FireDemonSiC

Can someone elaborate more on how the AFR Enrich Over Time parameters work? How does the coefficient value of the decay and attack rates translate into time?

Basically what I want is for the AFR enrichment to only kick in during long runs or spirited driving. I don't want it taking effect during a quick stoplight romp or a 1/4 mile run.

I was also thinking of setting the AFR delta to 0.7. Any thoughts on this? I already have the tune slightly on the rich side (12.5:1) to help with detonation and to take E10 into account.

RBob

iTrader: (1)

Not sure how technical you want to get, but it is easy to look at a log file and follow the enrichment taking place. Whenever the ECM is in PE mode the enrichment takes place. When not in PE mode it is decayed out.

Setting the max enrichment to .7 is OK, it is whatever works for that particular engine. The purpose is to help cool the engine when in PE mode.

RBob.

FireDemonSiC

That's slightly disappointing. I was thinking it was time based sort of like with an LS tune and HP Tuners. Doesn't start kicking in until the engine has spent a certain amount of time in PE.

Guess I'll be leaving the AFR enrichment disabled then.

RBob

iTrader: (1)

Wow, so you would rather have the enrichment kick-in all of the sudden? Rather then smoothly enhance over time? Have you tried both and come up with a resolution as to why?

RBob.

FireDemonSiC

I would rather the AFR not be molested when it doesn't need to be. I also think some sort of blend filter that control how quickly the enrichment comes in once activated is certainly possible.

Not a big deal. I just don't understand the point behind a logic that alters the AFR from the very moment you step on it if the goal is to tune for max power and your cooling system doesn't have any problems with keeping the heat off.

RBob

iTrader: (1)

Max power is typically obtained at an AFR of 13.1 - 13.2, but that isn't a good idea unless it is a max effort run (such as a big money grudge match).

A change in AFR from 12.8 to 11.8 will lose very little if any power. But it can save the engine from a meltdown. At sustained WOT the cooling system is not going to remove heat fast enough from the piston crowns and spark plugs.

This is where the extra fuel comes in, to directly cool the chamber. And it is a common thing to do. I was going to quote from this article, but it is better to read the whole thing:

http://www.contactmagazine.com/Issue...ineBasics.html

As for your engine and tuning, if you don't like how the enrichment over time mangles the commanded AFR, set the delta AFR maximum to zero. This is why we give the tuner the many calibration parameters to work with.

RBob.

FireDemonSiC

Good to know. I purposely have the tune richer around 12:1 in the mid rpm ranges for detonation control. This thing would not agree with a long term sustained AFR in the low 13s.

I may enable the enrich over the time and program it with a small value, such as .5 and adjust the coefficient settings, just for added insurance.

The delta setting has been at 0 this whole time I've been tuning. Enrich over time has never been enabled.

Gojira94

I'm making use of this in my tune. RBob sent me further information on this if anyone else finds themselves here from a search:

For attack and decay a smaller value is 'slower' and a larger value is 'faster.' The "time" that takes on either end will vary due to how long it takes your fuel setup to deliver enough fuel to meet the commanded Max dAFR (change in AFR) in the PE - AFR Enrich Over Time Parameter. I'd trust the default parameter values for attack and decay to be pretty well suited for most of us as far as how fast to bring in the enrichment and decay it out. I suppose the question is how much does your setup need to meet your desired AFR values from entering to exiting PE mode.