Technical Topics specific to the Hatchback body - NOT where you post pics/build specs of your car.
By mmnessari
#90620 Once again another question and i come to you guys.. I have a 92 hatch which i bought with b20/b16head and dont know all the mods other then what i can see. 2 days ago i replaced my old battery with a new one. After dropping new bat car seemed sluggish.. Then i noticed vtec wasnt kicking in until 5500 or close to 6000 but b4 it would kick in at 5000 rpm? and im gettin much much better gas mileage.. did i reset the ecu somehow or messed up the tuning?
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By suspendedHatch
#90792 Replacing the battery resets the ECU.

What ECU is in the car? Is it chipped?

You said you get better mileage but the car feels sluggish?

I don't think the OEM tach is accurate enough that when you're blasting at full throttle to gauge when VTEC activates. Not by 500 RPM. BUT... I'm not there with you so.. I dunno.
By mmnessari
#91046 i figured... i have no clue if it was chipped or not. but i know vtec kicks in much later in the gear before the battery change.. ya i am gettin much better mpg but im hurting in terms of power. it is a p28 ecu no clue if chipepd or anything else done to it.
By mmnessari
#91223 btw. i forgot to mention i do have an autometer tach hooked up
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By boosted94
#93977 Quote:

"Another method of resetting the ECU, which I feel is quicker and easier, is to just pull off the negative terminal on your battery. All that is required is a 10mm box wrench or socket and remove the NEGATIVE terminal post on the battery. There's no waiting time involved, just remove for 1 second and then replace it. Make sure you tighten the terminal down firmly but not too tight. This is my preferred method of resetting the ECU. Both methods will work.

That should clear any CEL or for whatever reason it may be that you needed to reset the ECU. Enjoy!"