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engine failed emission test
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matthew37
New User
Nov 30, 2009, 6:25 PM
Post #1 of 2
(1721 views)
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engine failed emission test
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I have a 2002 F150 4.2L V6 4WD. I have had trouble with the engine idleing very rough and poor gas mileage. Overall runs quite poor. I replaced the plugs and wires with no change. Now it failed the required emossions test and I need to find out what the problem is. I have the error codes from the emissions testing facility and are as follows - P0171: System too Lean; P0316: misfire detected during startup - first 1000 revolutions; P0301: Cylinder 1 misfire detected; P0303: Cylinder 3 misfire detected. I would really appreciate some advice on where to begin. Thank You!!!
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Loren Champlain Sr
Veteran
/ Moderator
Nov 30, 2009, 7:23 PM
Post #2 of 2
(1710 views)
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Re: engine failed emission test
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matthew; This has me a bit puzzled. #1 and #3 are the front and rear cylinders on the passenger side. Each sharing a seperate coil pack. Even the lean condition doesn't make sense, since the positioning of the cylinders. Was the engine running this way before you changed plugs and wires? About the only thing that makes sense to me, would be injectors. And, for two of them to take a dump at the same time........Listen to the injectors on those cylinders. They should be 'clicking' with the engine running. Using an ohmmeter, measure the resistance of all of the injectors. The odds are against it, but I suppose anything is possible. If no vacuum leaks are found, resistance is within specs, certain that the plugs/wires are okay, could be that the injectors are plugged or have a poor spray pattern. In most cases, they can be cleaned with a machine. (not the snake oil they sell in cans). I understand that they test your vehicle via OBDII, but some exhaust gas readings would help a lot in diagnosing this.
Loren
SW Washington
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