Ford F-150 - 1997-2003 :: CEL Codes P0304 / P0456 / P0171 - Misfire On Cylinder 4
Jun 1, 2014
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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P0306 (ok #6 missfire) with P0171 & P0174 --- Do I chase electrical or fuel or both. Afraid to assume anything but probably would normally address the misfire electrical first.... Don't want to go down that 'primrose path' if others have been there first!
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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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2001 f 150 5.4 liter with it being code pops up saying cylinder one misfire, I've charge coil and spark plug ran great for awhile now starting to act up again. Got coil check and says still good and look at spark plug and looks still in good shape being just replace two weeks ago. It's running fine but if it sits over night and I get in and start it and begins to shake when I but it in drive and don't even need to move the truck just place it in drive with foot on break. I drive it awhile and it stops and runs fine?
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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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Here are the codes I'm getting:
P0455 - large evap leak
P1451 - main control (evap canister)
P0306 - cylinder 6 misfire
P0174 - bank 2 lean
are these all related? Or two separate issues. I have replaced all the evap lines with new lines. I have a new egr valve, and exhaust manifolds, and what should I look at 1st
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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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2003 F150 v6 2wd 170k ... For a year I've only had codes P0171 and P0174 (lean bank 1 and 2). I was told it wouldn't hurt anything... I think now I should have taken care of it.
Anyway 3 weeks ago my truck started running a little rough. It was sputtering and had trouble getting up to speed, sometimes also the air switches from vent to defrost until switch gears and rpms go down. It gradually got a lot worse over 10 days while part was otw. A week ago i changed MAF and cleaned the black thing it's inside of. It started running better but still not good. I pulled my small trailer 2 days ago and it got worse after dropping the trailer.
Today checked codes at AZ and lean codes are gone and have p0304 (#4 misfire) and p0316 (crank sensor problem). Is this related.? Also Right before all the trouble I changed battery and alternator. Also i read online that MAF needed 2 weeks to relearn the way I drive to get correct gas/air ratio? Is that correct?
Also I read so many different things I needed to do during installation... Some say I need to turn key to the on position after unplugging old MAF then plug new one in... turn key to on position 10 times, Rev up engine, drive it rough for the first 2 minutes... etc. Is there a correct way to do it or is it vehicle specific?
Should I start by changing spark plugs and coils? The guy i bought it from and trust said he changed spark plugs right before I bought it. Will it ruin truck if I drive it? I've read so much but everyone says so much different things on the same topic. I'd what to start with or if this is related.
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Ok, so this past week i towed my 72 f250 to IL from CA. 2100 Miles. 6100#s with the trailer. No problems at all. Got about 9 MPG too the whole way. Ok, so here is my problem now. As some of you may know, IL just got about a foot of snow. Its all slush at this point. I am living in the country right now so i drive thru alot of it. Ok, now you know the back story, today i drove the truck to my brothers house, put it in park and bam! check engine light came on. About a half hour later i drove it to AutoZone and had them check the codes. Here is what they pulled.
P0705
P0171
Need to know what to replace. I have to drive it back to CA in 4 days.
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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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So I have a 1997 ford f150 v8 4.6 2w... I got codes p0171 and 174 my truck seems fine till the idle drops, it's weird when I have it on park it's fine if I turn the wheel left the idle drops when the ac turns on the idle drops and it's wasting crazy gas. Where should I start first in finding this problem?
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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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2001 F150 5.4L Triton Motor. Everything seemed o.k. then got the Engine Service Light. Checked with reader and above codes only appeared. Read numerous articles/videos and pulled the PCV hose/boot assembly and replaced the whole thing with oem part. Visually checked for disconnected tubing = none found. After this and with the new hose assembly in place I performed a reset. With the scanner still connected restarted engine and read values: ST FTRM1&2 = -.08~+2.3, both oxygen sensor voltages are varying and the LT FTRM1&2 hang around +26 and +28.
From what I understand the ST seems o.k. but the long term is WAY OUT OF WHACK. Started it up again and took carb cleaner spray and covered all the connections I could see = no change in engine rpm. No cracks in the air cleaner body. Big plug to the MAF was inserted and plugging the hole. I am thinking of making a smoke "machine" and trying that or removing the hoses from the throttle body and plugging the holes in the throttle body and see if that clears them up. IF it does then connect one by one and keep checking the values. Lot more work but I am at a loss.
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2002 F150 - 5.4 ... So just bought this truck about a month an a half ago. No problems but the other day the SES came on. It is showing P0171 and P0174. And P0000 (almost forgot that one) was told that's generic though. Haven't really noticed a difference in the way it's running. Has been extremely cold here in WV but the only thing I can notice (or think I notice) is the gas mileage has gone down a little. After reading some on this forum I'm looking for a vacuum leak correct?
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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 have a 99 f150 with the 4.2l v6 with a 5 speed 173000 miles. I picked it up not to long ago. When I first got it it had both the P0171 & P0174 lean on bank 1&2 it was also siting for a while. I replaced the fuel filter which was filled with black fuel, also changed the PCV valve, cleaned the MAF sensor, and changed the oil. I cleared the code, drove it for a little bit and the light came back on after 20 miles.
I then proceeded to replace the upper and lower intake manifold gaskets. Upon doing that i noticed that i was missing one of the linkages for the IMRC. I went to the junkyard and pulled off another linkage rod off the same motor. ordered new plastic clips, put the IMRC on cleaned everything up and began putting it back together. I also cleaned the Injectors while i had them out as well and put in new spark plugs and wires.
Put everything back together. code was cleared since the battery was disconnected. drove it and then the engine light came back on again. this time it was only the p0174. so i then both the upstream and downstream O2 sensors on bank 2, reset the code and it came back on again. I'm lost.
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I have a 1998 F150 5.4L 4WD with 192k mi on it. Recently ( suddenly ) the vehicle began shuttering pretty alerting under light load at 35 - 45mph. The engine idle was intermittently smooth then rough. I quickly drove the truck home and ran a Trouble Code check with my Autoxray EZ-scan 4000 and found the two trouble codes P0302 and P0171. I have checked for vacuum hose cracks and found none.
Replaced the fuel filter, PCV valve, and cleaned the MAF sensor ( dirty ).
Right after cleaning the MAF sensor the idle remained smooth - but stumbling immediately when put in drive. Driving at 35-45mph still exhibits intermittent shuttering and occasional very short bursts of what feel like complete engine shut-down. This all is evident under light to moderate load .
At this point what would you recommend ? Replacing the O2 sensor bank #1 ? Or is there a possibility maybe the EGR valve is faulty - or another vacuum valve somewhere ? Intake manifold leak ?
The severe stumbling and very short complete engine shut downs would indicate that maybe the computer is failing or it's a fuel delivery issue? What rational steps to take next ?
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