Ford/Mustang :: 1997 - Getting Error Code P0304 / Cylinder 4 Misfire
Apr 6, 2013
1997 Ford Mustang 4.6L EFI engine with 67K miles. The engine is actually now in a Factory Five Roadster. It sat on a stand for 5 years but runs well now with the exception of the code. I keep getting a code P0304 (cylinder 4 misfire) and I've checked the plug - the code seems accurate; it is misfiring.
Things I've tried:
1)swapped plugs,
2)this is a dual coil engine so I've swapped coils,
3)the #4 plug is the longest sparkplug wire so I've gotten high-performance wires,
4)heavily grounded the AL head,
5)put dielectric grease on the plug,
Still, ONLY cylinder 4 gives the misfire.
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I left my chevy s-10 truck sitting over the christmas (23/24/25) and it was really cold outside and when i got back i started getting a P0304 (Cylinder 4 Misfire). I replaced the spark plugs and spark plug wires. May be the cold would cause this to happen? I think I've noticed the trucks fuels efficiency drop over the past month). May be the fuel injector(s)? Is the s-10 TBI or does it have fuel injectors for each cylinder?
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2006 PT Cruiser Touring Ed. The engine light came on 2 days ago, had it looked at today and the error code p0304 "cylinder number four misfire" was diagnosed. What causes that and what would need to be done to fix that problem?
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1997 Grand Prix 3.8 N/A 181,000 ... I have been getting a misfire only on cylinder 4 which has become more frequent. It "only" happens after the car has warmed up and I turn it off for a few minutes, for instance going in to pay for gas. When I start, it immediately starts to miss but as soon as I hit the accelerator it evens out and runs great, every time. I replaced plugs and wires two years ago with stock.
Upper and lower intake manifold gaskets were replaced around 110,000. All three coil packs have been replaced with original GM packs. I replaced my EGR valve last year due to the original was sticking. My throttle body was cleaned about four years ago. I've seafoamed through brake booster and the rest in gas tank.
I'm stumped that it corrects itself right away by giving it gas. The SES light always come on but goes off on it's own after a few cycles.
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I know I can fix this problem, but my question is which cylinder is #4? I don't see it marked on the engine. The counter guys at both my local parts supply stores (whose initials are A and O) can't even look it up for me. If #4 is on the front of the engine, then it's an easy fix. If it's on the backside, then the intake manifold has to come off to get to the plugs and coil packs. It's a bit more labor. I can do it, but I'd rather not have to.
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I recently bought a 00 Excursion v10 2wd everything looked right no major problems. I noticed it has a rough idle and i thought it could be the EGR i went under the hood and there's no EGR in sight. I plugged the OBD reader to see if it would give any codes since the there was no check engine light on and wanted wanted to make sure it worked, It showed a P0304 code its Cyl4 misfire i checked plugs/coils and i noticed there's a little insert inside Cyl4 plugs hole in the head that it has the plug screwed on. I decided to change all the plugs and the coils and i still have the rough idle and code i can hear a ticking noise around the engine in the passenger side.
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6.0 .... Have a code Po3o4 Cyl 4 misfire. I pulled the valve cover to remove the injector and found the right half of the rocker mount and rocker arm laying in the head. What may have happened?
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So, my 2003 F150 4.6 that I just put back on the road after a four month break is running like crap. I took it off the road for the winter because it was missing (no codes) and didn't feel like dealing with it then but after running it for a day the CEL comes on. It shows the following:
P0304 - hoping it is a coil pack
P0456 - pending. Gas cap?
P0171 - pending. One bank too lean?
Does the 171 code possibly have to do with the misfire in Cylinder 4? I know it is impossible to tell yet but am hoping there is a potential connection.
Before I parked it in January, it was running a bit rough and stumbled on acceleration but never would show a code. Now all this. Going to change the coil first, tighten the gas cap, check for leaks and see what happens but is there anything common on these trucks that I should also be looking at?
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Have '01 SE. yesterday I got a misfire in cylinder 4 (code P0304) the service light blinked on and off 3 to 4 times than stayed solid. changed plugs and boots about 1 to 2 months ago, didn't change coils and they r not in the best shape but didn't have money to replace at time. So I replaced the coil for #4 and it still runs rough with code, plug has some ware but looks fine.
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2000 Jetta GL 2.0 AEG. I am receiving the P0304 which I have identified as Cylinder misfire #4. I read on some previous posts that I cannot be the distributor because if it was I would be receiving misfires on two cylinders. The spark plugs are OEM NGK and have been replaced recently.
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Well, I have a big problem on prius 3, the problem is that it has a big and I mean a big body shake when I decelerate above 30 mph or slowly accelerate above 30 to 50-70 mph, when I fully accelerate, the body shake disappears. When the body shake occurs MIL comes blinking and DTC P0304 comes but not always, but the shake is only when the coolant is hot.
On the other hand, if the MIL is not on with the tester it can be seen that the cylinder 4 has misfire margin, only cylinder 4, every time. Now what I have done is to exchange the injectors, problem remains on cyl4.
-replaced the coils, problem remains on cyl4,
-clean the EGR, problem remains on cyl4,
-opened the engine to see the valves, cylinders, pistons, exchanged the ring set,problem remains on cyl 4,
Replaced the wheels, the problem is still there, now I want to replace the drive shafts.
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My 2003 Silverado 5.3 has an intermittent CEL. I plugged in the reader and found code P0304, misfire #4 cylinder. I changed the coil, swapped the spark plug and wire from #2 cylinder to see if the code would follow. Nope, didn't follow. I swapped the injector also, same results. My daughter decided to borrow the truck and drove it so low on fuel that the low fuel light came on in the drive way. I added about 4 gallons of fuel and now the light went off. I started the engine after a jump start, and the engine really runs rough and now won't stay running. I am thinking that the fuel filter is probably needing changed because of how low the fuel.
