Grand Prix :: 1997 - Code P0304 - Misfire Only On Cylinder 4 Frequently
Dec 29, 2014
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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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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Driving last night and my 08 died after searching I found the ICM fuse was blown. I replaced the fuse and now it has a misfire on cylinder 6. I have changed the coil with no luck. I replaced the plugs and wires about 2 weeks ago and I don't find any problem with the plug or wire. I checked at the coil and there is no spark at all on cylinder 6. I was thinking the ICM is bad but was wanting some opinions.
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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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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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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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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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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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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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(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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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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2000 Grand Am GT with 3.4 and 150,000 miles. Car keeps throwing code P304 - cylinder 4 misfire. The main issue is the light and needing to pass emissions test. It has just recently had new plugs, wires, and injector #4.
The fuel pressure regulator was replaced about 3 years ago because it was leaking fuel, enough to smell while driving the car with windows rolled down. Shortly after the fpr was replaced, the acceleration problem seems to have started, either by coincidence, or improper installation. The light/error has been occurring for quite some time, about the past year or two. About a year ago, the car was also throwing a random misfire code. I am not positive if both codes were being thrown at the same time, and when exactly the P304 started.
The crank (or cam) sensor was replaced and worked with the issue for a short while (removed codes/light for maybe a few months?) Before the sensor was replaced, the car would stumble at very slow speeds, 0-10 mph. Also replaced Idle Air Control valve last year. The car would sometimes surge on semi warm starts (not cold, not 190-200) between 500-1000 rpms. The surge would be worse when I had the blower running or the rear defrost on, down to 200 rpms at times.
Currently, the car runs perfectly fine for me, except when trying to accelerate on highway ramps. Its firing somewhat when you step on the pedal, but lags and takes longer than normal to accelerate up to speed for merging with traffic. Drove the car after new injection and said it runs fine while driving, but the misfire seems to be mostly or only occurring at idle.
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I have a 95 Grand Prix 3.1L and I can't turn my key. You can put it in and take it out, but it won't turn whatsoever. It's stuck in my driveway and I've tried just about everything to get it to turn.
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I have a 97 grand prix GTP that I am replacing the ignition switch on. I am having trouble locating the small hole on the key cylinder that I put an allen wrench into to release the key cylinder.
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1997 Grand Prix GT N/A. 175,000. I keep getting this code about once every two weeks. I'll clear it and doesn't come back until then. I've had passengers in the back seat smell gas so I'm suspecting the vapor canister. Would a leaking canister set this code off? I checked all the vacuum lines to the purge solenoid and seem fine. Is the canister in the drivers side rear wheel well? I need to get in there and check if it's leaking. I'm having no driving issues however my gas consumption seems to be a bit more than usual. I checked the FPR and no fuel contamination.
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2000 Grand Prix GTP has code P1629, car will run for 3 sec with black master key and then die. Security light in dash is flashing when this happens. Tried the 30 minute relearn for PK3 with no luck. It will start and stay running with the grey Valet key which is perplexing to me. As of right now I am siding with replacing cylinder and ignition switch after everything I've read on the subject.
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I bought my 2001 Grand Prix with a 3.8 liter (non supercharged) earlier this year. Within the first month, the check engine light came on with a P0410 code. Took it to the shop here at the auction that I work at to get repaired. He ran the diagnostics on it and found that the air pump wasn't working. He pulled it out and it was full of water, due to the air inlet being so low. So, he replaced the air pump and re routed the air inlet so that it was higher up into the engine compartment. That same night, the light came back on, so I brought it back in the next day. The relay failed and popped the fuse. Replaced both, and the light was off for a full day.
Got ready to take it in for its emissions test today, and the light came back on again. The air pump is not working, again. Turns out that the previous owner had replaced the air pump twice (once with aftermarket, and once with an OEM unit) because of the water build up and freezing the first time. I am not aware of any GM service bulletins, but there has to be something that is taking out these pumps. The only things not replaced on the secondary air system is the lower check valve and solenoid. So, what could be causing the pumps to fail prematurely?
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1997 chevy k1500 ... I have a misfire on cylinder 3 that i cannot figure out the cause. The idle is rough, backing out after starting is very rough, it seems to pick up at higher rpms but once the truck upshifrts to the next gear it shakes like a leaf in fall. within the past year the engine was rebuilt all new seals a new fuel pump, new injectors, new everything practically. so far i have done the following:
compression test results:125-130psi
fuel pressure test results: 50psi once primed, 50psi with engine running, no immediate pressure loss after engine is shut off
new spark plug wires
new spark plugs
replaced all four o2 sensors
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