Throwing in the towel need some help with a p0304

To start with I have searched but have not found anyone having the same problem I am. Most people have had happy endings. However I am not

My truck is a 2004 ford ranger 4x4 with a 3.0 automatic 135000 miles and has been well maintained

The truck has randomly thrown a p0304 and a p0316 in the past and a tune up would make it go away.

This week the truck started flashing the check engine light when coming to a stop, if you reved it up the light would go out. It also has been shaking like a crack head going on a withdrawl at idle. So I read around and found out some people were having injector issues. I put a new bwd injector in and I thought it was fixed, the light has stopped flashing but after a few drive cylcles it returns to stair at me in the face. Lots of choice words were said at this moment of time and its the same p0304. It does not always throw the p0316 when it throws the p0304.

Heres where I stand

I replaced the coil 30000 miles ago with a oem ford one
The truck has new spark plugs and wires (motorcraft) #4 has a newer one less then 50 miles on it
New fuel filter (motorcraft)

I know I have spark and even used a spark tester to double check today.

The fuel mileage seems to be suffering but if I have a dead cylinder I am sure thats why.


I am doing a compression test this weekend but have a feeling it will be bad news. I feel like this motor should be far from worn out.

Last week the intertia switch and connector burned up and almost left me walking so needless to say I am a bit fed up at the moment. I put a news transmission in it about 6 months ago with new tires shortly after. I reallyyyyyyyyyyy do not want to be having mechanical issues with the engine.

Anyways if anyone has been down this road let me know

Thanks

suzuki14258 said:

I am doing a compression test this weekend but have a feeling it will be bad news.

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I think you'll find that will trace your problem. Make sure you do it with hot engine.

How is the oil?

P0304 Cylinder 4 Misfire Detected- I would double check just to be sure everything is okay with that injector/plug and all the wiring for it for cylinder #4. Can't Hurt.

P0316 Engine Misfire Detected on start-up- We can safely assume this is caused by the #4 cylinder, giving the code description it makes sense that it doesn't always show up.

You said the inertia circuit and plug burned up? Have you looked into this? Maybe your fuel pump is starting to overload the circuit. That can't really be linked to just cylinder #4 misfiring, but low fuel pressure will cause problems either way.

As stated a compression test is your best bet for ruling out the engine itself, and weather or not its an electrical/other issue elsewhere.

03ranger4x4 said:

You said the inertia circuit and plug burned up? Have you looked into this? Maybe your fuel pump is starting to overload the circuit. That can't really be linked to just cylinder #4 misfiring, but low fuel pressure will cause problems either way.

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It would burn up the relay first. The inertia switch is another power source directly related with the fuel pump relay that switches it on (so to speak). So it either works or it doesn't.

What spark plugs did you put in it? Did you go with factory plugs, Platinum, Double Platinum? Also did you do spark plug wires? What about fuel pressure?

True, I didn't even think of that, the inertia switch would likely kill the fuel pump relay power then the power to the pump itself directly.

adms08 The oil is full and needs to be changed soon (500- 1000 miles)

03ranger 4x4 I think the intertia switch burned up do to a bad connection and caused it to get really hot and melt. I replaced the connector and switch with new oem parts. Like you said though I think it should have effected all cylinders.

I have not checked the injecector itself because i dont have the tool to do that. I wish my truck would have done this when I worked at the dealer! We had some stuff that would have really came in handy. All the wiring looked ok when I took the intake off and the connector and pins looked great.


explorin94
I used factory plugs, motorcraft platinums, the wires are less then 5 months old and have less then 6000 miles on them. They are motorcraft also. I have spark at the coil and all the way to the spark plug it self. I have not checked the fuel pressure yet.



A little bit of a update. I have been driving the truck for atleast 6-7 drive cycles and have not been letting the truck idle unless I have to. If i do i put in neutral and idle up. If its a extended period of time I turn the truck off. It may be idling to low and need to be adjusted?? The check engline light has not came back on since I have been doing this. Im still doing a compression test and a fuel pressure test this weekend.

What is the normal idle for this truck? When it warms up it drops to 650 but if I hold it at 800 or higher its great and smooths out.

Well bad news atleast for me, I feel like throwing my ford hat in the trash at the moment

It failed the compression test on that cylinder, the rings are bad and it didnt do to well on a leak down test either.

1 160
2 150
3 115
4 115 this cylinder went to 175 when adding oil and didnt pass the leak test
5 140
6 135

The check engine light came back on right before the test

Sooooo I chasnged the oil and added some lucas oil additive for the time being and will hopefully get a few more months out of it.

After driving it 10 miles home i let it idle for about 15 minutes and it ran like new then the engine started shaking really bad like it has and flashed the check engline light. Thats the longest I have been able to idle it for the last 2 or 3 weeks though.

suzuki14258 said:

I feel like throwing my ford hat in the trash at the moment. It failed the compression test on that cylinder, the rings are bad and it didnt do to well on a leak down test either.

4 115 this cylinder went to 175 when adding oil and didnt pass the leak test

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My truck is a 2004 ford ranger 4x4 with a 3.0 automatic 135000 miles and has been well maintained

Click to expand...

That's disappointing, especially for so few miles. Number 3 doesn't look that great either.

To give you an idea of what these readings should be here's my compression check at 11,350k

1 - 190, 2 - 190, 3 - 185, 4 - 185, 5 - 192, 6 - 185

I should take it again soon. I have a 95 Camry with about 190k and all four cylinders measure 170psi, that's only 8psi below factory spec. This is my first Ford and I'm still evaluating it. 135k is no time to be doing an engine rebuild.

I agree its depressing. There was a kit I was excited about getting to rebuild it and take it to a 3.3 until I saw the price. Its over 3 grand so thats not happening. I will just keep my eyes open for a wrecked truck or park mine and have it rebuilt when it gets worse.