I used fuel gauge to test fuel pressure; 42-44psi, I guess its ok?
Also removed ect sensor, checked resistance while applying heat, noticed the resistance reading dropped 300 ohms, so I guess the ect is ok? Next i'll check ignition timing w/ timing light, not sure what that will prove, if some sensor or sensors are bad and not sending correct infor to ecm to timing could be adversely impacted. I'm going through process of elimination trying to isolate. Compression test was good, fuel pressure good. I unplugged tp sensor, placed potentiometer across it to vary resistance and revved engine to see if engine would stop bogging down. I did this to try and determine if the tp sensor was bad. It didn't seem to improve anything. Idle is smooth, as I rev up the engine until it hits that boggy position at about mid throttle and engine starts to die. I've performed voltage drop tests on all grounds of ecm, found nothing. I've tried covering throttle valve opening while revving engine, engine would only die if I totally blocked throttle, naturally ( NO VACUUM LEAKS?). Because fuel pressure tested ok, can I assume its the engine is not starving for fuel? But, its the sensors that feed the ecm, and the ecm then tells what fuel mix to add to the air. Circular reasoning. Ecm is closed looped system how can one diag? What else should I be checking?
Wednesday, February 2nd, 2011 AT 6:23 AM