Has anyone found a charge temp solution?

[Higgs Boson]

If it moves more slowly at idle both ways I still don't see how that's worse than reading 40 degrees hotter than it should..... Once you get moving you aren't using the same filter cells anyways so it will still adapt quickly everywhere else, right?

[redhardsupra]

The setup SoundEngineer posted is conceptually flawed. You're using airflow as one of the inputs to the function that determines BIAS, thus TEMP, thus airmass, thus airflow again. That's circular reasoning, and that does not make much sense, is it?

And that's not the only flaw. SE's histogram attributes ALL errors to ONE table, this time it's BIAS, instead of IFR, PE, MAF, VE or whatever else all the hacks of the past have used to 'tune'. All these measurements come with noise, they contribute to the overall noise, so why blame it all on one table?

The histogram is not set up right either, because it simply isn't made to handle enough dimensions. SE has IAT, airflow for the independent values, and Lambda for the dependent value. What happened to ECT? If it's a part of the function, then it needs to get back in there, doesn't it? Oh wait, you can't make a 4D histogram in HPT, it's not made for such things.

I have a strange love-hate relationship with all things AFR%error based. On one side it's great to have, it's a simple, yet 'reliable enough' metric to assess the correctness of airflow estimation. It has helped us tune, it took us out of the dark ages of tuning where you just make changes and hope for better results without an objective metric of the results f the changes we've made.

On the other hand, once we got this one tool and now we try to use it for everything. There's a saying that 'if the only tool you got is a hammer, then everything starts to look like a nail' which I think is exactly what's happening here. Don't overuse it. It is clearly not the right tool for the job here. Add a new tool to the repertoire, don't just try to cram a round peg in a square hole.

[S2H]

The setup SoundEngineer posted is conceptually flawed. You're using airflow as one of the inputs to the function that determines BIAS, thus TEMP, thus airmass, thus airflow again. That's circular reasoning, and that does not make much sense, is it?

And that's not the only flaw. SE's histogram attributes ALL errors to ONE table, this time it's BIAS, instead of IFR, PE, MAF, VE or whatever else all the hacks of the past have used to 'tune'. All these measurements come with noise, they contribute to the overall noise, so why blame it all on one table?

The histogram is not set up right either, because it simply isn't made to handle enough dimensions. SE has IAT, airflow for the independent values, and Lambda for the dependent value. What happened to ECT? If it's a part of the function, then it needs to get back in there, doesn't it? Oh wait, you can't make a 4D histogram in HPT, it's not made for such things.

I have a strange love-hate relationship with all things AFR%error based. On one side it's great to have, it's a simple, yet 'reliable enough' metric to assess the correctness of airflow estimation. It has helped us tune, it took us out of the dark ages of tuning where you just make changes and hope for better results without an objective metric of the results f the changes we've made.

On the other hand, once we got this one tool and now we try to use it for everything. There's a saying that 'if the only tool you got is a hammer, then everything starts to look like a nail' which I think is exactly what's happening here. Don't overuse it. It is clearly not the right tool for the job here. Add a new tool to the repertoire, don't just try to cram a round peg in a square hole.

you are looking at the bias the way it should be... not the way it is in an ls1 pcm.

unfortunately there no fueling tables to correct for IAT differences..except for the Bias table...which unfortunately is the only table that changes teh fueling based on your airflow and IAT.

we provision for the ECT portion of the the bias by making sure we only collect data from full operating temperatures where the ECT swing is very minimal...

tuning for the ECT changes we use the OLFA table.
you could say the exact same thing about it that you say about the bias...where is the IAT provision for the OLFA table?

unfortunately GM didnt provision for a 4d style table like the newer pcms have by using several 2d tables to work together to create a 4d table

now...all of this said.. I do appreciate your input Red... but this table is the best option for the problem at hand...

as an experiment I moved my IAT to the bumper...getting it out of the engine bay heatsoak environment...
it helps noticeably with the fueling...but it still doesnt quite fix the problem completely...
I still had to play with the Bias table(from the stock values) to get it to react better to increases and decreases in IAT.

