I took my 2006 W12 to get its yearly smog check, and it will not run "air" monitors due to intermittent misfire. The code is P0300.
Any way clearing this up? (I could find no air leaks)....
I've got the intermittent misfire codes on my '02 Camry, and after changing the spark plugs and the ignition coils the problem still persists.
At first there was no noticeable misfire, I took it to two different mechanics and neither said they could find anything wrong. A few weeks later the misfire became noticeable when I'm sitting at a stop light. I can feel an occasional rumble in the engine.
I have a 2007 Hyundai Accent GLS. I just got it from a used car dealership (local) and it runs perfectly. It had a misfire code when i first got it, for all cylinders plus the p0300. It went away when i started the engine again, and didnt come back til a month later (Now). now it wont go away.
I went to advance auto and had them use their OBD2 reader for a trouble code and i got p0300, p0301, p0303, p0304. No other codes present.
I am not feeling anything bad, and from what I am told, a misfire feels like a hard shift. This is of course after getting the plugs and wires changes as well as an oil change. Standard preventative maintenance.
The mechanic used OEM parts got from local parts shop. i think the OEM plugs are the copper ones. I would have preferred iridium as they arent that much more expensive but I don't want to pay for another plug change.
The only symptoms I can think of, is that according to google, I should get around 380 miles to a full tank (11.9 capacity, 32 mpg city). I am only getting 280 from full tank to gas light.
I have also gone through a lot of oil. I checked the dipstick and it was below the low line, so i bought a quart of high mileage oil (same exact brand and type of oil that i gave to the mechanic to use) and it went to just above the full line. This was at around 1500 miles after oil change.
After visiting multiple sites about misfires, i found a few things that caught my attention. One is a site called auto service professional, which talks about the OCV for the MC accent. A lot of sites also recommend gaping the plugs at .035.
I know it is a random cylinder misfire code however I started my car in the morning and it was fine I moved it and put it back in my driveway. I started it up later and waited for it to heat up i came back outside 10 min later and my check engine light was flashing and my car was shaking like crazy you could tell the engine was misfiring like crazy. I had under a quarter of a tank but not empty yet. I shut it off and turned it back on and it was still doing it. I drove the mile to the gas station the way it was.
Under partial throttle it was revving to 4500 and over 5, had to let of throttle to make the car shift up a gear. I filled up and started the car again performed fine after that however the check engine light was solid now and still on. I went to my local mechanic and he read that code P0300. I changed my spark plugs that day and they were crap the original spark plugs I have 65,xxx on my car now. Car is smooth now. I cleared check engine when i saw him first and it did not come back on all day even before i changed the spark plugs later that night. Why my light was flashing and why my car was acting like that till i filled up?
'02 TB w/ code P0300 / Random misfire. Started the other day when it was very damp out, FWIW. Feels like ur driving on rumble strips during acceleration. Rough idle also. It does not do this continually though as after a while (minute) it clears up and runs smooth for a while then runs rough & light will again for a while. I seafoamed it today since it been about 60k since last seafoam. I thought that might have worked until I drove about 20 mile and it went rough again. I also cleaned the oil out of the cam sensor elect connector, since that caused rough running before, although it didn't throw that code. It seems to be very intermittent. '02 TB, 185k miles, orig plugs changed at 125k. Is it actually just going in & out of a limp-mode? O2 since it's random ???
View 14 RepliesI have a 2000 Suburban 4wd that has a p0300 code. The misfires are coming mainly from #2 and #7 cylinders. Misfires only occur at idle. over 1500 rpm the misfires disappear. I have put new A/C Iridium plugs in, new wires, and new coil packs on both cylinders but the problem is not any better. All 8 fuel injectors all go to 55 psi when activated and drop to 28 when released. All tests were done with my Snap-On Solus.
View 2 RepliesRecently i started the car and it was shaking more that usual. the CEL light came stating P0300 with random misfires. It sounds and feels like misfires so i believe this is true.
View 10 Replies2004 GMC Sierra 2500 HD, 227,000 miles 6.0L V8.
