91-94 240sx ecu self diagnostic capabilities?????

[ShouldaHadaV8]

I have read in the FSM about the ecu's abillity to self diagnose problems with a little red light. i haven't heard much about this i wanted to hear some input on how it works before i try anything

[ShouldaHadaV8]

Bump

[ShouldaHadaV8]

i think its turn engine ON, let it run. shut it OFF , turn the ecu screw clockwise and then counter-clockwise to access mode II. ( this should be when the red light flashes for the code reading correct?) and turn it clockwise then counter clockwise to go back to normal.

[poshatch]

you got the fsm right? it the procedure for self diagnostic

turn the key to the on possition...turn the screw clockwise wait 2 seconds then counterclockwise and the red led as well as your check engine light will flash the code your throwing once your done...just turn the key to the off possition...i think turning it back and forth again resets the ecu

[ShouldaHadaV8]

thanks im gonna see what it says

[poshatch]

good luck. hopefully it reads 55!

[vancouverbc]

get a consult cable so you dont have to take the computer out to retrieve codes and reset codes.

1991-1993-240sx-obd-1-consult-t400851.html

[ShouldaHadaV8]

Sounds like a good investment to me.

im trying to get to to the bottom of all these electrical problems. my relays dont work and my battery keeps draining, and it just doesn't idle right. i bought the replacement oem lower harness hoping it will fix the problems. but i would love to be able to datalog, it would save alot of guesswork.

[ShouldaHadaV8]

It reads 55. It doesn't make sense.
My car idles fine but when I give it gas it boggs bad, unless i ease on it then i can slowly give it more and more throttle but it still chokes a little.
I replaced ALOT of parts, fixed the grounds, im not really sure what the problem is.

[poshatch]

55 from the ecu if you did it right means everything is ok at the ecu's end, so everything the ecu is sensing is ok, so i guess you could say you could rule that out but that dosnt seem likely that your car would bog if everything in the running of the ecu is fine ya know...spark issues at all?

[ShouldaHadaV8]

I Think I figured it out. I let it idle for about two minutes it got to rev up pretty high but it was still bogging. I tested the ECU again and that time it came back 34 and the kncok sensor its one of the only ones i didn't replace. i think thats gonna fix it
I HOPE.

[S14Magician]

any luck with the knock sensor fixing it? if not try your maf sensor it sounds a lot like what my s14 was doing when i bought it a few years back and it was the maf

[poshatch]

I Think I figured it out. I let it idle for about two minutes it got to rev up pretty high but it was still bogging. I tested the ECU again and that time it came back 34 and the kncok sensor its one of the only ones i didn't replace. i think thats gonna fix it
I HOPE.

knock sensor malfunctioning from the ecu would retard your timing by 5* maximum i think is all the control it has

so unless your timing is set really badly retarded and it retarded it an additional 5 * maybe it could be bogging

[ShouldaHadaV8]

i dont have a timing light. http://www.nicoclub.com/articles/images/timing-02.jpg if this IS where the stock ka is supposed to ( 20 from TDC i might need to look at it better i think its just at TDC. hmmmm I will look at it tommorrow

[poshatch]

i dont have a timing light. http://www.nicoclub.com/articles/images/timing-02.jpg if this IS where the stock ka is supposed to ( 20 from TDC i might need to look at it better i think its just at TDC. hmmmm I will look at it tommorrow

give us an update when you can

if your at tdc and your knock sensor is retarding it another 5 degrees your chilling at 25 degrees more retarded than it should be

that means that the piston has already gone up and down a bit before its even firing...usually...it fires before the piston hits the top as in stock timing being 20 degrees below top dead center...

[ShouldaHadaV8]

I put the timing on 20 from TDC and it still idles good but if you give it any gas it wants to bogg , if you give it too much it dies, so nothing changed although the timing WAS crappy.
im sooooooooooooooooooo lost as to where to begin ,I still think it feels like an A/F mix problem but I dont think thats the case. who knows, I will figure it out when I get more money for a consult cable, and a spare laptop.

[ShouldaHadaV8]

I think i need to just start finding a way to figure out A.) Why my relays dont work( AND ) B.) why my battery drains constantly
Maybe some weird little electrical flaw in the sytem is causing the bog ???????? Im almost out of ideas as to what it could be.