Using zero pedal torque to correct idle external load table

[Dominatorstang]

I find a common agreeance to set the idle external load table using data gathered from logging zero pedal torque. I set up a table on the scanner to match the idle external load table, but being a truck I have no engine oil temperature sensor. The scanner just shows -40 the entire time. So I figure the ECM is just using that first column being -40, but I see many modified truck tunes that are setup as if the entire table is being used. So this makes me wonder if it is actually using calculated engine oil temp or something other than the -40 reading?

super cold start and drive from work.hpl
idle tweaks two.hpt

[Dominatorstang]

Also, the values of zero pedal torque change when in gear vs neutral for an automatic. So is it best to log both and average between them?

[BDPhoto519]

Interesting concept... I haven't heard of this method before. Care to explain the process a little more?

I setup a table in the scanner to match the idle external load table... The table doesn't mention the units but I am assuming it is in ft/lbs. Are you just directly changing the values in that table directly with what you are getting in your log tables? for example copying the entire log table and "adding" it to the existing tune table so that both the +/- negative values are being changed?

Thanks.

[Dominatorstang]

The way I have read it to be done on a few posts by some trusted folks is to log and copy it over directly as is. And the Idle torque limit offset is used with these values to give a range the ECM can work in.
I know it makes the values look way small, but that is how it is done unless I misread. Below are the places I read it.

https://forum.hptuners.com/showthrea...+external+load
https://forum.hptuners.com/showthrea...+external+load
https://forum.hptuners.com/showthrea...+external+load
https://forum.hptuners.com/showthrea...+external+load
https://forum.hptuners.com/showthrea...+external+load


I am now just trying to understand if the trucks only use the -40 column since they do not have a sensor or if they use a calculated oil temp. I may end up just throwing some odd values in to see if those other columns even effect it.

[07GTS]

there should be a oil temp calculation pid if no actual sensor and that will give u values

[Dominatorstang]

I had seen the calculated engine oil temp too. I just was not sure if the table uses that one for vehicles that do not have the sensor or not. Have you noticed the table referencing the calculated engine oil temp on some?

[07GTS]

my cruze turbo uses the oil temp calc, also many use the IVT temps which is a major fueling calc, MAT, ITT all calcs used, more then just actual sensors are used alot of the time

[pisces_0]

I've used this exact graph to dial in Idle External Load. Works like a charm!

Calculated oil temp on the X-axis.

RPM on the Y-axis.

Plot Zero Pedal Engine Torque average.

Copy over directly into the table.

All caveats regarding correct/accurate VVE, MAF and torque tables apply. Garbage in, garbage out...

[TriPinTaZ]

I've used this exact graph to dial in Idle External Load. Works like a charm!

Calculated oil temp on the X-axis.

RPM on the Y-axis.

Plot Zero Pedal Engine Torque average.

Copy over directly into the table.

All caveats regarding correct/accurate VVE, MAF and torque tables apply. Garbage in, garbage out...

Copy over meaning replace, or did you mean Paste Special > Add ?

[pisces_0]

Copy over meaning replace, or did you mean Paste Special > Add ?

Copy the Zero Pedal Torque values from the histogram and directly replace in the tune. No special paste adders or multipliers needed on this.

Depending on the mods and current tune, the values may change substantially. I used this method when dialing in a larger cam, Whipple SC and 103mm throttle body, and the table decreased quite a bit. Adjusting this table, and polishing the tune elsewhere, produced a rock-steady idle at 720 RPM with 6*-8* of timing.

[jasonz28camaro]

I’ve found areas in my truck OS that uses trans fluid temp as the oil temp reading. Not sure if it’s this same situation for the zero pedal tq though.

[Dominatorstang]

In testing I would have to agree that this table on vehicles without the physical sensor, does end up using engine oil temp calc.

[Haans249]

Copy over meaning replace, or did you mean Paste Special > Add ?

Should be a direct copy and replace, no adding.

[TriPinTaZ]

Interesting. I have not found a direct copy and paste of the average to be the answer for me. I trend the tables in the direction of the zero pedal torque output from the graph and smooth with good results. Not saying I am correct, just commenting that is how I do it.

[BDPhoto519]

Interesting...

I will have to play around with this when I have some time next week. My idle is rock solid as-is, despite adding the 105mm HiRam & Katech 103mm TB so I am a little concerned with messing it up at this point. But I am always looking for ways to better calibrate my tune to match my setup and learn new things even if its just for good house keeping.

[TriPinTaZ]

As I mentioned, it doesn't mean I'm right. If your car doesn't have any issues, maybe don't mess with it.