P0300 random misfire
06-07-2016, 02:17 AM
#1
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Join Date: Apr 2016
Posts: 24
P0300 random misfire
Well like the title says I have a random misfire code. None of the associated codes identifying specific cylinders it's just the random code.
Symptoms:
It only happens at idle. I get a small shake or tremer from the engine and then the code pops up. I'll clear it via obd-ii scan tool and then after a while it's back again. But it doesn't pop up if the engine is under load (99% sure about that).
I've read on a few different forums that this code is fairly common and the fact that it's only the random code leads others to a conclusion of a possible vacuum leak or Maf failure.
I'd like to know how others successfully solved the problem. I've read bad cat/precat/coils/gas/ and any other emission related parts being replaced. And sometimes to no luck.
I know my fuel is good i only pump she'll 91 into her and I specifically look for pumps that had premium pumped by the last driver(hehehe).
Anyways I'm going to start with plugs and maybe wires since I've never done either, and I have no idea if the previous owner did.
I'm also going to be installing nwp 5pc spacer kit at the same time so that I can clear up any possible intake leaks.
I'm going to be doing new primary 02 sensors since I am getting crappier mileage than I previously did. And now I am getting a P0051 code. (Could that be related to the misfire??)
I also have obx headers sitting in my room but I'm waiting to install those until I get these codes sorted out just in case I am into some money. Unless the headers fix the precat issue that could be causing this? Idk how that could be possible but i would really really love for that to be my solution lol.
Sorry for the rant boys and thanks in advance.
One more thing. All that's changed on the car before the misfire code started was a new k&n pod filter to replace my stock air box with a k&n drop in.... Could it be that somehow disrupted my Maf sensor?
Symptoms:
It only happens at idle. I get a small shake or tremer from the engine and then the code pops up. I'll clear it via obd-ii scan tool and then after a while it's back again. But it doesn't pop up if the engine is under load (99% sure about that).
I've read on a few different forums that this code is fairly common and the fact that it's only the random code leads others to a conclusion of a possible vacuum leak or Maf failure.
I'd like to know how others successfully solved the problem. I've read bad cat/precat/coils/gas/ and any other emission related parts being replaced. And sometimes to no luck.
I know my fuel is good i only pump she'll 91 into her and I specifically look for pumps that had premium pumped by the last driver(hehehe).
Anyways I'm going to start with plugs and maybe wires since I've never done either, and I have no idea if the previous owner did.
I'm also going to be installing nwp 5pc spacer kit at the same time so that I can clear up any possible intake leaks.
I'm going to be doing new primary 02 sensors since I am getting crappier mileage than I previously did. And now I am getting a P0051 code. (Could that be related to the misfire??)
I also have obx headers sitting in my room but I'm waiting to install those until I get these codes sorted out just in case I am into some money. Unless the headers fix the precat issue that could be causing this? Idk how that could be possible but i would really really love for that to be my solution lol.
Sorry for the rant boys and thanks in advance.
One more thing. All that's changed on the car before the misfire code started was a new k&n pod filter to replace my stock air box with a k&n drop in.... Could it be that somehow disrupted my Maf sensor?
Last edited by MuskokaMaxima; 06-07-2016 at 02:19 AM.
06-07-2016, 04:59 AM
#2
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Join Date: Mar 2006
Location: Cumming, GA USA
Posts: 65
Musko - I just posted with the same sort of problem. Tell us more of your maxima - year, model, # of miles.
fwiw - a P0051 is "Heated oxygen sensor (HO2S) 1, bank 2, heater control -circuit low "
cg
fwiw - a P0051 is "Heated oxygen sensor (HO2S) 1, bank 2, heater control -circuit low "
cg
Last edited by cgilley; 06-07-2016 at 05:24 AM.
06-07-2016, 06:11 AM
#3
A vacuum leak can cause the p-0300 code but it usually comes with more noticeable symptoms of a vacuum leak. You should be able to find a vacuum leak that size by spraying brake parts cleaner and listening for the RPM change when it hits the leak.
How old are the plugs? The plugs are often ignored on these cars since they're hard to get to. If you're doing the spacers it's a good time to do the plugs.
The new air filter upgrade could possibly cause MAF problems. Those filters use oil to catch the dirt. The MAF can't handle getting any oil on it. If it was over oiled it could have contaminated the MAF. Get a can of MAF cleaner and spray the MAF. For a couple dollars it's worth a try.
How old are the plugs? The plugs are often ignored on these cars since they're hard to get to. If you're doing the spacers it's a good time to do the plugs.