I was able to figure out that the bias table needs to be adjusted based on a percentage(atleast on my car)
in 77* temps in the early AM hours, I was able to see my fueling at just a hair lean in open loop.. later that day.,..in the middle of the day..seeing 98* air temperature, it was lean(airflow based) compared to the earlier values
my lower values were 15% different, and as the airflow increased the variance was less and less...
I increased the bias table...more where it was leaner, less for the less lean areas.

My stock table

0.79980    0.41992    0.28271    0.24365    0.21973    0.20264    0.18848    0.17578    0.16455    0.15381    0.14355    0.13428    0.12451    0.11523    0.10645    0.08984

my new table

1.00000    0.70020    0.50000    0.37500    0.28564    0.20264    0.18848    0.17578    0.16455    0.15381    0.14355    0.13428    0.12451    0.11523    0.10645    0.08984

my results came out pretty darn good. the next day...with similar morning and afternoon temperatures I saw only a 2%~4% difference in fueling
I have been doing double checks on it now for several days and various temps...it seems to be very stable.
stable enough that I dont feel the need to change it any more at the moment.

I havent had to mess with the upper airflows

I'm hoping to be able to have the patience to do a write up if I have the time and motivation to do so.


*the biggest help was getting the IAT out of my engine bay.. I still needed to change the bias, but it wasnt as radical as when my IAT was still in the engine bay.*


and granted, this was only 20* of temperature difference...but I was seeing large fueling differences on those 20* temperature changes and now I'm not


I plan on checking it as the temperatures change to see what happens.

[bseitz]

Scott,
Could you post up your "Bias Table" numbers before you moved the IAT sensor out of the engine bay?

Thank you for all the great information that you have shared here.

[WS6Fury]

I'd be curious to see as well, and would like to know if you are running a larger lid, tb and intake (ie 90mm), cam etc just to get a relashionship of changes you had to account for. Since something like this would slow the air flow at low rpm, and at idle the IAT will get soaked a bit faster from radiant heat plus pulling in heated engine bay air.

I am really intrigued by the relocation of IAT method though. I assume the IAT is not weather proof since it has an exposed element correct? I'm curious if it is weather proof, then it would open up many areas to direct air flow. If not weather proof, I haven't the foggiest clue where else to relocate so that would both protect from water (esp in a hard rain) and still have air flow.

[Higgs Boson]

I just checked my avg AF ratio in 70 vs 90 iat avg temp and with the stock bias table it was 2.7% leaner at 90. I see no reason to deviate from stock anymore. My maf is removed however and my iat sensor is in the intake tube ahead of the radiator so technically out of the engine bay.

[S2H]

this was my bias for my vehicle with the IAT Sensor being located in the intake where the EGR would normally connect at(directly behind the TB opening...IN THE FAST INTAKE!)

1.29980    1.20020    0.75000    0.54395    0.45996    0.44043    0.43164    0.42285    0.41406    0.40625    0.39746    0.38867    0.38672    0.37988    0.37988    0.37988

this would not work on every vehicle...
My mods (for Now) are
2001 Camaro z28 M6 stock LS1 Block and rotating assembly
LS6 PCV conversion
98mm Lid
K&n Filter
No MAF
No Air Pump, No EGR
4" custom tubing between Lid and TB
92mm Nick Williams TB
92mm FAST intake
Custom Grind Cam with EPS Lobes 234/242 .601/.605 111LSA+2
Manley Dual Springs with titanium retainers
Stock Rocker with Trunion Upgrade
Stock 241 Heads
Stainless 1-7/8 Kooks Longtube Headers to 3" collector
stainless Kooks 3" Catted Y Pipe
3" stainless Magnaflow Catback with dual outlet
Tuned by ME

[WS6Fury]

Wow very similar to mine, less the cam and heads. Your cam is a tad bit bigger than mine, the head I got are etp 215's.

Looks like the curve is the same type as stock though which is good to know, and the lower end of the bias table definitely gets higher it looks since our airflow inlet speed is slower in the lower rpm range.

And I didn't know you can attached a scrolling chart like that, pretty cool!!

