Discussion in '1998 - 2011 Ford Ranger' started by Chrisrowan, May 12, 2020.

  1. Chrisrowan

    Chrisrowan New Member

    Ok I have a 2000 4.0 4by4 xlt when I got the truck had the engine light on so I took it in it was upstream o2 sensor. Awesome fixed ran good for about a week. Pull out of work one day and boom bucking and jerking when I get in the throttle. This has been going on for about 3 weeks and I’m going broke. It finally threw a code po304. Ok I have done plugs,wires,coil pack,mass sensor,ips sensor,tps sensor, all 3 o2 sensors, fuel filter,checked fuel pressure it’s good. Tried carb cleaner spraying all vacuum lines I can see nothing I cleared the code and took 6 days to pop up again but was still bucking please help running out of money and patience with it love the truck and it’s probably something stupid but I can’t figure it out.
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  3. Jeff0266

    Jeff0266 New Member

    Hi,I looked around and found your problem looks to be a misfire in the 4th cylinder somewhere.

    • Worn out spark plugs, ignition wires, coil(s), distributor cap and rotor (when applicable)
    • Incorrect ignition timing
    • Vacuum leak(s)
    • Low or weak fuel pressure
    • Improperly functioning EGR system
    • Defective Mass Air Flow Sensor
    • Defective Crankshaft and/or Camshaft Sensor
    • Defective Throttle Position Sensor
    • Mechanical engine problems (i.e.—low compression, leaking head gasket(s), or valve problems

    When diagnosing a P0304 code, it is important to record the freeze frame information and then duplicate the code setting conditions with a test drive. Pay close attention to the engine load, throttle position, RPM, and road speed because a P0304 (which is a specific misfire) can sometimes be difficult to detect. If the Engine System has a Misfire Counter for specific cylinders on the Scan Tool Data Stream, pay very close attention to the cylinders(s) named in the misfire code(s).

    If there is not a Cylinder Misfire Counter, then you might have to switch components—such as coils, spark plugs, etc.—in order to isolate the root cause of the misfire. It is also important to note and record any other codes because the engine may be misfiring due to the failure or malfunction of another system or component. An ignition system problem is usually the cause. The computer has detected a 2% miss in between 2 cylinders. If it was any more the CEL would blink if I'm understanding this right. A lean misfire can also be the problem. Could b a sign of a failing fuel pump,a clogged fuel filter or even a leaky intake manifold gasket can do it. Shoot,it could even be a vacuum line off or damaged. Hope this helps and if not then I hope you learned something you didn't know haha.

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