The new air filter upgrade could possibly cause MAF problems. Those filters use oil to catch the dirt. The MAF can't handle getting any oil on it. If it was over oiled it could have contaminated the MAF. Get a can of MAF cleaner and spray the MAF. For a couple dollars it's worth a try.
06-09-2016, 06:25 AM
#4
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Join Date: Apr 2016
Posts: 24
Well the k&n filter was pre oiled and and not soaked or anything just lightly oiled the way it sboud be. I took a drive over to the Nissan dealer close to my house to have a chat with the service rep. He said best/easiest place to start on the random misfire code would be plugs/intake leak/bad injector(s), low compression, and various short circuits in the system that could be causing it. Also he had mentioned a couple other things that have been suggested on the forums. He was leaning towards the same idea that it is something that would be effecting all cylinders and not just one. He said coils don't usually go 6 at a time.
My car has 225xxxkm it's the 2002 maxima se 6spd.
I guess it's possible that It could be the Maf sensor but I am not about to tamper with it since it's so sensitive and I don't think it's the issue.
Car runs fine and has no loss of power. Just gets a small shake only at idle and not all the time. Any amount of load on the engine and the misfire goes away. Hell even the a/c is enough load to smooth out the idle...
I'm going to start with plugs/ intake leaks/ and compression and a leak down test. I have a feeling that low compression is rarely looked at and it was one of the items that came up on his computer for a fix to my problem.
My car has 225xxxkm it's the 2002 maxima se 6spd.
I guess it's possible that It could be the Maf sensor but I am not about to tamper with it since it's so sensitive and I don't think it's the issue.
Car runs fine and has no loss of power. Just gets a small shake only at idle and not all the time. Any amount of load on the engine and the misfire goes away. Hell even the a/c is enough load to smooth out the idle...
I'm going to start with plugs/ intake leaks/ and compression and a leak down test. I have a feeling that low compression is rarely looked at and it was one of the items that came up on his computer for a fix to my problem.
06-09-2016, 06:47 AM
#5
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Join Date: Sep 2008
Location: Connecticut
Posts: 836
I would guess your car does have loss of power and you only think the misfire goes away under load. This happened to me with the p0300 code a the stutter at idle. One day I pushed the car hard and got the cylinder code. Replaced coil and all is well.
Just a thought
Just a thought
Last edited by 2damax; 06-09-2016 at 07:36 AM.
06-09-2016, 07:07 AM
#6
Plug wires hehe
Yeah, sometimes a slight misfire isn't detected right.
Yeah, sometimes a slight misfire isn't detected right.
06-09-2016, 11:19 AM
#7
The MAF isn't as fragile as it's made out to be. You can pull it and spray it with MAF cleaner with no problem. The original MAF was prone to failure and has since been updated. It's fragile to oil and contaminates but not to handling. It could be that even the properly oiled filter was just too much for the already dirty MAF. It makes sense to do the cheapest easiest tests first.
If you do replace the MAF don't go through the dealer. Hitachi makes a good replacement for much cheaper. It's super easy to install.
If you do replace the MAF don't go through the dealer. Hitachi makes a good replacement for much cheaper. It's super easy to install.
06-09-2016, 02:29 PM
#8
The MAF isn't as fragile as it's made out to be. You can pull it and spray it with MAF cleaner with no problem. The original MAF was prone to failure and has since been updated. It's fragile to oil and contaminates but not to handling. It could be that even the properly oiled filter was just too much for the already dirty MAF. It makes sense to do the cheapest easiest tests first.
If you do replace the MAF don't go through the dealer. Hitachi makes a good replacement for much cheaper. It's super easy to install.
If you do replace the MAF don't go through the dealer. Hitachi makes a good replacement for much cheaper. It's super easy to install.
06-12-2016, 01:51 AM
#9
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Join Date: Apr 2016
Posts: 24
Thanks for the tips guys I will try cleaning the Maf tomorrow I was under the assumption that they could be easily damaged. Idk if I want to take brake clean to it tho seems kinda harsh, but if others have tried it with good results then I'll give it a shot.
I think I have a good feel of how my car performs and I don't notice a loss of power but how much are we talking here? Obviously a minor amount won't be felt but if the car is in some sort of "limp mode" I would think it should be a significant amount to keep the engine from hurting itself. I'm just talking ideas here and have no proof. Other then the fact that my car is still advancing ignition timing to the same point it always has under WOT. I know this via the data graphs I'm able to read on my obd2 scan tool.
unless it goes into a rich airfuel map which I have no idea of other than my usuall fuel economy remaining unchanged.