While driving up hills or increasing load, the CEL will flash multiple times, I pull over as I know CEL flashing is not good. I turn the truck off, allow it to sit for a few minutes, whip out the code scanner, only code that was there happens to be P0300. Truck has poor MPGS, idles rough, loss of power. this happens every time I drive this vehicle as I use this truck to pull my trailer that weighs around 4000 lbs. Problems come and go. Some days I can drive the truck for an hour with no problems, come up to a red-light, BAM, CEL is flashing, truck is bouncing side to side due to the poor idle, other days this happens while sitting in the parking lot of my job with the ac on.
Truck has been to the shop several times as I'm no mechanic. Parts replaced are as follows:
- Fuel pump
- Throttle Body
- All plugs
- All wires-All Coils
- Intake Manifold Gasket-
- Battery
- Sensor 1 Bank 1 O2 Sensor
- Sensor 1 Bank 2 O2 sensor
I have a 2004 Hyundai Santa Fe 3.5L V6 when i was driving a couple of days ago the check engine light flashed and after a while it stayed on the codes are P0300 which is a random misfire as well as a misfire in cylinder 2, 4 and 6
I replaced all 6 spark plugs and the 3 spark plug wires still the same issue. The car hesitates when accelerating when i accelerate it looks like it wants to stop the rpm goes to almost zero and then it moves and so on. the rpm goes up and down like crazy.
Sometimes it won't move past 1000 rpm I'm moving 60mph and still on 1000rpm and sometimes it works just fine like there is no issue at all. When idle the car is fine and everything seems normal it stays on 900rpm. The car has 158K miles on it.
I uploaded a video to show you what's happening to the tachometer when I accelerate [URL] ....
I'm on a limited budget I'm thinking of changing the ignition coils but i want to make sure that's what is causing the problem first because i spent 200$ to change spark plugs and wires and the mechanic didn't fix the issue.
2005 4cyl. Vue with 54K... Steady CEL. Runs great. Absolutely no problem accelerating. Don?t hear or feel any misfiring. There is a slight rumbling sound when I first start to drive the car, but to me, the sound doesn't seem come from the engine, but rather underneath the car. It goes away when I continue to drive. Since winter began, I occasionally feel a very slight hesitation during idle?happened once or twice lately.
Again, I only feel justified in mentioning it simply because of the codes that were generated. None of my passengers have made a comment about the idle or the drive. My friend, however, made a remark that occasionally, there is a very very very slight hesitation at the downshift when braking. No crack in gas cap. Great fuel economy. No problems accelerating at all. Never hear or an actual misfire, which I take it, means a problem when accelerating, a jerking, or popping noise.
Took it to a dealer. Codes were 0300, 301, 302, 303, 304?302 generating most often. Dealer recommended new ignition module and plug replacement, but they said it wouldn?t be a guaranteed fix and that it may need EGR replacement (don?t hear knocking though) or be a burnt valve in the cylinder. No suction out tailpipe, no rotten egg smell (signs of burnt valve). What are the chances of burnt valve in a car with 54K anyway?
Also, my maintenance schedule claims that I don?t need new spark plugs until 100K. Is there anything else this could be such as a dirty injector system, fuel filter, fuel pump, or air filter? Again, overall, the car runs GREAT! Should I just wait and see if the misfire becomes more pronounced so when I take it to a mechanic, they won't be looking for a needle in a haystack?
Ok I am at my wits end with this. I have a 2000 Mustang GT 5-speed with 80k miles. When the A/C is on it will occasionally misfire at steady, low (between 1-2k) RPMs and will have a fluctuating idle as well. Occasionally the fluctuating idle is bad enough that it stalls out. It only does this when the compressor is engaged. It sounds like a vacuum leak, but I have checked and cannot find any sort of vacuum leak. Also, it throws a P0300 (Random/Multiple misfire) code. When the A/C is off it runs like a charm. Here is everything that I have done...
