sbcgenII

iTrader: (1)

ECT will have better control over fueling for idling and normal driving. ECT sensor will respond to slowly for anytype of PE driving though.

denmah

iTrader: (2)

i dont have a log saved, but if i would cold fire the car, and it would idle with 50f inlet temps, if i sit, and it gets to 90f inlet temps it has gone from

13.0 AFR idle to nearly off the wideband 16.50 or more and undrivable.

if its 17.0 idling at that point, then i unplug the IAT, it goes 10.0 afr...

denmah

iTrader: (2)

look how nice and smooth that fueling is!

soundengineer

iTrader: (16)

as it should....
the way a VE table works is a calculation based on the Ideal gas law (PV=nRT).... temperature is part of the equation.


the point is... that you need to tune your bias table to find a value that works as it doesnt work with 100% IAT control as your fuel heat is part of the factor involved...

again.. its why the bias table needs more bias towards ECT at idle and more bias towards IAT at WOT..

every car is different, because every car has physically different properties of
how much heat gets into the fuel and the air based on mods.
somebody with a cold air intake that truly pulls from a cold air spot, will have a table biased more towards IAT...
while somebody completely stock will bias more towards ECT
somebody with an aftermarket fuel system and a return style regulator will have less heat in the fuel than somebody with a stock deadhead style fuel system... the stock deadhead system will be biased more towards ECT because it picks up more heat than a return style system.

danieloneil01

So where exactly is this bias table at in hptuners? Better to install the IAT sensor in the front or rear of the IM?

soundengineer

iTrader: (16)

Engine - Airflow - General


make sure you are viewing things in "Standard" or "advanced" viewing mode, as it is not visible in "Basic" mode(in the top menu--- Edit - View - Basic/Standard/Advanced)



as far as IAT position...
I like it just behind the throttle body at the front of the manifold

danieloneil01

A file from last year. IAT is around 90* in beginning then IAT is around 75* at the end.

danieloneil01

I went to Advanced view right away.

James@ShorTuning

I am not using a fbody sensor to place in the IM. Look back at some older OBD1 GM apps that had the MAT sensor mounted inside aluminum intakes. Those sensors are shielded much better to the outside elements (engine bay heat). So I use those sensors so that the temp inside the manifold is what temp the reading is reported which will give stable results.

The best method however is still getting the IAT to where it cannot possibly heat soak and then dialing in the bias. EFILive has a MAT PID to log which is the result temp based on the Bias, IAT and ECT. There is no PID for logging actual bias value so this can be back calculated to determine bias and then you could make accurate corrections to properly dial in the Bias table.

danieloneil01

Is the AFR going lean based on the wrong temp calculation due to heat soak of the IAT? If the VE is within +/- 2% during say spring temps should the fueling still be spot on if it's not actually heat soaked and you're really getting 90*+ due to summer months?

James@ShorTuning

That would be correct, if the MAT was actually seeing the 90* temps that are being reported then the air would be less dense which would agree with the less fuel being injected.

As you can see by the description below it is important to not allow the IAT to get false heat soak as it adds another variable to the equation that cannot be adjusted for. IAT is inlet air temp, not inlet air temp with some heat soak. The Bias in itself is setup to account for heat soak of the incoming air. So if you allow the IAT to heat soak you are basically baking in double heat soak into the calculation.

Here is the description on Temp Bias:

danieloneil01

I appreciate you taking the time in helping me understand what's going on. Once my car is back together I hope this will fix my SD woes.

soundengineer

iTrader: (16)

also, the Bias table in some ECU's is 0-1 (meaning 0.5 is the middle)
in other ECU's its 0-2 (meaning 1.0 is the middle)

so be sure to look at your table to see what you have before you pick a starting point....

danieloneil01

Mine is 0-2. I'm assuming the g/sec is the Dynamic Airflow and if that's the case from idle to cruising it's below 100 g/sec but once I go WOT it's way above 150 and maxes out shortly after.

denmah

iTrader: (2)

ok, so if i datalog LBS minute and then refer back to that BIAS table, i can just change the lb minute for slow driving out of boost air flow numbers towards 2.0 for less effect over the air fuel numbers, i didnt get to catch up on everyones posts yet.

soundengineer

iTrader: (16)

bias table airflow is in lbs/hr...
so dont forget to click the PID in the main table and change the units to lb/hr and plot units in a histogram in lb/hr as well...

the way I do it is to plot a table that has Bias lb/hr across...and then plot by IAT downwards...
then use AFR error and you can see the averages spread across multiple IAT's


then you can make adjustments by eye...small amounts at a time.


also, you need LONG LONG logs with lots of data....and dont start logging until you are up to full operating temperature for atleast 15 minutes(guarantees all fluids are up to temp and the engine and fuel lines are evenly heated)
and you need 30-45 minute drives...
and of course it will take multiple times of doing this as you slowly adjust.


its not a simple one data log and done pass to get it correct.

denmah

iTrader: (2)

thanks for the help, i would love to learn and get it perfect but for now the resistor is a beast haha

ill go over everything then, this has been a learning experience thanks for all the reply's dudes

danieloneil01

Make it easier and use metric for everything. I plan on just messing with everything below 100 g/sec. This should cover idle and cruising.

soundengineer

iTrader: (16)

Just be sure to look at the entire tune in metric if you choose to use g/sec for values...other wise..if you look at the tune in Imperial..the table will be in Lb/hr

danieloneil01

The only I hate is C*