Ecu ghost

[IBCNYA]

I have a self learning civic...Sounds nutz huh? I swapped my car to mpfi back in september, also dropped a d16y7 into it, with a 91 si tranny and a pm6 ecu. Since then its run good, strong for what it is and banging the gears out till it hits its rev limiter at 7000.....until the other day when it banged 7500 in third on the interstate. I thought well maybe my tach is off so I got in it again, nope my top speed in third had gone up from 90 to 94-95..... Most everyone I know has a honda and we cant figure it out. Ive nor have they ever seen a ecu increase its rev limiter on its own without being chipped. Anyone who finds this a bit interesting, I wanna here what you think it might be. Its a 1991 pm6 ecu. Obd0...

[d112crzy]

When ecu's are in closed loop, they learn

Anyways, did you add any modifications to the engine or change the tire size?

Even a slight wind going with you could have upped your mph.

[IBCNYA]

What does it mean when the ecu's in a closed loop??? No I didnt do any mods before the change. A stock untouched pm6's rev limiter is 7000. Ive never heard of this before.

[IBCNYA]

What does it mean when the ecu's in a closed loop??? No I didnt do any mods before the change. A stock untouched pm6's rev limiter is 7000. Ive never heard of this before.

Closed loop operation occurs when the engine is idling, or running at near-constant throttle position at near-constant engine speed. During idle, the ECU actually has two goals: one, to deliver the correct fuel, and two, to maintain the idle speed at 750 RPM. The fuel is handled by controlling the injectors and using the oxygen sensor for feedback.

[d112crzy]

Good job.

I was going to post, then decided that I would let you search on your own before I posted anything else.

Closed loop is a system the ecu uses. It gets feedback from all of the engines sensors, then decides what to do with the feedback and results in the output. It's storing every change into its memory as well.

Anyways, even a change in temperature could have caused this.

[IBCNYA]

I guess its a good thing though. The civic my engine came out of doesnt hit its rev limiter until 7500...so im not worried about valve float. hell id push it a little more if i could, but i wanna get some better valve springs in there first. Float is bad.

[IBCNYA]

pm6 civic ecus lower the rev limiter when theyre still cold.....i just fix my ect and now its work....with out the ect the ecu held the car in cold mode.....this is why the rev limiter changed....normally when warmed up the car s rev point will be 7500. ok yeah i got it...