How the MS3 ECU Adapts...

[Speedy3]

A Mazdaspeed trainer visiting a local dealer here in WA talked to my friend who was having ECU problems with a FMIC and catless exhaust install. He told him it takes 8-12 engine cycles and at least 5 min of driving each cycle to adjust to system changes (sensor readings). He said that the ECU basically will adjust around 10% each cycle.

Thought this info would be helpful.

 

[jbiird317]

is this in place of disconnecting the battery or in addition to?

 

[shaodome]

is this in place of disconnecting the battery or in addition to?

Probably either or....I don't believe resetting the battery does ALL that much as the ECU is most likely committing its changes to nonvolatile memory anwyays...

When I first installed my intake I was in a hurry and it was starting to rain, thus no battery resetting. By the 2nd day the car was significantly more powerful without a reset.

 

[Speedy3]

is this in place of disconnecting the battery or in addition to?

Anyone out there correct me if I'm wrong, but this is how I understand it.

Disconnecting the battery starts the whole process out from the default map settings which are set to the stock configuration. The ECU adjusts each ignition cycle starting out making large adjustments based on the sensor readings it gets. adjustments get smaller and smaller after each ignition cycle. It will take 8-12 ignition cycles to get to the goal state (AFR?). Changing a part without disconnecting the battery should have the same effect, but since the ECU already has a correction factor applied, it makes smaller adjustments between ignition cycles to get to the goal.

 

[crossbow]

Though it should be mentioned that ANYTIME you're working in the engine bay...you really should be disconnecting the battery. (Safety)

Not to mention if you drop a tool and it falls in the wrong spot, you can short or damage a sensor. This happened to more then one 6 owner installing an alumnium intake. (destroyed/damaged maf sensor from a short)

 

[Speedy3]

Though it should be mentioned that ANYTIME you're working in the engine bay...you really should be disconnecting the battery. (Safety)

Not to mention if you drop a tool and it falls in the wrong spot, you can short or damage a sensor. This happened to more then one 6 owner installing an alumnium intake. (destroyed/damaged maf sensor from a short)

That's good advice.

 

[dparm1984]

Well considering that basically every single install instruction out there says "disconnect positive battery terminal" as step #1, I thought it was glaringly obvious...

 

[Speedy3]

Well considering that basically every single install instruction out there says "disconnect positive battery terminal" as step #1, I thought it was glaringly obvious...

Clearly obvious. Back to point. Taking the car out for a spin after installing an aftermarket part and coming back saying "Wow, this car pulls way harder!" doesn't really tell you anything about what the part will do after the ECU adjusts. You may be running very lean at first until the ECU can compensate. This may be one explaination why some people have gone Zoom, Zoom, Boom right after installing a bunch of mods.

 

[desperado-c]

Well considering that basically every single install instruction out there says "disconnect positive battery terminal" as step #1, I thought it was glaringly obvious...

But still frequently ignored. I even do it myself sometimes.

 

[AutoXRacer]

Clearly obvious. Back to point. Taking the car out for a spin after installing an aftermarket part and coming back saying "Wow, this car pulls way harder!" doesn't really tell you anything about what the part will do after the ECU adjusts. You may be running very lean at first until the ECU can compensate. This may be one explaination why some people have gone Zoom, Zoom, Boom right after installing a bunch of mods.

I did notice when I first installed my DP, that the car was mad powerful...producing full 3rd gear wheel spins...then shortly after a few minutes of driving...it was gone... (sad)

Never thought about it before... I guess the safe thing would be to drive the car conservatively for an extended period of time before going WOT; just to let the ECU adjust...

In addition, when I installed my TMIC, I did not noticed any improvements immediately...I had to drive the car about 30 mins or so to see an improvement. This also happened with my new BPV...

Good info... I will now be gentle after installing a new go-fast part to give the ECU a change to adjust.

Great info!! (2thumbs)