1. MAF sensor P0120 code. With the engine off and the key on, unplugged from the sensor the plug has 11.9v at ignition pin to battery ground. I have.5v at the MAF sensor signal on the plug pin. Both are in spec value. I did a continuity test between the ground pin on plug and battery ground and it is good.
I’ve taken my whole air intake units off my other 97 & 98 GMC Yukon 5.7 engines that I drive with no problem, but come up with the same issues. So, I don’t believe it is the sensors. I replaced the Idle Air Controller on the carb and cleaned the port.
2. My scanner shows me that the #6 cylinder is missing. I clip my timing light on the wire and watch it flicker. It appears to me it is flashing at a steady rhythm. I pulled the wire off plug and grounded it. It was firing showing the same. I ended up replacing all the plugs wires, rotor, and cap. It still shows 6 as misfiring.
have the same problem?
Tuesday, April 12th, 2016 AT 12:12 PM