I have a question in regards to a 1997 Ford F-150 (f150) V8 4.6L with misfire code P0304. 120,000 miles, 4x4

This all started after I ran a bottle of Gunk 5 Minute Engine Flush. I don't have anything negative to say about the product; just stating when this started. During the same time frame I had also replaced the water pump, flushed and changed coolant, replaced serp belt, ran Seafoam in the tank (One 16oz bottle), ran Seafoam through the brake booster (1/3 bottle; never stalled engine; shut off immediately; followed instructions), replaced thermostat, and also replaced the clockspring.

Before you ask, I did the Gunk treatment exactly how it instructs on the back of the bottle. After the Seafoam (in the tank and brake booster), the truck ran amazingly. It was quiet at the stoplight, and had power back that I hadn't been able to realize for a couple years. The directions on the Gunk state that I should drop the oil pan if I have more than 50,000 miles. On the '97, I would have had to raise the engine, or lower the front axle to do it. The back of the bottle also states that vehicles over 100,000 miles should get a second treatment, so instead of taking the oil pan out, this is what I did:

1) ran the engine for 5 minutes with Gunk
2) Changed oil and filter
3) Drove less than 30 miles
4) Ran second (2nd) bottle of Gunk
5) Changed oil and filter
6) Ran it at idle for about 7 minutes
7) Changed oil and filter (yes, again)

So, I still have the P0304. I decided it was time to change the plugs and wires. Replaced plugs with new Motorcraft sp432. Replaced wires with a set of Autolite. The code came back (P0304; misfire cylinder 4). So, I picked up an injector; but before installing, I swapped the old 3 and 4 injectors with the old 1 and 2- and vice versa. Drove for 20 miles and the code came back again.

Since this 97 does not have COP (Coil On Plug), it just has the two coil packs and so I had asked some questions. The consensus is about 50-50 that a faulty coil would affect two cylinders (not only one); since it's a coil pack it has a primary and secondary inside the coil, and if either were faulty it could not only effect one cylinder. I have not switched packs.

Someone said it could be an O2 sensor, but when I asked more about this everyone else said it couldn't be. The same person that said it could be an O2 also said it could be a bad Cat (Catalytic Converter). No one besides him thought it could be a bad cat.

Talked to a shop, and not the Stealership. Shop said it could be compression but he wouldn't do a test on Fords because (he said) the shop's gauge wouldn't go to the bottom of the spark well. I think it may have been that they find the cowl and heater core hoses to be in the way for their compression test, but I don't know.

I have recorded some KOER data, if that would come in handy. I also have a OBDLink coming in tomorrow (with any luck on USPS), and the Torque Pro Android App, so every bit of data from the OBD II will come to the bluetooth on my computer, or my phone. If any values are needed from me to help you help me diagnose this problem, I will post them.

So, a misfire on cylinder 4 after plugs, wires, changing fuel injectors, Gunk Flush x 2, three oil changes, seafoam brake booster, seafoam in tank...etc.

I have rough idle now like never before. It could be worse, but you can't keep a steady hand in the truck. Loss of power (very evident at times, other times the power seems fine). Urine Poor Mileage (like 5-8 per gallon), hesitation, and a blinking SES.


In advance,

A Kind Thanks.

 

I know you swapped injectors , but is there power to it? If you cant back probe it, with a long hose in your ear and the other end on the injector can you hear it clicking?

Does the engine change if you pull off the wire to plug 4 running?

 

@kbsupercrew: Swapped coil packs, and the code came up again. Flashing CEL. I failed to mention that I have a lot of water dripping out of the exhaust at idle. It almost looks like brown smoke coming out, along with white smoke. I also have white build-up in the oil fill spout. I took some photos of it, and it looks very white, but when I swiped my finger in it the color is apparently more of a light tan color. I had a shop perform a test to see if I had a blown head gasket and there is no exhaust gas coming through the Rad. I don't know if it's normal, but when I take the dipstick out, it appears to be a bit of smoke coming out of there; as well as coming from the oil cap when opened. Also, after all this, I noticed oil has recently been leaking out of the oil cap, or the housing around it. I took some photos, and can post them on photobucket if you want. Lastly, I put my hand next to the tailpipe and I thought it smelled like coolant, though I am not losing any. I do make a lot of trips that are frequently just a few miles in either direction.