Replaced COPs
Replaced spark plugs
Cleaned MAF sensor
Cleaned IAC valve
Replaced fuel filter
Replaced fuel pump (unrelated to this, the old one just died)
Ran seafoam through the motor
New battery (again, unrelated)
and maybe some other stuff I am forgetting
Also, I have taken some readings:
Fuel pressure @ idle ~32psi
Vacuum @ idle ~17in Hg
Had alternator tested - OK
Pressure in A/C system checked out OK (though I did use one of those AZ cans with a gauge on it, not sure how reliable that is)
Also, the A/C works great. It's like an arctic wind in there.
I am at a total loss for what to do. I would suspect it's something with the motor that is simply exacerbated by the added load of the A/C but I suppose it could be the A/C compressor? Is it possible that it needs lube? Doesn't the freon lube the compressor? (The pressure indicates it's fully charged and the A/C blows cold AF) ...
I have a p0300 code coming up on the comp. The motor runs fine until it gets wet. rain/carwash. I have tried to spray each coil with water and could not get it to misfire. Then I brought out the water hose and sprayed it top of the motor this found the misfire. This thing has 8 coils and I really don't want to replace them all. My Question is there some thing else that could be causing the misfires.
View 14 RepliesI have a 2000 Impala with a 3800 V6 series 2 with 165,000 miles. The only code I had was a P0300 Multiple random misfire that occured off and on at first, Worse in the city Better on Highway. It would start running on half the cylinders and bogged down, with the check engine light flashing, after getting onto the highway it would straighten itself out at first. I thought i had water in the gas so i ran some heat through it. straightened out for a day then happened again so I thought maybe a should run some premium gas in it, The car ran like total crap until the premium was gone, so i thought maybe it's running too rich, I put 87octane in it and it ran great for a day or two, then it gradually got worse to where it would not straighten up on the highway, tried to die at stoplights and i had to drive it with 2 feet to get it home and park it. I've replaced the battery, spark plugs, wires, ICM checked good, coil packs are good, replaced fuel Pressure regulator, looked for arcing on the spark plug heat shields and it will not start. It turns over but doesn't try to ignite and when I get the slightest rumble of ignition, it backfires up through the manifold and I see a puff of gas or light smoke by the exhaust manifold.
The car had a vacuum leak around the intake manifold cover gasket and a leak on the fuel rail. I pulled the fuel rail off my impala, snugged up the rest of the intake bolts then disassembled the fuel rail, flushed it out and cleaned the injectors the best i could, then reassembled it. before i re-installed the fuel rail I hooked it up to the fuel lines outside of the engine and tried to start the vehicle. all injectors had a nice spray pattern. So i installed the rail and it still didn't start but it had more combustion than before although it's still backfiring like before. Checked the fuel pressure by turning the key on and the fuel pressure went to zero very fast. I blew the rail out with air so to make sure i didn't damage the regulator I replaced it with the old one, ran the test again with same results, so i reinstalled the new regulator. I performed the fuel pressure test a few more times while moving the fuel hoses and when i moved the back supply line the vacuum loss stopped then dropped to zero when i let off of it. So I replaced the fuel line connector and O-rings on the injectors. It no longer has a vacuum leak.
I cleaned the EGR Valve out and had no luck there, then I removed the Idle Air Control Valve-pushed the pintle in, re-ionstalled it and WooHoo! it started! Although it still ran like crap with the same random misfire I was still happy to hear it start.I pulled the plugs on it to do a compression test and all 6 cylinders have between 180-190psi so the engine is in good condition mechanically. I installed new plugs before getting the car restarted and when i removed them for the test they were covered in thick black soot after running for roughly 15 minutes max.
I have (2) 2000 Chevy Impala's so I've swapped sensors from my wifes car to see if it would fix it. I've tested the following MAP, MAF, IAC, coil packs and ECM. None of these made the car change. I believe it is a timing chain because the car has never had a new timing chain and is way overdue, but I haven't had a code for a crankshaft position sensor. Can the timing chain be bad without throwing a code? It's not out of time enough to change the valve timing because I had a good compression test but its not firing right and still has the multiple random misfire. I have not checked or received a trouble code for o2 sensors, crankshaft position sensor or cam sensor. Something has the timing retarded and is dumping extra fuel into the engine because my new plugs looked like they were in the engine for a year.
