Mbt table

[03cobra_keek]

I'm wondering if during low load will it always command the mbt table. I was datalogging and noticed under low load its consistently commanding high timing between 45 and 50 degs for a long period of time and while free revving and hold it at a lower rpm it will do the same. Anything else I've logged it'll spike timing in that range then go down almost right away or fluctuate.

Any input would help thanks

 

[01yellercobra]

I snagged these from an old thread:

Fuel Source:

0 - Closed Loop
1 - Startup Open Loop
2 - Base Fuel Open Loop

Spark Source:
0 - Cranking
1 - Max Allowed/MBT
2 - Borderline Knock
3 - Torque Control
6 - Low Load
7 - Cold/Low Load
8 - Idle Control Sitting on Min
9 - Idle Control in Control

The timing is going to constantly change depending on a few variables. High timing at low load is a good thing. It gives a crisper throttle response and better mpg. Obviously within reason. But if you're not detonating I wouldn't worry about it too much.

 

[03cobra_keek]

Thanks for the info I suppose my question is, will it always command mbt and borderline with nothing to subtract timing? From what I've noticed is ect and iat2 are the only ones that will pull timing. Or traction control obviously. It just doesnt seem healthy to hold it there. We dont have knock sensors to pull back when its commanding 50 degs for 40 seconds or 2 mins.

 

[03cobra#2]

Great questions. When I get back to finishing my tune I'll be diving into spark tables. From my understanding the ecu will pull from the lower of the 2 tables (mbt & borderline knock). So as of right in my tune thoes 2 tables are exactly the same.

Sent from my Pixel 2 XL using Tapatalk

 

[03cobra_keek]

And on a stock tune borderline and mbt is 1 deg off from each other. The only reason I brought this is up is because the stock spark tables is 20-21 at wot so I dont get how there was any improvement in the spark table other then maybe in the midrange. And I've logged actual spark and it shows that 21 degs at wot so I dont get it. My car was tuned before I bought it and I dont have the info on it so I dont know if it was done with sct or something else. I'm currently using hpt and wanted to make sure there wasnt something disabled. I suppose the only real way to know is to get the dealer to toss in 100 percent stock strategy but i could save that step if someone had the answer for me. Which brings me back to my original post

 

[03cobra#2]

Looking back at your original post I believe the ecu will command the lower of the 2 tables. (borderline knock & mbt). If the final spark you are seeing in your log is different from what is in those tables then you'll need to look at the various spark modifiers in your software to figure out why it is changing.

Edit: just to add. If you think you have a previous tune on your car who knows how the previous tuner did things.

 

[03cobra_keek]

I did compare to a stock file and the only changes were on the boarder line and mbt. Which I put back to stock and then removed 5 degs in the .2 load cells for now. The actual spark is what its command in those tables. My op was about the period in which its commanding. It just doesnt seem right to be cruising and it staying between 45 and 50 deg for as long as I'm at that cruising speed. After I pulled out 5 degs it stays between 43 and 47

 

[01yellercobra]

It sounds high but it really isn't. It's a low load situation. That's how you get the good mpg and throttle response. Is your EGR still active?

 

[03cobra_keek]

I've just never logged another vehicle that holds 47 degs at 2k rpm for as long as I hold it at 2k rpm. All the emissions stuff is on there and my ltft sits around -7 and around -3 mid range

Edit: -7 ltft at idle and around 16-18 deg which is nornal