As per your instructions, I used a hose and could hear the injectors clicking. (Excellent idea, by the way.) I listened and heard all of them. I went ahead and pulled the plug. Stuck a smaller diameter phillips into the boot and grounded it to the throttle spring. Excellent spark. Next, I took out the plug and put it into the boot. That too had excellent spark. I wimped out on pulling the plugwire while it was running. Alternatively, with the engine off, I pulled the boot and set it on the cowl then started it up. The engine seemed to "maybe" run a little more rough, but no drastic changes. I listened for any changes for a couple minutes, then shut it down and installed the plug and seated the boot. Started it up and listened for any variance, but didn't hear anything abnormal.

Would you recommend doing a cylinder pressure test? If so- if you know the least expensive way to do this, I would like to know. I believe I can just go to O'Reilly's, NAPA, or Autozone.

Thank you for helping me out.

 

You should be able to use any compression tester you want to....was the spark blue or orange-ish when you checked it? A weak spark will cause your issue....i would lean more towards the coil pack...

 

@Big_redneck3100: I swapped out coil packs (left to right- right to left). The spark was large, white and blue. Very strong.

 

Two items come out of your posts.
One is that the flashing SES lamp is telling you fuel is being injected into that cylinder and passing through to the cats on bank 1 where it lights off in the 700 degree cat operating temperatures. Let this go to long and it melts the front cat.
.
Two, the excess water in the exhaust suggests coolant is killing ignition in that cylinder.
Look for a head gasket issue between cylinders or between cooling and that cylinder.
Since the spark may be inhibited by the coolant, there won't be any exhaust in the coolant due to that cylinder that is not firing.
Look close at the spark plug for signs of coolant on the tip.
Good luck.

 

I would do a compression test first, and compare to another before taking on a head job ,btw when you looked down the oil fill did you see a lot of sludge? I was just thinking of build up breaking loose after your gunk treatment causing your valves not to seat right, just an idea

 

@Bluegrass 7: Nope, there is no coolant on the plugs, wires, or in the plug well (before taking out the plug). The exhaust water is only water. I smelled it, and even tasted it... It's only water. I bought a compression tester and will be doing that within the next day or two. At this point, I hope it is a a gasket leakage between cylinders.

I read where this other guy had the same issue, he cleaned his upper intake, and throttle body, and the carbon had blocked the passage to #4 cylinder. He stated that 5 cans of carb cleaner fixed his problem. is there any chance of this being the case?

 

@Kbsupercrew: I'm about to do a compression test in the next day or two. Yes- when i looked down the oil fill, I do see a lot of sludge. It is white, and light tan in color. If my valves are not seating right, is there anything that I could pour down into the cylinder to soak into the valves to seat them correctly. I understand it would probably be an issue under the valve seat. When I do a compression test, and if it is off considerably (compared to the other cylinders) would I know if it is a valve?

 

Any chance that, because of the location, that maybe the plug wire terminal didn't actually lock onto the spark plug ? It's real easy to slide the boot down the plug, but keeping it straight, all the way until you hear the click isn't always so simple.

I know the code says #4 misfire, but I think that's the waste spark ignition. My '99 is the same thing. The misfire might be on the other cylinder that fires at the same time.

Dave

 

@Dave G. None of the other cylinders fire at the same time. I'm not positive, but I think my firing order is: 1,3,7,2,6,5,4,8. The spark plug is certainly seated in the boot. You're right- that #4 cylinder is a B!*$# to put the boot on plug, but I've taken it on and off probably 15 times. I'm certain that isn't the issue. P0304 is a misfire for the 4th cylinder. If it was a misfire on another cylinder, wouldn't it be P0305, 1, 6, etc... just something different? I will look at the other plug wires to ensure they are all seated.

 

@Dave G.: I just checked them, and all plugs are seated correctly.


I read where this other guy had the same issue, he cleaned his upper intake, and throttle body, and the carbon had blocked the passage to #4 cylinder. He stated that 5 cans of carb cleaner fixed his problem. is there any chance of this being the case?

 

There's always a chance, but, the problem started with doing the initial engine flush, and went downhill from there, correct ? So I'm assuming that something that was installed, based on the #4 misfire, isn't working.

A compression test seems to be called for, and engine monitoring while actually driving down the road.

Dave

 

Until a compression test is done everything said here so far is pure guessing. Replacing parts before doing a compression test is costly, a waste of time and stupid.

 

You should check the resistance on the coil packs, especially the one for cylinder #7-4. Might be that simple. It could run fine at idle and trip the code with any sort of load.

You ignition does fire two cylinders at a time. The coil is arranged in the pairings. 1-6, 3-5, 7-4, 2-8. By the firing order, whichever cylinder is suppose to fire, it gets the majority of the spark, and the rest fires the paired cylinder which would be on the exhaust stroke by then.

No unusual valve train noise from #4 area of the engine ?

Dave