TTS - table(s) / Which cells to change timing at startup

[pauly]

Hi all,
It's been a few years since I've hooked up my tts and made changes to my tune. Theres only one area I'd like to tweak, and that is when I strat the bike when it's warm.
When the bike is cold, the start up is perfect, but when warm (like restarting at a petrol station), sometimes it'll Kick back or backfire when I turn it over.
I'd like to retard the timing a little in the correct areas but, as I said, it's been a while so I thought I'd ask your advice;
Should I change the main two timing tables, and if so, in what cells?
Or
Is there a table that controls the timing based on temp that may be more appropriate?

[EDIT]
Here's some data from recordings

TEMP    RPM   TPS   MAP   SPARKF   SPARKR
18   1279   0   40.6   26.5   26.5
22   1206   0   36.2   25.75   25.75
25   1136   0   36.9   24.75   24.75
66   1005   0   36.9   21.25   21.25
68   1018   0   36.5   21.5   21.5
96   1012   0   35.1   21.5   21.5
97   973   0   35.4   21.25   21.25
100   944   0   36.2   21.25   21.25
104   1007   0   36.5   21.5   21.5
105   956   0   38   21.25   21.25

113   965   0   36.2   21.25   21.25      
116   984   0   34.7   21.5   21.5
118   1007   0   34.7   21.5   21.5

120   1000   0   35.4   21.5   21.5

So... as the bike starts beautifully when cold, I'd think I'd like to only take a couple of degrees off the timing when the temp is above 100C, the MAP is between 34 & 40, the rPM is below 1000, and the TPS is 0.

What tables?... Hmm... I dee the following with potential, but I don't know thw inner workings enough to be confident I'm right;

Spark advance - Yes this would do it, but across all temperatures... I only want to do it when the engine is warm
Head temp spark correction - Well... maybe but only adjusts using MAP and Temp.
Spark temperature correction - Maybe as well... Adjusts timing looking at Temperature and MAP
Closed throttle spark - Maybe... adjusts based on RPM and temp
(Cylinder) Spark throttle correction -  I don't think so as it's RPM and TPS value... too broad?

So.... I think I could achieve the result I want (IE, less backfiring when starting while the engine is hot) by adjusting the values in one or more of the tables above, but what is the correct one?

Thanks!
Pauly

[98fxstc]

easy fix if you have adjustable push rods is set lifters of the bottom
makes a huge difference for hard starts
then start playing with your tables

[pauly]

 Hi @98fxstc
Thanks for the reply however I'm satisfied the pushrods are set perfectly. I'd rather modify the correct cells in the timing (or other) tables to resolve this issue.
Thanks
Pauly

[kd]

Pauly, I think what 98 is saying is lifters set not perfect (.100) but deeper (like at least .140 deep) often cures or betters the symptom you are describing.  Hot oil bleeding out of the lifters changes the valve timing and increases the cranking compression.

You don't indicate the year / model, mileage but if it's 07 up Twin Cam there is a real likelihood the compensating sprocket is getting bagged.  Again, the main symptom (before it starts knocking) is the hot start issue identified to yours. Both issues often occur together. 

I guess you have to ask yourself what would cause the tune to change?  Maybe it did.    There's also a real good possibility the lifters are leaking down and / or the compensating drive is getting weak. Something to consider.

[pauly]

Hi Kd,
Yes I do think the compensator occasionally gets crunched in these circumstances. It is an 07 softail. Nothing has changed though (in regard to trhis happening), it's been doing this for as long as I remember, including through a cam change, and 3 sets of lifters amongst other things. I do appreciate your replies but I want to at least start trying to solve this via the tune. I may have to eat humble pie and go the pushrod adjustment route if that fails though! 
Thanks
Pauly

[pauly]

I have a related question!...
What would the map be at startup?

Thanks
Pauly

Hi all,
It's been a few years since I've hooked up my tts and made changes to my tune. Theres only one area I'd like to tweak, and that is when I strat the bike when it's warm.
When the bike is cold, the start up is perfect, but when warm (like restarting at a petrol station), sometimes it'll Kick back or backfire when I turn it over.
I'd like to retard the timing a little in the correct areas but, as I said, it's been a while so I thought I'd ask your advice;
Should I change the main two timing tables, and if so, in what cells?
Or
Is there a table that controls the timing based on temp that may be more appropriate?

