Why the ecu make my tune run richer over time ?
 

I would like to understand why my ecu change my afr ratio over time?

Tony have set my afr to be between 12.5 and 13.5 at wot.

When I reflash with ecutek my afr come back to what it is suppose to.

If I do a log 2 or 3 weeks later I have a flat afr reading of 12.17 all the way until redline.

I do multiples logs and always have the same 12.17 reading.

If I reflash my afr ratio ( graphic ) come back to normal.

Does that means my tune is worth nothing ?

We worked hard to set the car somewhere and it look like the ecu is not keeping the AFR where we would like to.

Sounds like your iam is dropping based on passive driving habits. You're probably somewhere around .5. Those who drive more aggressively have higher iam values weeks down the line. Mine stays around .7-.8. Its normal for NA suby to hover around .5

What does that mean, exactly? If you don't drive hard, you're tune I learns it's way around itself?

well basically in simpliest terms: when you flash the ecu the iam value is reset to its highest point. it will stay there for a bit but drops over time. the iam is total 1:1 ratio of the advance table. so when the iam is 1 you get 100% of ignition adv table. so if it drops to .5 you lost 50%. so if you ign adv was 5 degrees you just dropped to 2.5 degrees. which will see more unburnt fuel leave through the exhaust. so there are two ways to do it. run more timing on the base table which wont allow the ecu to pull as much timing when knock occurs or wait for the iam to drop and adjust the turn accordingly. i prefer the latter. this way you ecu can work as designed when it comes to its original ignition protocol. this is why i review logs over a extended period of time though time consuming creates a better all around tune to each specific vehicle and driver.

Because your stacking up a long term positive fuel trim. More info here

the 370z does the same thing, even with a reflash


the harder you drive the more power it makes..... to a point.

from what ive heard not just form this vehicle but other as well, even when you reflash your ecu and get more power, over a given period of time it will start reverting back to how it used to be with the factory AFR. I could be wrong, its just what ive heard.

Read your writeup on this a while back mad_sb. Muchly appreciated, though a bit over my head. Beyond zeroing this out, is the only solution for those without editing abilities to just continue resetting? I know many people with a jeckyl/hyde complex with this car. Babying it around hyper miling it, and then beating the daylights out of it. Many have talked about how it feels sluggish after a few weeks of playing commuter.

My advance multiplier was playing around .88 and .90 today when i was loging so it was pretty close to 1.

The first picture is the AFR wanted that I got after my last etune reflash on june 26th.

Second and third picture is my afr on july 23th.

I did change the overpipe on july 22th but my afr was already showing 12.17 just before the install. So the overpipe is not the reason why my afr changed that much alone by itself.

If I do a reflash with my last etune I got in june, I bet 100$ my afr will come back to normal where it should be.

why dont you send me the log since you just installed the over pipe and i was expecting your log anyway

So is this issue only on ecutek or does unichip also have this issue?

wouldnt consider it an issue since we have all been able to tune around them thats the difference between ecutek and unichip we have access to hundreds of tables to get everything working cohesively

^This.

This thread you are refering me seem very interesting but too complicated for me especially when English is not your language.

May be somebody could explain here what this thread is all about in a simple short summary...