I'm tuning a 2008 Twincam with a 107 kit, Big Sucker, ported 50mm TB, R&R heads, Cycle Rama CR575s, Fullsac DX pipe, Fullsac 1-3/4 baffles - Using TTS Mastertune.

There are three tables that supplement the Main Spark tables via temperature, and some of them don't make a lot of sense to me. They are:

Head Temperature Spark Correction

Spark Temperature Correction

IAT Spark Correction

Here's the questions:

Head Temp Spark Correction: This table allows you to subtract spark based on head temp vs MAP, and seems useable, with a temperature range from -40*C to 300*C. However, I've never seen a head temperature reading in DataMaster, and in studying the User Guide, I find "Head temperature is not directly measured, and is a complex modeled value based on Time, Load, and Engine Teperature values". So I'm wondering what TTS considers the head temp to be when I'm just cruising down the road - I don't want to subtract spark unless neccesary. I've looked at this table on half a dozen tunes, and all cells are set at zero. Does anyone use this table? If so, what settings have you found to have value?

Spark Temp Correction: Okay, this is where it starts to get crazy. We now have a table of ENGINE temperature (not head temperature) vs MAP, and the tuning comments are: "The value from this table is added or subtracted from the Main Spark Tables. This is best used to add spark when engine temperatures are cold and to remove spark at higher engine temperatures and loads."
Now, I'm assuming that the engine temperatures are what TTS is reading in DataMaster, which I've logged between 105* and 130*C at operating temps on a cool day. The crazy thing here is that this table starts subtracting timing at 96*C (!) and subtracting as much as 4* of timing at 128*C - so if I collect data at operating temp and use V-Tune to correct my timing tables, is this already built in, or does this table then subtract the additional timing after I create the base timing table? And did I just add 4* - 6* of retard to the previous tables? If not, which table takes priority?

IAT Spark Correction: On a cool day, my Intake air seems to run between 30* - 50*C. This table starts subtracting timing at 48*C and takes as much as 5* of timing at 80*C, even more at higher temps. Do I want this?

Some of these tables seem completely irrelevant, and others seem to be taking a lot of performance out of the tune. What have you guys been doing with these tables, and/or what have you found to be the best data to fill them with.

A big Thanks to all who take time to contribute.

 

I use spark temp correction (engine) and IAC temp correction. If you are getting spark activity above 112. Take away from STC table. Practical application is running hard through turns in lower gears and speed. Bike heats up due to ripping through gears with less airflow compared to 90mph down the highway tank to tank. IAC temp correction is usually a transition from just off a period of idle. Pulling away from a stop sign. IAC temp change rate is much higher. This table adjustment is rare.


Vtune3 does address Spark Temp Correction along with the main spark table. I look at it as tuning the engine for best performance available for the condition over taking performance away. Before we tuned for worse case scenario, and it was good enough for all.

 

Thanks for the response. So you're saying just leave the Head Temp Spark Correction at all zeros.
With Spark Temp Correction, you start by leaving the numbers that are in there already, then when you say "Spark Activity" do you mean audible knock, or knock retard in DataMaster at 112* C or above?

Leave IAC table as is, unless I'm getting knock when taking off after idling for a while.

Correct?

 

Remember and engine runs best at the proper spark advance. That doesn't mean the proper Spark advance is the same in all conditions. So the RPM and MAP are the same but the cylinder head is hotter or colder where would you correct it? Same goes for Air Temperature.........

 

Spark activity is what datamaster shows me. The ECM's reaction to what it sees with ION sensing. I call it spark activity because it can have timing pulled even though there isn't active knock.


I usually leave the values in the Spark temp correction table, and heat up the bike and collect data. If I am not getting any activity. I might remove some retard from this table and test again. This way I also checking that this table isn't to far retarded to begin with.


Yes, get all this straighten out the best you can. Then if you are still getting activity coming off a long idle with IAT high. Then start to address it here.


I'm sure this is understood, but worth a mention. I don't usually do anything with timing until I am happy with my VE mapping and target choice.

 

Sure Steve, I get that - and thanks for chiming in.

What didn't make sense to me was that spark is being subtracted at and below normal operating temps, and I am collecting data at normal operating temps. It would seem that "normal" would be zero, and as the motor got hotter from there, we would start to subtract spark. It didn't make sense to me that I would gather data, adjust a table, and then 4-5* degrees of spark would be deducted from the setting I just created.

Am I correct in thinking that, or still confused? Thanks for your input.

 

What calibration are you looking at?

 

stock 617 and 358 softail seem to use Head temp, with Engine temp all zeros.

Even then, there is no retard until the Head temp gets up to 179/185ºC

 

Ah, okay maybe we're getting somewhere. I am looking at four different tunes in the starting tunes in TTS for air-cooled touring 2008-2009, and this table is exactly the same in all of them, so I thought that was just the norm passed down from a stock tune. Maybe it DOESN'T need to be set up like this. I will check some other tunes outside of this category.

Here's what the table looks like in my tune now.

 

HrdTail, the calibrations are DAC205, DAD205, and DAG205.