ok so here is the update..
the speedo stopeed working for some reason, took me entire morning to diagnose it, the VSS (vehicle speed sensor) is a two wire one, out if which one needs to be connected to ground, the other goes into the speedo, the signal is a sine wave. than speedo converts it to square wave and sends to the ecu, the ground wire was not connected, after making the connection the speedo worked.
here is the video i made of the VSS when i had diesel engine, same signal in the new setup too.
//youtu.be/http://www.youtube.com/watch?v=fgDFwCp-jnk
than went for a test drive on motorway, the car behaved fine alhamdulillah, the engine is quiet gutsy, there was no vibration or any other odd feeling, but after around 100 or so km's the CEL (check engine light) lighted up, we stopped at chakwal interchange and tried to figure it out, everyhting was fine, tried resetting the ecu by disconnecting the battery but the CEL remained, we came back, there was no loss of power, engine was not in limp mode, thus we came to the conclusion that the fault is not serious, over night i disconnected the battery, but in the morning the light was still there, checked each sensor in detail. the o2 sensor had a wire disconnected from the connector.
now a bit of detail on the o2 sensor.
its fitted in the exhaust and tells you the amount of oxygen in the exhaust gases, thus figuring out the air fuel ratio. now the sensor needs high temperature to operate, and if it is not very close to the head that temperature is not reached. hence now sensors come with an in built heater to heat them up.
-1 wire sensor - no in built heater, just the signal output, ground is taken from sensors body
-2 wire sensor - built in heater, one signal wire, one power wire for heater, ground for both heater and signal is taken from sensors body
-3 wire sensor - built in heater, one signal wire, one heater power wire, one signal ground
-4 wire sensor - built in heater, one signal wire, one power wire, one signal ground, one heater ground.
than there are wide band and narrow band sensors, narrow band(found in cars) only tell if air fuel mixture is rich or lean, wide band usually after market tell exactly by how much the mixture is rich or lean, now wide band sensors have also started coming in cars for better economy and emissions.
ok now coming back, the qg18 that i have has 3 wire o2 sensor, the heater power wire was disconnected, though i don't think that the CEL was due to this as in a long drive the exhaust gasses are hot enough to heat the sensor, hence i think the sensor is failing, as was expected in an old engine, as these sensors have limited life.
i connected the wire, but again the CEL was there. now i needed a scan to find out the problem, though as the engine is a swap and previously the car was not efi hence there is no obd socket present to plug the scanner, so i was stuck.
anyway researched a little and to my surprise nissan is still giving a manual way to diagnose, basically you jump "chk" wire with ignition while the ignition is on, The CEL light blinks and tells you the fault codes.
the procedure is
-turn on ignition
- jump "chk" to ignition
-hold for two seconds and then take out the jumper
the light will turn of than start to blink, number of blinks tells you the digit, with 0 represented by 10 blinks, 4 digit code with small interval between digits and relatively larger interval between codes if there are more than one, the codes repeat unless you turn off ignition.
my fault code came out to be P0130 (02 sensor circuit malfunction).
if you jump the wire again while ignition is on the codes are reset. i did this and the CEL vanished.
previously when i was trying to reset the ecu, the CEL wasnt going because the ecu needs 24 hours of power off to reset itself, i only gave it maximum 12.
so done with this problem, now i need an o2.
secondly i was looking for the refrigerant pressure sensor to get the ac working, no ac shop had any idea about it, and i searched the second hand market, no one knew about it. than today i went to the market and searched for the front cut of any newer model nissan, and voila , found n16 front cuts, asked the guy and took out the sensor, costed me 1500 with grip, quiet high as per local standards but hey, i needed it and getting one from abroad was atleast 50$ without shipping, hence got it.
now inshallah next weekend if everything is ok , will go to the ac guy to get it functional.
