just an update.. I been doing my research and found that almost al japanese cars after 1998 have a central computer called ECU,and there is a way to read data from it and even mod it..My car is a Nissan primera which has OBDII interface under the steering column..Your Toyota and Honda must have a white or black plastic socket with 16 pins hidden underneath the steering column.
.Thats the car's ECU port through which you can talk to the car's central processing unit..
You will need a special cable for this . the most widely cable is called ELM327..abundantly available on all online electronics websites,such as amazon,amazool,and ebay
in addition to this hardware you will need a good sotware for retreiving your ca's data,and possibly remapping/retuning your ECU..That way you can change your car's performance in many ways...just google OBD Softwares and there are many...There ia an iphone app which allows you to see and even control your car's various parameters from your phone (since i hate iphone i wont tell you the app).
I bought a cheap cable which partially worked,and i could read the error code . It was P0300 which means that my car's cylinders are randomly misfiring,and there is no straight forward solution for this issue and i may have to get rid of this car..But the cable loses connection with ECU if i try to do anything else , such as realtime sensor monitoring or ECU remapping..i will return the cable and buy an expensive onw
For my car's misfiring problem,The suspect is the HT cables which gives current to the spark plugs..
If anybody can suggest,or comment a solution about the random cylinder misfiring..that will be much appreciated