So I'll try simple things like Maf cleaning (with brake clean???) and plugs and check for any intake manifold leaks to the best of my ability. The only problem with coils is that I have no idea which one to start with. I am not getting any of the individual cylinder misfire. My dad does have a few quality voltage meters kicking around I could test the coils if someone could give me a detailed instruction on how to do it.
It is worth noting the code hasnt returned since maybe Friday morning just to show how inconsistent this code is. Some days I'll clear it multiple times and then others none at all. Same tank of gas.
I think I have a good feel of how my car performs and I don't notice a loss of power but how much are we talking here? Obviously a minor amount won't be felt but if the car is in some sort of "limp mode" I would think it should be a significant amount to keep the engine from hurting itself. I'm just talking ideas here and have no proof. Other then the fact that my car is still advancing ignition timing to the same point it always has under WOT. I know this via the data graphs I'm able to read on my obd2 scan tool.
unless it goes into a rich airfuel map which I have no idea of other than my usuall fuel economy remaining unchanged.
So I'll try simple things like Maf cleaning (with brake clean???) and plugs and check for any intake manifold leaks to the best of my ability. The only problem with coils is that I have no idea which one to start with. I am not getting any of the individual cylinder misfire. My dad does have a few quality voltage meters kicking around I could test the coils if someone could give me a detailed instruction on how to do it.
It is worth noting the code hasnt returned since maybe Friday morning just to show how inconsistent this code is. Some days I'll clear it multiple times and then others none at all. Same tank of gas.
06-12-2016, 06:17 AM
#10
You'd know if it was in limp mode. The car would barely be able to drive or you'd be limited to a very low RPM.
I haven't tried brake parts cleaner on the MAF but I do trust Child_uv_KoRn on the subject. They also make MAF cleaner which is like a kinder gentler brake cleaner. It's under $10 and will last years. It's good to give the MAF a spray every oil change. Especially with aftermarket oiled filters.
The MAF works by heating up a small wire which is cooled by the air flowing past it. It measures how much power is needed to keep the temp. Even a thin layer of dirt and oil will insulate the wire and trick the MAF into thinking less air is flowing.
Can you read the long term fuel trims with your reader? The fuel trims will tell if you're running rich or lean and tell if one bank is different. A lot of info can be gained by watching the fuel trims. There are a lot of you-tube videos explaining fuel trims very well. Overall it's pretty simple.
Testing the coils usually wont give any useful results unless a coil is dead which isn't the case here. If you can narrow the issue to one bank using the fuel trims you can start swapping coils between banks to see if the problem migrates.
How old are the spark plugs?
I haven't tried brake parts cleaner on the MAF but I do trust Child_uv_KoRn on the subject. They also make MAF cleaner which is like a kinder gentler brake cleaner. It's under $10 and will last years. It's good to give the MAF a spray every oil change. Especially with aftermarket oiled filters.
The MAF works by heating up a small wire which is cooled by the air flowing past it. It measures how much power is needed to keep the temp. Even a thin layer of dirt and oil will insulate the wire and trick the MAF into thinking less air is flowing.
Can you read the long term fuel trims with your reader? The fuel trims will tell if you're running rich or lean and tell if one bank is different. A lot of info can be gained by watching the fuel trims. There are a lot of you-tube videos explaining fuel trims very well. Overall it's pretty simple.
Testing the coils usually wont give any useful results unless a coil is dead which isn't the case here. If you can narrow the issue to one bank using the fuel trims you can start swapping coils between banks to see if the problem migrates.
How old are the spark plugs?
06-12-2016, 01:37 PM
#11
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Join Date: Apr 2016
Posts: 24
thanks Derrick i never knew how a Maf sensor worked that is a pretty cool actually. I'm going to try brake clean if you guys say so. And plugs have never been done by me so I couldn't say how old they are.
And yes I can read long term and short term fuel trims via the obd2 tool.
And yes I can read long term and short term fuel trims via the obd2 tool.
06-12-2016, 06:51 PM
#12
That's how our MAFs work. It's called a "hot wire".
There are other types as well.
I'd be looking at the plugs. Pull the front ones and see what they look like but remember that people have been known to swap the front plugs and leave the back ones in place.
Check out the you-tube vids on diagnosing using fuel trims. They'll give a better explanation than I can type up but we can answer questions here. You can diagnose vacuum leaks, fuel issues, and other problems once you start to understand how it works.
This guy has two good vids on fuel trims this one and the part 2.
There are other types as well.
I'd be looking at the plugs. Pull the front ones and see what they look like but remember that people have been known to swap the front plugs and leave the back ones in place.
Check out the you-tube vids on diagnosing using fuel trims. They'll give a better explanation than I can type up but we can answer questions here. You can diagnose vacuum leaks, fuel issues, and other problems once you start to understand how it works.
