Hondata

Alright, had an issue where my lights would dim and brighten while cruising (noticed it at night)

Traced it to my spal fan, drawing power turning altc off.. datalogged and confirmed. now, what is unusual is that FANC will turn on under deceleration only regardless of engine temperature. (which is why i thought it was weird my lights were dimming based on the difference between 0 and 1% TPS... I then tried to use the fanc override option, and now it will NOT turn on under deceleration under 30mph (unless temp is reached, different datalog shows that), but still will above said MPH. It SEEMS it is directly tied to tps... halfway through datalog i disabled ALTC to see if it had anything to do with it.. It would maintain 14.3v unless the fan had just kicked on (due to large power draw.) i'm ASSUMING that if i increase my mph maximum for fanc override, that it will then turn off under deceleration up to my set mph, but will still happen.. say.. at 100mph (over my override mph maximum).

basically... is this the normal function of that output?

BTW this is a 99 crv w/manual trans (stock internals) 630cc ev14 bosch, walbro 255, hy35 turbo at 5500 elev...

You should lower the MPH for the fan override. This will turn off fan control above the set MPH.

if i lower it it works as i'd like UNDER the mph setting, however still turns on under deceleration ABOVE the set mph... if you watch the datalog graphing tps, ect, vss, and fanc you can see. the way i have it it turns off as i decelerate once i get below 30mph, however if i'm decelerating, say from 40mph all the way down it turns off right at 30mph and under...... very easy to see in datalog.

and if you'd like i'll set it at 1mph maximum and datalog once more to show you it will turn on decelerating the whole time from 40 or whatever until i hit 1mph...

I did as recommended and lowered the FANC maximum speed. lowered it to 1mph, and it still turns on under deceleration well above the maximum i set.... is this considered normal FANC operating behavior for a p28 is all i want to know... attached is yet another datalog showing problem

I will have to test this on my own car later this week or early next week as I am currently driving the RSX for test purposes.

well as i've driven more it seems it's not tied to tps, but to the fuel injector overrun cutoff if that helps... as it seems to take a moment after reaching 0%tps position to turn fan on...

So far I have tested 2 vehicles of mine and found no problem like what you have shown. Have you tried a different ECU as you may just have a faulty ECU.

i will try that. a buddy of mine has a p28 with hondata as well.. his is version 2 and mine is version 1..

i will swap his ecu and module into mine and test, then swap my module into his ecu and retest to verify as well. i will post results.. although i am confused as to the ecu would fault in this particular way... very unusual.