. And it just makes me that much more impressed with how feature-rich $EE is for being a computer from 1994. Wild!

[steveo]

There is no "AFR Target" setting because the AFR will depend on how much fuel is put into any given load cell in the fuel map.

in other words, whether they integrate the AFR target into a table value or a separate value, it is always part of the math

[ralmo94]

voltage into grams/second. It's the "MAF

That is still airflow based,
The other table is what I believe is called ALPHA N fueling calculations, based off of throttle and rpm,
As far as I understood, early Subaru only used this for MAF failure, and rely heavily on MAF, unplug the MAF, no start
MAF failure, really rich, once the error code sets.
Although it occurs to me that a blending of some sort might be incorporated between alpha n and MAF.

To tune one of those, I would probably alter the MAF table to the required fueling.

Also, in the JDM ECU's just because you don't see it, doesn't mean it's not there, it may be just undefined, unless you have disassembled the code yourself and can confirm it's not there, but there should be a ratio somewhere in there, it's math, has to have it, may be eq ratio or lambda

[ralmo94]

Found a pretty though write up for different fueling modes explained, thought I'd share
https://forums.hybridz.org/topic/129546-alpha-n-maf-map-explained/

[NomakeWan]

Again, very helpful stuff. Thank you both for the knowledge!