This guy has two good vids on fuel trims this one and the part 2.
06-14-2016, 02:07 AM
#13
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Join Date: Apr 2016
Posts: 24
That's how our MAFs work. It's called a "hot wire".
There are other types as well.
I'd be looking at the plugs. Pull the front ones and see what they look like but remember that people have been known to swap the front plugs and leave the back ones in place.
Check out the you-tube vids on diagnosing using fuel trims. They'll give a better explanation than I can type up but we can answer questions here. You can diagnose vacuum leaks, fuel issues, and other problems once you start to understand how it works.
This guy has two good vids on fuel trims this one and the part 2.
Secret of Engine Problem Diagnosis- Fuel Trims Pt.1 - YouTube
There are other types as well.
I'd be looking at the plugs. Pull the front ones and see what they look like but remember that people have been known to swap the front plugs and leave the back ones in place.
Check out the you-tube vids on diagnosing using fuel trims. They'll give a better explanation than I can type up but we can answer questions here. You can diagnose vacuum leaks, fuel issues, and other problems once you start to understand how it works.
This guy has two good vids on fuel trims this one and the part 2.
Secret of Engine Problem Diagnosis- Fuel Trims Pt.1 - YouTube
Awesome,Thanks derrick! Been busy helping my parents with their backyard/pool so I haven't gotten around to diagnosing anything yet. But today after work I can start my trouble-shooting.
It's starting to bug me I love this car and she deserves to be well Maintained. Especially for enduring everything I put the poor gal through lol.
I'm also going to pick up my compression tester I lent out. I'll test the front 3 while I check the plugs to see if there is any variance. I know my 800cc snowmobile engine would be getting a new piston and rings if there was a 15psi variance between any of the 3. But how much is acceptable in a "healthy" v6 4stroke?
Compression is something that is dwelling in the back of my mind right now.
Do you think (or anyone who might be lurking this thread) that if one cylinder was down on compression and causing this misfire, that it would not be random? And should be identified as a misfire in a specific cylinder??
Again, thanks for the info Derrick.
06-14-2016, 05:55 AM
#14
You should get a P-030x, with x being the cylinder, if it detects the problem in just one cylinder. I don't know how specific it is though. I think it has to be a strong misfire to give more that the P-0300.
I don't know the exact variances that are acceptable when checking compression. Others here will hopefully chime in.
It's a fair amount of work to pull the rear plugs for a compression check so it would make sense to have some new ones handy. If you find an obvious problem you can always return the plugs.
How long, and for how many miles, have you had the car?
I don't know the exact variances that are acceptable when checking compression. Others here will hopefully chime in.
It's a fair amount of work to pull the rear plugs for a compression check so it would make sense to have some new ones handy. If you find an obvious problem you can always return the plugs.
How long, and for how many miles, have you had the car?
06-16-2016, 11:09 AM
#16
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Join Date: Sep 2014
Posts: 35
It seems to me compression would not be the problem. A low compression misfire should be consistent, not random. At your kms (pretty low mileage - approx 140,000 miles) there shouldn't be enough normal wear to affect compression UNLESS it was regularly beaten and neglected. If so, there would likely be other visible indicators of that. Pretty unlikely that only one cylinder would lose compression without some foreign object being ingested and that would be a sudden development that you would know about. If the previous owner did it, the car would never have worked right for you. I doubt if a load such as turning on the AC would hide a low compression miss.
If you do check the compression, max 10% variance is the number your looking for (or don't really want - lower is better).
As said, clean the MAF. Also, check all the hose connections and plugs around the airbox/MAF area FIRST since that is where you were working.
Cheers,
Glenn
If you do check the compression, max 10% variance is the number your looking for (or don't really want - lower is better).
As said, clean the MAF. Also, check all the hose connections and plugs around the airbox/MAF area FIRST since that is where you were working.
Cheers,
Glenn
06-17-2016, 05:37 AM
#17
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Location: Cumming, GA USA
Posts: 65
Musko - get it fixed? Before I would start tearing things apart, start with your coils. Just unplug each one and listen for a change. You'll know. If you unplug one and nothing happens - there is the problem. See my thread a little before yours.
07-06-2016, 10:37 PM
#18
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Well boys I'm in for some real problems now. Pretty sure the input shaft bearing is gone in my transmission. Currently playing out my options. I'm pretty rattled right now because it was my own stupid fault. I didn't hit second properly And I was clutching really fast so I ended up grinding second haaaard. I feel like such a rookie blowing my tranny on a 1-2 shift.
