hard start & engine codes
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Freshman User
Joined: Jul 2001
Posts: 31
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From: southwest pa
hard start & engine codes
1996 F150 - 6 cyl. wouldn't start this morning. AAA finally got it started. Engine would turn over and try to start. Its been very cold here in Southwest PA lately. After truck started, check engine light came on. Codes P0172, P0174, P1151. Autozone said P1151 was mass air flow sensor. Would truck not start if this was faulty. Is it hard to replace this sensor.
Lead Driver
Joined: Nov 2002
Posts: 9,557
Likes: 44
From: Concord, NC
Try cleaning the sensor before you replace it. It could be dirty. Do you know the code definitions? I want to say that they are O2 sensor faults for lean, but I don't know for sure. Check the wiring to the MAF sensor and clean the wires inside the meter gently with a q-tip with some rubbing alcohol.
Lead Driver
Joined: Nov 2002
Posts: 9,557
Likes: 44
From: Concord, NC
I don't know if it would make it hard to start or not, but I'm pretty sure that it would cause the O2 faults. Double check the wiring to the MAF as well as cleaning the sensor elements inside. There should be a +12 Volts (should be a red wire), a ground wire (black), and a sensor signal and a sensor return wire. You should have .5-1.5V between the signal and return wires at idle.
Lead Driver
Joined: Nov 2002
Posts: 9,557
Likes: 44
From: Concord, NC
Have you checked fuel pressure? If fuel pressure was low, injector pulse widths would go up, and the mixture would run lean. Low fuel pressure or fuel pressure that drains off too fast can cause hard starting. Try cycling the key on and off (don't start the engine yet) several times before you crank the motor next time you try to start it, and see if it starts any quicker.
