Hey all, I'm new to the board and I have an irritating problem maybe someone could shed some light on. All suggestions/diagnosis appreciated....

I have a 95 240sx/5 speed, i recently got hold of a 96 engine (42K miles/$425.00)from a 96 SE /AUTOMATIC. Engines in , runs fine (99% of the time) however the check engine light refuses to go off. I get differing info from all my "mechanic friends" relating to the ECU being the cause because the ECU from the 95/5 speed is still being used on the 96/automatic engine replacement. Would this cause a problem and does the ecu need to be reprogrammed or replaced or by being reset can it "learn" that the auto tranny is no longer in the vehicle and it's now a 5 speed? For that matter can the ECU even BE causing the problem? it's all greek to me, but maybe someone knows the answer or has a suggestion for a fix. And, yes the O2 sensors are all new and working.

Kevin

 

Have you tried scanning the ECU to see what code it throws out? Also after 95 didnt 240s run OBDII, so that might have something to do with this. Im not sure if you run a auto ECU on a manual car that the check engine light will be on, could be a possibility.

 

Correct me if I'm wrong, but don't auto and manual ECUs have differences, like different sensors, etc.?

 

i was wondering that as well...

you ARE using the 5spd tranny from the 95 KA right?

 

"you ARE using the 5spd tranny from the 95 KA right?"

That's correct. and to update a little i was "told" earlier today by a "supposed" mechanic ( who moonlites @ advance auto parts...for what it's worth) that the light will NEVER go out until i get the ECU that went with the 96 engine ( w/auto tranny) that i bought and install it back with that engine.

Truth or BS ?

 

That sounds like bs to me, you should be able to just "rework" the ECU with out having to get the one from the other car

 

how does one "rework" the ECU ?

When it comes to fixin this car, except fo basics, i know nothing. I have to depend on my mechanic's judgement. I've owned this car THREE TIMES ( i'm sentimental and keep buying it back). The last guy who had it before i got it back again was in a wild three parish (county) Police chase that ended with his attempt to take it swimming in the Red River ( fortunately for the car, he got stuck on a sand bar and didnt do much damage or submerge the car. I managed to get it back @ the city marshal's auction for $166.50 this time and had the new engine installed in it. It's taking a bit to get it back to the way it "was" last time i sold it (excellent shape) but it's progressing, and this ECU/CHK ENG LITE is just one of the hurdles to be overcome.

 

you could get an ecu from the 96w/manual that sounds like it should do the job, it makes the most sence too... or just get a fuel manegement system and ignore the check engine light...

 

I know there was something about how the 95 was different from the rest of the S14s... something about OBD or what not. I can't exactly remember what it was, but Im sure someone here will read this and remember for me

 

yeah, they are the sucks, 91 ka all the way... lol 95+ is when OBDII was implimented so that shouldnt be the problem.. like i said a 96 manual ecu should do the trick.... or you could put your ecu into open loop (or was it closed loop that does this) and it will just run the motor with out taking in any sensor info and just go by the baseline of air/fuel for the stock octane... (on a side note, i serously think that the 240 was ment to run off an 89 octane, cuz it runs like KRAP on 87 and stock ignition system isnt strong enough to run 92)