I was told that after a mod, say an Intake manifold that the ECU has to relearn the upgrade. Is there anytruth to this? Im not talking about when running hondata, chrome, neptune, etc. this is just on the factory ecu.

 

I think it is like breaking in a motor. You don't want to be smashing on it right away you need to give it some miles first depending on what you added to the motor before you start smashing on it.

 

OBD2, yes. due to long term fuel trims
OBD1, no.

all though resetting the ECU after messing with the engine is a good idea for any setup. Just in case something you were doing caused some sort of temporary problem.

 

Good to know.

 

Yeah, I always reset the ecu after any mods to clear the long term fuel map. The ECU can then make the tiny tiny changes it does to accommodate it's new "diet." Doesn't do much but I do it cause it makes me fee better, lol.

 

How do you reset the ECU?

Are there possible negative side effects?

I just installed a used one in my Civic to solve an A/C problem and I am hoping this might help solve my drop in gas mileage.

Thanks

 

Disconnect the battery for 1-5 minutes, then hook it back up, turn the car on and let it run for a couple of minutes. That should do it. The ecu track stuff like fuel/air mixture and remembers it so it adjusts to the conditions it's in. You would want to reset it after a change in elevation/location, or if you add something new to the engine, etc.

 

removing the ECU is also a good way to reset it.
anytime it looses power it resets itself.

1-5 minutes is overkill IMO, anything more then 30 seconds is pointless. Provided you don't have stereo or amplifier caps that hold the battery potential for longer. A quick flip of the headlight switch usually is more than enough to kill that.