Does anyone know if this applies to ITRs? http://www.ntpog.org/mods/fifth-afc/ecu.shtml

Basically they said that 5th gen preludes ecu will over time adjust itself after you make a mod so that the increase in power isn't there as much.

 

Its called long term fuel trim.

During cruising situations the ecu monitors how much it must richen or lean the
mixture to make it stoich. After a certain period of time, it will store that value
and at WOT it will apply that value. So for example, if the ecu has to lean 5%
during cruise, it will lean 5% at wot as well.
This is an OBD2 function. Last time I checked, ITRs are OBD2.

 

Thats why you can't use Apexi ITC's on preludes!

 

So has anyone noticed that where they may gain 3hp from an intake, 6 months later they're back to the stock hp?





[Modified by jond, 7:55 AM 9/18/2001]

 

couldn't you just reset the ECU again?

 

You can. But from the prelude article, they're talking about reseting it evey day!
That would be a pain in the ***.

Also, would not allowing the ecu to 'learn' harm the engine in the long term?

 

not sure, i'm not qualified to answer that.

but resetting everyday would be a major pain in the ***. ack . . . !

 

Not necessarily. You could just leave your backup fuse out of the car and rewire the clock and radio to a hard line to the battery! When I was younger and stupider my backup fuse was blown for 3 years and I could never figure out why my clock didn't work.

 

I guess the real question is, is this really a problem. Are we throwing our money away when we put on bolt-on performance products, or do most of the gains stay for a year or so.

If it is a problem, then we'll come up with a solution.

 

Does anyone have any dyno charts done months apart with the same mods? That would prove/disprove this theory.