@spectra, @ser_gtr, @star2
I've checked the knock sensor, crank shaft, cam shaft and MAF outputs at ECM side (in accordance with recommended values in the manual).
MAF is giving 0.8V on ECM side when at idle, it is supposed to be in between 1-1.4V.
Camshaft output is also not in accordance with desired range. Knock and crank seem fine.
Saqib Bhai, though crank and cam are same, the manual says we should check AC voltage for crank and DC voltage for cam. Is it really so or there's something wrong in the manual???
Secondly, at the MAF pins, the output is fine. But at the ECM side, there's some drop.
As per the manual, if abnormally low voltage is detected at ECM from MAF, it will enter the failsafe mode. RPM will not go beyond 2500 (which indeed seems the case here).
And also from other internet sources, if Cam sensor is bad, fail safe mode will be activated, with ignition timing value set to whatever last value was received (which in my case is set to extremely retarded value).