How does ecu know to add timing

[Beercules]

I'm looking at data logs and know the knock sensors tell the ecu to pull timing... how does it know to add timing when spraying meth?

 

[2011 gtcs]

Your tuner sets up your timing table to add timing as your RPMs climb with a max set timing he allows. Since you're on meth your tuner probably has your max timing set to 19 degrees. The point of the datalog is so he can see how the car is responding to the meth. You need to look at your knock sensors on your datalist. You want to see negative knock. If you're seeing negative knock that means the ECU is adding timing. That's what your tuner is looking at. If you see an positive knock it's pulling timing. You'll usually see up 3 degrees of negative knock on your datalist. If you're seeing that everything is good and he might allow a higher max timing.

 

[Beercules]

So it tries to add 4 with rising rpm (according to tune) but pulls back if it sees knock?

 

[2011 gtcs]

So it tries to add 4 with rising rpm (according to tune) but pulls back if it sees knock?

Basically yes, is Lund racing or BJ McCarty your tuner?
On your datalist you should be seeing something like -1.0 to -4.0 next to knock sensors reading. If you want to see what your max timing is at go to your spark advance on your datalist.

 

[Catmonkey]

It's more of a learning process for the PCM. If it's not detecting knock based on the borderline knock spark tables, it will start to gradually add timing. It's not an instantaneous thing that occurs that adds big timing adjustments. You'd need a tune for methanol and just make damn sure your not out of boost juice. But if you're spraying it north of the rotors, I'm not sure how effect it is anyway. @Willie would be the guy to ask.

 

[VNMOUS1]

I'm looking at data logs and know the knock sensors tell the ecu to pull timing... how does it know to add timing when spraying meth?

There is knock sensor retard and knock sensor adder. Values are assigned by the calibrator. The increments in which it can add/retard as well as the time it takes to perform the task are also assignable.

It has nothing to do with your base borderline knock (spark/timing) table.

Factory cal only retards ONE degree regardless of the amount of knock. There's also Piston Protection which is an additional table to use.

Every car will knock at the hit with a PD blower. Once that initial shock is over, if the base table is somewhat conservative and the adder is on, it will add x amount of timing every x seconds up to the assigned limit.

However, you should set retard to pull more timing and more quickly than the adder can do its thing.

If you are halfway through the pull and the smallest amount of knock (real OR false) occurs, it will pull the assigned amount and won't add again until the time assigned has passed.

If I have a car that isn't knocking in peak Torque, only up high where stuff gets buzzy, and we've physically determined there's no detonation, then I'll put that timing in the base table and not use the adder at all since it wasn't able to do its job when a dipstick tube rattled on a header primary (or some other obnoxious issue)

Hope this helps clarify

Sent from my SM-N975U using Tapatalk

 

[Willie]

BJ,
In your opinion, how "good" is the stock knock retard system? I'm under the impression that it does not compare to some aftermarket systems, some which allow individual cylinder retard.

.... how does it know to add timing when spraying meth?

Message me. I need to ask you a few questions about your setup. Then I'll give you specifics I came up with.

 

[Beercules]

Thanks BJ.

Wish there were free online courses for what the ECU is doing. Not so I can tune it myself, but so I can troubleshoot without having to disturb the tuner until I know it's the tune's problem.

 

[Beercules]

So that's why they say you can have the tuner add a little timing at higher altitude before the cam really kicks in to get rid of the turbo lag feel...It pulls a bunch of timing at the hit. It still spins tires too easily so it's not that bothersome.

BJ, What do you think about throttle touchiness idling through parking lots? Simple tweak or live with it?

Every car will knock at the hit with a PD blower. Once that initial shock is over, if the base table is somewhat conservative and the adder is on, it will add x amount of timing every x seconds up to the assigned limit.

However, you should set retard to pull more timing and more quickly than the adder can do its thing.

 

[Beercules]

Quick question, BJ, if you don't mind. Does the ECU see the added meth (via o2 sensors) and pull fuel to keep the tuner dictated A/F ratio? If so, I should be able to use STFTs to dial in the right size of nozzle (after I get a handle on meth pressure).

Am I thinking correctly here?

Thanks

There is knock sensor retard and knock sensor adder. Values are assigned by the calibrator. The

Sent from my SM-N975U using Tapatalk

 

[VNMOUS1]

Guys, hit me up on email or tag me so I am notified. I am only on here once a week at most.

Throttle question.... It can be backed off.

Timing..... It's the knock sensor system. Retards and adds if commanded to and Conditions are perfect

Sent from my SM-N975U using Tapatalk