Relearning ECU

[spiritfc]

Hi,

I've read a few (old -Year 2000) articles about the ECU on LS1 Holdens. Basically they were saying AFM Gen111's there is no point doing mods because the ECu 'relearns' and brings the improved power from your mods back to stock power.
Is ther any truth to that??

Cheers!!

[Space Pope]

Hi,

I've read a few (old -Year 2000) articles about the ECU on LS1 Holdens. Basically they were saying AFM Gen111's there is no point doing mods because the ECU 'relearns' and brings the improved power from your mods back to stock power.
Is ther any truth to that??

Cheers!!

It was more true before various tuning methods hit the scene. People used to 'bolt on' ported mafs etc in an attempt to 'trick' the ECU in to leaning the air/fuel mixture which in turn produced more power. Often referred to as a 'smoke and mirrors' approach. It was also far from accurate and caused pinging in many cases...Pretty annoying and not that great for your motor.

Now, within a short time, the ECU would sense he variation caused by the modified MAF and correct the A/F and spark to bring it back factory settings.

When products like LS1 Edit arrived, tuners were able to access fuel and spark parameters directly and accurately, making changes to the acceptable ranges. This not only liberated more power across the entire rev range but elminated pinging (because the right mixtures and spark are still safe for a given RPM).


'relearn' is history ...just ensure you get the thing tuned and turn your back on ported / modified MAFs....pretty much junk.

[HSV,_I_GOT_ONE]

What about exhausts? People talk about getting more power through aftermarket exhausts but is there any point in getting one (power wise) if the computer is just gonna put the car back to stock out put if you dont get an edit or MAFless done?

[Space Pope]

Exhausts seem to survive and My VXI 2 x 2.25" gained around 15rwkw (remembering that the OEM exhausts on those cars were nothing short of a strangled disgrace). Plenty of guys did better again. Each car is different.

Not sure what the yield from a headers and exhaust alone is these days , the exhausts on VY onwards are pretty reasonable in comparison to the earlier efforts.

Short answer is , whatever you gain from an exhaust, you keep. It's mod'd MAF that tend to blow the ECU's mind big time.

When you can get an edit done, you will see how important that exhaust becomes. Some nice gains to be had.

[Beej]

The way it works (roughly) is this - the LS1 ECM has (in adition to a whole bunch of other fuel/spark maps of course) a target AFR for various modes of operation (part throttle, low speed, WOT vs RPM etc etc etc). So if you use something like a "smoke and mirrors" MAF to try and fool the computer into thinking there is less or more airflow than there really is and thus have it lean the mixture a bit or whatever, the ECM soon learns via the O2 sensor feedback etc that the car is really running too lean, this causes it to build up long term fuel trims to richen things back up again in an attempt to run at the programmed AFR settings - thus taking away any power gains you might have soon on the first day on the dyno.

Now - if you add an better flowing exhaust system, or improve the CAI etc etc such that the engine actually DOES get more air into it and through it at WOT, then the computer via the normal maps will add the corresponding extra fuel, thus producing more power due to higher volumetric efficiency of the engine (ie, better flow), even while maintaining happily the factory set de-tuned AFRs. The ECM knows there is more air because the MAF (correctly) will tell it.

So yes an exhaust system and intake mods can and do make more power out the engine that will last over time. Of course an edit/tune will find more power again, as then you get to update the target AFRs, fuel trims, spark maps etc (and in the case of MAFless tunes VE tables etc) to ensure that the engine is running leaner mixtures and more spark advance than the de-tuned factory settings at all times for more power.

Cheers,

Beej