I haven't checked the fuel pressure yet and will do that today. Now, what really puzzles me is the intermittent part. Sometimes it will run with no problem, but then the CEL will come on and the fun begins. The Chevrolet dealer says it's caused by the valves turning in the head and when it reaches a certain spot, it detects the misfiring #4 cylinder resulting in the CEL. If I pull in the driveway with the engine missing, go back out in a short time, start the engine and it runs fine. Same thing if it's running fine and I can start it and the CEL blinks and it begins missing, but may stop and run fine. I am stumped and not so sure about the turning valves.
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Went on a trip Sunday, and i saw my engine light come on after i put gas in the car. I pulled over, re-checked the gas cap, and it was fine. Car felt fine.
When i got home, i used my OBD2 scanner, and got the error P0304 Code - Cylinder #4 Misfire. I cleared the error and drove the car some more, no issues.
Yesterday, my wife took the car and she said it was hesitating and sputtering, but the light hasn't come back. I have an appointment at the dealer tomorrow, the car has under 80,000k, so the warranty should kick in.
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(This is a continuation of a previous thread: [URL] ..... )
I have a 2005 Nissan Sentra with 75,000 miles on it. Several months ago (see above link) the check engine light came on with a P0304 cylinder 4 misfire code. The only symptom appears to be a rough idle/shaking every 3rd or 4th start for the first 10-15 seconds, but runs smoothly afterwards. My mechanic replaced all my spark plugs (I had new plugs put it at 50,000 miles for the same issue) of which the one from cylinder 4 was worn down much more than the rest. The problem persisted so they replaced my fuel pump and fuel filter and switched the spark coils from cylinder 4 to a different cylinder, but the code still read cylinder 4 so it wasn't the coil. That was back in October.
I took my car back in last week for the same problem and without starting my car (because the problem is worst on the first start) they pushed my car into the bay and did a smoke test, no leaks in the fuel lines. Then they checked the cylinder and said that there was "excess" fuel in the cylinder and replaced the fuel injector. Then after ~3 days the check engine came back on with the same P0304 misfire code. Previous repairs/diagnostics rule out spark plugs, coils, fuel pressure, and injectors.
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The car has an obvious misfire and the scanner says its Cyl # 8. I tried the "italian" tune-up and under heavy throttle the miss goes away. I swapped coils and the miss stays with Cyl # 8. I pulled the injector, and can't see anything wrong.
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So I dropped my prius off to get looked at for error code p0301 number 1 cylinder missfire. They ruled out Spark plugs, coils and fuel injector. What else is ther? Also could it be the battery or even gas?
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Getting error code p0302, misfire in 2, pulled the plug and had oil on the treads and on the lower part. My guess is the valve cover gasket, but I'm not 100 percent sure.
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I was driving along and the engine started missing really bad. The whole car was bouncing around. At first I thought I had a flat, but when I stopped I noticed it was the engine. I checked the error codes and got 16684 and 16686 --- Random/Multiple Cylinder Misfire.
I had a problem recently with the vacuum hose broken and was causing an error code. Replace the hoses and it has been fine. Checked to make sure that the hoses were secure and they are fine. Doesn't seem to me to be related. So many problems for a car with 57,500 miles
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So my 99 F-150, 4.2L started throwing a code a few weeks ago, P0306 #6 Cyl Misfire. This thing has got 238,000 and has been the most reliable commute vehicle I've owned.
Today I changed all the plugs and wires (they were due anyways) which didn't resolve the issue. After clearing the code, got about 3 miles out and it came back. Running SeaFoam through the system on this tank as well, but I'm leaning towards an EGR blockage like what is described here:
Sparky's Answers: 1999 Ford F150, P0306 Misfire Cylinder #6
I was about to buy a new coil pack but I'd rather not continue to throw parts at this, as I've read many others do with this same exact situation, only to end up with the same code. I've replaced the coil pack once already a few years ago when I lost a cylinder on the way to work.
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My 97 F150 through a CEL Tuesday night P0301 so I picked up a new plug because it's cheap and simple, but that didn't do anything. Spark plug wires are about 3 months old, I also swapped injectors between 1 and 2, and misfire stayed with cylinder 1. It also gained a tap when the misfire started but only above idle, but it doesn't sound like a rod knock.
I also noticed if you unplug injector 1at idle it taps/knocks 3 or 4 times, however if you unplug any of the others it doesn't do that. I checked and I definitely have good spark from the plug. I plan on picking up a new compression tester tomorrow since mine never was returned. If you take the oil fill cap off it doesn't have any blow by at idle, however if you rev it you get a quick cloud out of it.
I thought about picking up a kit to check the injector pulse.
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I have a '98 F150 4X2 extended cab with a 4.2l with 233K on it. I have no problem with drivability when I drive 5 miles to work. However, a couple of weeks ago when I had to drive 15 miles to the liquor store to get what I needed (I live in a dry county) I got back into my truck, started it and drove of. It drove like crap like I lost a cylinder. Drove it back home those 15 miles, let it cool off, put my scanner on it and got a PO304 code and I think a PO174 (bank 2 lean) code. Went to the #4 cylinder and found the plug had loosened up.
Tightened it back up, cleared the codes, and went through my normal weekly routine of driving to work with no problem. Made a booze run the next weekend and the same thing happened. Limped back home and found another PO304 code. Found the plug to be tight and in good condition but changed all the plugs since they were cheap copper core and had 20K on them. The wires only have 20K on them, too. Installed platinum plugs, drove all week 5 miles to work and back just fine. Made another 15 mile run yesterday and the same crap happened all over again after I got out of the store and drove home.
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