Loud knocking related to tranny speed that goes away when clutch is disengaged. Very loud in first and progressively quiter as I shift to 6th.
I Got a line on a trans from a wrecker near my house for 350 Canadian I just need to check if it's an hlsd..
Loud knocking related to tranny speed that goes away when clutch is disengaged. Very loud in first and progressively quiter as I shift to 6th.
I Got a line on a trans from a wrecker near my house for 350 Canadian I just need to check if it's an hlsd..
Last edited by MuskokaMaxima; 07-06-2016 at 10:39 PM.
07-06-2016, 10:40 PM
#19
Well boys I'm in for some real problems now. Pretty sure the input shaft bearing is gone in my transmission. Currently playing out my options. I'm pretty rattled right now because it was my own stupid fault. I didn't hit second properly And I was clutching really fast so I ended up grinding second haaaard. I feel like such a rookie blowing my tranny on a 1-2 shift.
Loud knocking related to tranny speed that goes away when clutch is disengaged. Very loud in first and progressively quiter as I shift to 6th.
I Got a line on a trans from a wrecker near my house for 350 Canadian I just need to check if it's an hlsd..
This is what happens when you beat on a car for 30000km.
Loud knocking related to tranny speed that goes away when clutch is disengaged. Very loud in first and progressively quiter as I shift to 6th.
I Got a line on a trans from a wrecker near my house for 350 Canadian I just need to check if it's an hlsd..
This is what happens when you beat on a car for 30000km.
Last edited by Child_uv_KoRn; 07-06-2016 at 10:45 PM.
07-06-2016, 10:49 PM
#20
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Your really getting my hopes up because I initially thought the same thing. But a few others had told me different.
Just to give you some more info the knocking rattling doesnt follow a "rhythm"
When it happened It felt like it was in gear but it just didn't grab. And like an idiot I did it again trying to keep my momentum from the miss shift and again it just revved out.
I limped it home and the clutch pedal didn't feel strange. And from a dead stop it would engage and i would take off like normal, just with lots of noise.
It's loudest under load as well and gets very faint when I give it enough gas to just coast without engine breaking.
Just to give you some more info the knocking rattling doesnt follow a "rhythm"
When it happened It felt like it was in gear but it just didn't grab. And like an idiot I did it again trying to keep my momentum from the miss shift and again it just revved out.
I limped it home and the clutch pedal didn't feel strange. And from a dead stop it would engage and i would take off like normal, just with lots of noise.
It's loudest under load as well and gets very faint when I give it enough gas to just coast without engine breaking.
07-06-2016, 10:58 PM
#22
Only one way to find out
Considering how easy it is to drop the tranny, get to it 
07-06-2016, 11:41 PM
#23
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yeah it sounds like marbles. . Bearing is shot isn't it.
Clutch is getting done regardless now because it's obviously one or the other and that clutch won't chirp 3rd anymore (and that's just unacceptable).
About how many hours labour for a pro to re and re a transmission?
I have a friend who's rate is too cheap not to let him do the work. So it will be going to him.
Clutch is getting done regardless now because it's obviously one or the other and that clutch won't chirp 3rd anymore (and that's just unacceptable).
About how many hours labour for a pro to re and re a transmission?
I have a friend who's rate is too cheap not to let him do the work. So it will be going to him.
Last edited by MuskokaMaxima; 07-06-2016 at 11:50 PM.
07-06-2016, 11:59 PM
#24
yeah it sounds like marbles. . Bearing is shot isn't it.
Clutch is getting done regardless now because it's obviously one or the other and that clutch won't chirp 3rd anymore (and that's just unacceptable).
About how many hours labour for a pro to re and re a transmission?
I have a friend who's rate is too cheap not to let him do the work. So it will be going to him.
Clutch is getting done regardless now because it's obviously one or the other and that clutch won't chirp 3rd anymore (and that's just unacceptable).
About how many hours labour for a pro to re and re a transmission?
I have a friend who's rate is too cheap not to let him do the work. So it will be going to him.
That sucks.Haven't done it without the motor, too, but a few hours. Book time is high at 5.5.
If he knows how, he could just fix it depending on cost. Make sure to get some redline or amsoil gl4 fluid.
07-07-2016, 12:08 AM
#25
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He's not into fixing the transmission. Of the 2 very experienced shops i use. Neither want the headaches involved with fixing transmissions and I get that.. And redline has been in that tranny since the day I got it
I guess now I own two money pitts
One is a 2002 maxima se . And the other is a 2002 mach z tech plus.
I guess now I own two money pitts
One is a 2002 maxima se . And the other is a 2002 mach z tech plus.
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