[S2H]

use {code}stuff in the window{/code} replace the {} with regular brackets[]

[bseitz]

this was my bias for my vehicle with the IAT Sensor being located in the intake where the EGR would normally connect at(directly behind the TB opening...IN THE FAST INTAKE!)

1.29980    1.20020    0.75000    0.54395    0.45996    0.44043    0.43164    0.42285    0.41406    0.40625    0.39746    0.38867    0.38672    0.37988    0.37988    0.37988

this would not work on every vehicle...
My mods (for Now) are
2001 Camaro z28 M6 stock LS1 Block and rotating assembly
LS6 PCV conversion
98mm Lid
K&n Filter
No MAF
No Air Pump, No EGR
4" custom tubing between Lid and TB
92mm Nick Williams TB
92mm FAST intake
Custom Grind Cam with EPS Lobes 234/242 .601/.605 111LSA+2
Manley Dual Springs with titanium retainers
Stock Rocker with Trunion Upgrade
Stock 241 Heads
Stainless 1-7/8 Kooks Longtube Headers to 3" collector
stainless Kooks 3" Catted Y Pipe
3" stainless Magnaflow Catback with dual outlet
Tuned by ME

What temp. thermostat are you running?

With the hot summers and cool winters and the large swings in outside temps here in AZ I'm thinking I might also need to run a warmer t-stat. I would really hate to do that though.
I'm thinking that a more constant ECT would also help.

[S2H]

I run the stock thermostat.. 160* t-stat is a croc of crap if you ask me...
no matter what t-stat you put in... our LS Engines like to be at about 200~210 * for best power.
not only that..but if you run your car normally..it will eventually get to about that temp anyways... doesnt matter where I set my fans at...and if it did go back down that low in temp...then you would be hosing yourself for the fuelilng changes and you are just asking for an inconsistent vehicle.

there is no point to the 160* thermostat

[bseitz]

That's what I'm thinking. I'm not finding one Bias Table that "fits all" here.

On a 110* - 115* summer day the ECT can get up to 192*- 195* ish and the IAT's are 3*-5* over ambient cruzing at 75mph on the freeways. Temps drop down some around town but IAT's go up.

In Winter on a 65* day ECT will stay at 174*. Oil temp around 190-195.

[SSlow99]

I don't mean to jack this thread or anything and I'm usually one to keep my mouth shut and ears open.

All I do is bracket race my car period. Now that Fall is getting near and temperatures will vary from 90-100 in the day and low 60s at night what can I do to keep my car more consistent?

I've built a SUX2BU style ram air and I located my IAT in the tube. It doesn't heat soak or anything, but the temperatures change here drastically going from day to night.

Will changing the bias to 1.00 meaning it's 50/50 IAT and ECT be more consistent?

I'm a total noob at any kind of tuning and slowly learning.

[S2H]

I don't mean to jack this thread or anything and I'm usually one to keep my mouth shut and ears open.

All I do is bracket race my car period. Now that Fall is getting near and temperatures will vary from 90-100 in the day and low 60s at night what can I do to keep my car more consistent?

I've built a SUX2BU style ram air and I located my IAT in the tube. It doesn't heat soak or anything, but the temperatures change here drastically going from day to night.

Will changing the bias to 1.00 meaning it's 50/50 IAT and ECT be more consistent?

I'm a total noob at any kind of tuning and slowly learning.

it varies depending on dynamic cylinder airflow...
you cant just put a flat value...
its gonna be a curve...higher at lower airflows and lower at higher airflows

[printmanjackson]

if it goes lean as your IAT's go up, then you need to add to the bias temp table.. if it gets richer.. then you need to decrease the values in the bias temp table.

I have set up the Histogram like you describe and mine is very stable everywhere until a very cool night when the IAT dropes below 50* and just my idle will go real lean. Does this mean I need to move the number up in just the 79 Dyn Air column?

I have my IAT sensor reading at the air filter inside the housing.

I wanted to add that I have noticed that there seems to be a pretty big span between numbers that make a column go either rich or lean at idle.