[EDIT]
Here's some data from recordings

TEMP    RPM   TPS   MAP   SPARKF   SPARKR
18   1279   0   40.6   26.5   26.5
22   1206   0   36.2   25.75   25.75
25   1136   0   36.9   24.75   24.75
66   1005   0   36.9   21.25   21.25
68   1018   0   36.5   21.5   21.5
96   1012   0   35.1   21.5   21.5
97   973   0   35.4   21.25   21.25
100   944   0   36.2   21.25   21.25
104   1007   0   36.5   21.5   21.5
105   956   0   38   21.25   21.25

113   965   0   36.2   21.25   21.25      
116   984   0   34.7   21.5   21.5
118   1007   0   34.7   21.5   21.5

120   1000   0   35.4   21.5   21.5

So... as the bike starts beautifully when cold, I'd think I'd like to only take a couple of degrees off the timing when the temp is above 100C, the MAP is between 34 & 40, the rPM is below 1000, and the TPS is 0.

What tables?... Hmm... I dee the following with potential, but I don't know thw inner workings enough to be confident I'm right;

Spark advance - Yes this would do it, but across all temperatures... I only want to do it when the engine is warm
Head temp spark correction - Well... maybe but only adjusts using MAP and Temp.
Spark temperature correction - Maybe as well... Adjusts timing looking at Temperature and MAP
Closed throttle spark - Maybe... adjusts based on RPM and temp
(Cylinder) Spark throttle correction -  I don't think so as it's RPM and TPS value... too broad?

So.... I think I could achieve the result I want (IE, less backfiring when starting while the engine is hot) by adjusting the values in one or more of the tables above, but what is the correct one?

Thanks!
Pauly

[pauly]

For anyone looking at this, I think I might understand now, but am happy to be corrected.

I've been looking at the TTS manual which describes a table called 'Closed throttle spark' it is based on RPM and Temperature (temperature of what I dont know - I assume it's the engine?). It's described in the manual as follows;

"3.1.22 Closed Throttle Spark, Front and Rear
The Closed Throttle Spark Tables control timing during closed throttle conditions. This table is used if the TPS is less than approximately 1 percent."

So - With the following assumptions (based on the data)

-When I start the bike, the TPS is at 0%
-When it backfires, the bike is warm to hot (up to 120 degrees C, and above)

So -
I will adjust the timing down a couple of degrees in that table when the temperature is hot, and see what happens!

I have a concern that the table (for my calibration) only goes up to 64 degrees C, and my data goes to 120.
Don't forget, - If I'm being a gimp by thinking this may be the answer - please correct me!

Thanks for the replies thus far.
Pauly

[rigidthumper]

The other thing that sometimes helps is setting the upper right timing to just after TDC (-3°) - when you hit the starter button, RPM goes from 0 towards 4-500, Map sensor goes from 100 towards 40ish KPA.

[pauly]

Thanks rigidthumper ,
I'll add that to the 'todo' list if the results aren't 100% from modding the other table.
Pauly

The other thing that sometimes helps is setting the upper right timing to just after TDC (-3°) - when you hit the starter button, RPM goes from 0 towards 4-500, Map sensor goes from 100 towards 40ish KPA.

[pauly]

Hi again,

Well the problem wasn't solved 100% so I've followed your suggestion - Just about to write it to the bike. Wish me luck!

[EDIT] - It seems much better, however It's cooled down a little from when we just stopped so maybe it needs to get really hot - Ill know on the next ride. I'm hopeful your tip helped a lot Rigidthumper. Good stuff

Thanks
Pauly

The other thing that sometimes helps is setting the upper right timing to just after TDC (-3°) - when you hit the starter button, RPM goes from 0 towards 4-500, Map sensor goes from 100 towards 40ish KPA.

[Ohio HD]

You might want to put the closed throttle spark back where it was. You may encounter decel popping with the timing retarded there.

[pauly]

Hi Ohio HD,

Funny that did happen this morning (approx 3 hour ride in temps around 15C) but only once - I haven't heard that for years! Any idea why that happens?
Thanks for the tip.

Pauly

[Ohio HD]

Unburnt fuel igniting with the throttle closed creates a backfire. Advancing the timing at closed throttle inhibits the fuel from igniting.

[pauly]

Hi RigidThumper,

Well... thanks buddy!
That little tip seems to have solved the issue.
I guess the manual (that said the other table set timing when throttle was zero percent) didn't include when starting the bike.
It's much better now - no hesitation when hot, it just starts.
Thansk
Pauly

The other thing that sometimes helps is setting the upper right timing to just after TDC (-3°) - when you hit the starter button, RPM goes from 0 towards 4-500, Map sensor goes from 100 towards 40ish KPA.

[rigidthumper]