My 03 Chev Avalanche is giving me a P0300 code (multiple or random misfire). With no distributor or individual coil is this something I can fix myself or is it shop time?
View 6 RepliesHad this code show up after the warning light came on and then the light went away after two day, the car seems to be a little sluggish now. I have read that this is a random engine misfire and it could be a bad plug..
View 1 RepliesJust started getting a p0300 random misfire code on the durango a couple days ago. pretty sure it isn't moisture related since it started on a nice sunny day. it was running pretty rough so it was obvious that it was misfiring. I changed the plugs since it was about time anyway, and they needed it and I cleared the codes. new plugs (put in the oem champion copper plugs) didn't make the problem go away. The engine still ran rough and the code came back. 2 of the plugs looked like they may have been fouling a little bit. they were a fair bit blacker than the rest of the plugs. I went ahead and changed the coils on those two cylinders and reset the codes again. Still runs rough and the p0300 came back. where do I go from here? I am not getting any specific cylinder codes so it makes sense to me that it isn't one or two cylinders not getting spark. 2003 durango 4.7 ....
View 6 RepliesNew plug on right, lower bank 2 plug on left
Started getting a P0300 and various misfire codes for random cylinders. Truck has 95,000 kilometers so figured I would change the plugs. Several of the plugs on the lower bank on both sides were pretty much toast. Most of the plugs on the top looked good. All of the plugs had a small deposit where the spark hits the ground probe. Picture is typical plug from lower side. changing the plugs should make a big difference in how she runs and eliminate the codes.
Took right on 4 hours same as dealer said it would. I would have got it quicker but it was not a race.
I am trying to get a 2009 Sonata NF with a 3.3L V6 to run correctly and i have tried everything that i can find and still get the problem. The car runs very rich with a strong gas smell. The engine runs rough but doesn't stall. The car has has period where it runs fine and then the issue returns but is in more frequent and steady now. The car will run for the first 5 minutes great if it is cold and it also runs good at full throttle and the check engine light went off during hard acceleration which seems consistent with getting too much fuel. I bought a BlueDriver to read the codes and I love the data it provides but I am learning all the features.
For a little history the car has 95,250 miles. At 81157 miles the check engine light came on and an independent shop replaced the downstream O2 sensor and the light has been off for 2 years until coming back on recently. The code showing was a P0300. The shop replaced spark plugs and the manifold gasket with and oil change for $775. The check engine light stayed off for about a month and 550 miles. The car was taken back to the shop and they replaced the rear O2 sensor for $429 . The check engine light was off for a couple of days and then returned with the P0300. It might go a couple of days without a problem and then it would return.
This is when I got the car and started reading all the forums i could for possible causes. I saw the Tech Bulletin on the Variable Valve Timing Oil Control Solenoids so i replaced both valves. The check engine light returned with a P0303 for cylinder 3 misfire so i figured it was a coil so i replaced all the coils. The P0300 code returned. I check fuel pressure after seeing a post about fuel pressure regulators causing the problem but the pressure was correct. I changed the Mass Flow Sensor figuring it was getting too much gas but no improvement. I bought the BlueDriver so I could see more than just the codes. The O2 sensor looked erratic so i changed the front upper O2 sensor.
I found the Tech Bulletin about the O2 sensors fuel trim readings and realized there was an upper sensor on the back manifold and it was reading -18% so i changed it and now I don't know which way to go. I currently have the P0303 code confirmed and P0300 pending. With the live data the items that looked strange at idle were O2 Sensor Bank 1 Sensor 2 steady at 99.2% and Calculated Engine Load a 21.6%. The freeze frame data from when the light came on has all the short fuel trim at 0.0% and long term at -0.8% for both banks. Calculated Engine Load was 45.9% even though I was trying to drive slowly at 29 mph. Mass Air was 21.71 g/s, I had been running 3 minutes from a slightly warm start, Absolute engine load was 44.3%. Anything else to check or data I should look at?
Had the CEL come on twice in the last few days. The first time, a restart of the car took it away. The second time, it came on and stayed over multiple start ups.
With Torque Pro and a bluetooth OBDII dongle I read: P0300 - Powertrain, Random/Multiple Cylinder Misfire Detected
From the Internet:
Possible causes
- Faulty spark plug (s)
- Faulty ignition coil (s)
- Clogged or faulty fuel injector (s)
- Intake air leak
- Fuel injectors harness is open or shorted
- Fuel Injectors circuit poor electrical connection
- Ignition coils harness is open or shorted
- Ignition coils circuit poor electrical connection
- Insufficient cylinders compression
- Incorrect fuel pressure
I wish it wasn't so broad... But, as the car is about to hit 60,000 miles, I plan to replace the spark plugs (NGK), engine air filter, cabin air filter. Just had the timing belt done last week. I will check all of the intake couplings for tightness.
For others who use Torque, what other settings could be useful in pinning down this issue for me? I cleared the CEL this morning; it didn't come back yet.
I posted this problem several months ago about a p301 code that my 2007 Prius has been generating. I eliminated all the easy stuff... plug, spark unit, fuel injector. Over the past year since I've had the car, the CEL light has gone on for a couple months then shut itself off for a couple, then back on ... probably has shut itself off 3 times in the past year, each time staying off about a month or two before coming back on. Some background on the car, supposedly the PO hit a rock and damaged the motor about 2 years ago and had the short block replaced.
Anyway, the CEL has been on again for about a month, and I got a notice for Illinois emission testing, so I decided to take it in to the dealer and have him do a diagnostic so I can get the emissions passed. After an hour and a half of testing they told me that the best they could ascertain, the car has been submerged in water, as there is a lot of rust in areas that never get any rust, and they think there's a short somewhere.
The service manager at the dealership said if it was his car he wouldn't spend the money for another 5 hours of trouble shooting, and if the car runs good he'd just drive it as is. They cleared the CEL and the service manager just charged me for an oil change as they caught a recall on the steering that hadn't been done and figured he'd let me slide on the hundred for the diagnostic.
I have a new (to me) '97 Windstar with 128K +. C.E.L. is on and intermittently flashing. The code reads P0302 (Cylinder 2 Mis-fire). No other codes are set. Have cleared them many times and gone through multiple drive cycles.
Description of issue: After clearing the codes, and indeed upon each startup, the car starts and idles smoothly without hesitation or issue. It pulls away from parked position without issue. Appears to accelerate just fine. In stop-and-go traffic or directly onto the highway it seems to run smoothly without problem. After a period of time (I don't believe it to be consistent), it will start to misfire and the C.E.L. will be set. If it is still misfiring, the light will flash.
Here's the weird part...when stopping at a traffic light or just continuing to drive on the highway, the misfire will resolve and the car will run smoothly again. The C.E.L., trailing the condition by a bit, will go to solid from flashing and will remain that way until a little farther down the road. The misfire never seems to be more than one cylinder and the trouble code seems to bear that out. Just idling, the car will return to smooth operation and it seems to have smooth acceleration. In other words, the misfire seems to go away under acceleration.
What I've done: I've replaced plugs and wires. No change. Replaced Coil pack. No change.
Next steps: Next steps seem to be looking to fuel or air. My concern with that approach is the occasional nature of the problem. Compression problems would be consistent across the board, right? That cylinder would always be a problem. Same thing for fuel (fuel pump and/or filter). All cylinders would have the problem and it would have issues starting. OK, next thing--injector. Would an injector have spotty performance like this? Also, could it be related to the EGR ports on the intake on this vintage Windstar? (Once again, is an intermittent problem consistent?) Finally, since the primary circuit for spark is controlled by a PCM pin setting a ground for each cylinder, could the PCM, or wiring, be the culprit?