P0300 Random Misfire - not coils
11-30-2007, 02:34 PM
#1
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P0300 Random Misfire - not coils
P0300 - Random Misfire - not bad coils
My car has been running pretty bad lately and getting low 21 MPG highway
Has been getting this code a lot, it would come and go, then finally today got P0302 cylinder two misfire, so i swapped the coils with cylinder four but misfire stayed in cylinder number two.
so i took the spark plug out and it looked pretty bad, with a lot of deposits on it.
I changed the plugs a little over 20K miles ago to Denso Iridium...
So i took plugs out of cylinder 4 and 6 and they are all covered in deposits, they must have misfired quite often and were causing my P0300 code.
Anyway, here's the interesting part the Bank 1 plugs (cylinder 1 3 5) looked normal, just the bank 2 ones were messed up (cylinders 2 4 6). Also when looking at the long and short fuel trim through obd-2 the bank 1 was normal but the bank 2 long fuel trim is -11 and short fuel trim is around -10 trying to compensate for rich condition.
on 3.5L to get to bank 1 spark plugs one need to take the intake manifold off, so once taken off i looked inside and it was so weird the runners for cylinders 1, 3, and 5, are clean and dry, but runners for 2, 4, and 6, are covered with oil (they are the lower ones on the intake)...
so that explains the deposits on spark plugs, fouling them, leading to misfire, causing the O2 sensors to see rich running condition, and probably clogging my pre-cat on bank 2.
Now the question is why do i have oil in my intake manifold?
the car now eats 1 quart of oil for every 1K miles, if it burns it all why there's no blue smoke out of exhaust? (are the cats that efficient?)
I checked vacuum at idle and it's steady at 19 inches mercury.
I need to do a compression check...
But if it was bad piston rings then the oil would just burn up inside the cylinders, how does it end up in my intake? PCV valve was replaced a little over 20K miles.
Obviously oil is being sucked in by the intake vacuum, and because the VIAS (power valve) normally separates upper and lower intake runners the oil ends up in the lower runners going into cylinder 2, 4, and 6.
What do i need to fix to stop oil getting inside the intake manifold.
Oil catch can would probably help but it seems like a band-aid rather than solution.
As far as I understand -
1. Clogged pre-cats would not allow for good vacuum at idle.
2. Bad piston rings would not explain oil getting into intake. (or would they?)
3. There is no EGR, so it's not the exhaust gunking up the intake
What would bad valve guide seals do?
Does anyone have any ideas what causing the problem?
Thank you in advance for all your help.
My car has been running pretty bad lately and getting low 21 MPG highway
Has been getting this code a lot, it would come and go, then finally today got P0302 cylinder two misfire, so i swapped the coils with cylinder four but misfire stayed in cylinder number two.
so i took the spark plug out and it looked pretty bad, with a lot of deposits on it.
I changed the plugs a little over 20K miles ago to Denso Iridium...
So i took plugs out of cylinder 4 and 6 and they are all covered in deposits, they must have misfired quite often and were causing my P0300 code.
Anyway, here's the interesting part the Bank 1 plugs (cylinder 1 3 5) looked normal, just the bank 2 ones were messed up (cylinders 2 4 6). Also when looking at the long and short fuel trim through obd-2 the bank 1 was normal but the bank 2 long fuel trim is -11 and short fuel trim is around -10 trying to compensate for rich condition.
on 3.5L to get to bank 1 spark plugs one need to take the intake manifold off, so once taken off i looked inside and it was so weird the runners for cylinders 1, 3, and 5, are clean and dry, but runners for 2, 4, and 6, are covered with oil (they are the lower ones on the intake)...
so that explains the deposits on spark plugs, fouling them, leading to misfire, causing the O2 sensors to see rich running condition, and probably clogging my pre-cat on bank 2.
Now the question is why do i have oil in my intake manifold?
the car now eats 1 quart of oil for every 1K miles, if it burns it all why there's no blue smoke out of exhaust? (are the cats that efficient?)
I checked vacuum at idle and it's steady at 19 inches mercury.
I need to do a compression check...
But if it was bad piston rings then the oil would just burn up inside the cylinders, how does it end up in my intake? PCV valve was replaced a little over 20K miles.
Obviously oil is being sucked in by the intake vacuum, and because the VIAS (power valve) normally separates upper and lower intake runners the oil ends up in the lower runners going into cylinder 2, 4, and 6.
What do i need to fix to stop oil getting inside the intake manifold.
Oil catch can would probably help but it seems like a band-aid rather than solution.
As far as I understand -
1. Clogged pre-cats would not allow for good vacuum at idle.
2. Bad piston rings would not explain oil getting into intake. (or would they?)
3. There is no EGR, so it's not the exhaust gunking up the intake
What would bad valve guide seals do?
Does anyone have any ideas what causing the problem?
Thank you in advance for all your help.
11-30-2007, 02:41 PM
#2
P0300 - Random Misfire - not bad coils
My car has been running pretty bad lately and getting low 21 MPG highway
Has been getting this code a lot, it would come and go, then finally today got P0302 cylinder two misfire, so i swapped the coils with cylinder four but misfire stayed in cylinder number two.
so i took the spark plug out and it looked pretty bad, with a lot of deposits on it.
I changed the plugs a little over 20K miles ago to Denso Iridium...
So i took plugs out of cylinder 4 and 6 and they are all covered in deposits, they must have misfired quite often and were causing my P0300 code.
Anyway, here's the interesting part the Bank 1 plugs (cylinder 1 3 5) looked normal, just the bank 2 ones were messed up (cylinders 2 4 6). Also when looking at the long and short fuel trim through obd-2 the bank 1 was normal but the bank 2 long fuel trim is -11 and short fuel trim is around -10 trying to compensate for rich condition.
on 3.5L to get to bank 1 spark plugs one need to take the intake manifold off, so once taken off i looked inside and it was so weird the runners for cylinders 1, 3, and 5, are clean and dry, but runners for 2, 4, and 6, are covered with oil (they are the lower ones on the intake)...
so that explains the deposits on spark plugs, fouling them, leading to misfire, causing the O2 sensors to see rich running condition, and probably clogging my pre-cat on bank 2.
Now the question is why do i have oil in my intake manifold?
the car now eats 1 quart of oil for every 1K miles, if it burns it all why there's no blue smoke out of exhaust? (are the cats that efficient?)
I checked vacuum at idle and it's steady at 19 inches mercury.
I need to do a compression check...
But if it was bad piston rings then the oil would just burn up inside the cylinders, how does it end up in my intake? PCV valve was replaced a little over 20K miles.
Obviously oil is being sucked in by the intake vacuum, and because the VIAS (power valve) normally separates upper and lower intake runners the oil ends up in the lower runners going into cylinder 2, 4, and 6.
What do i need to fix to stop oil getting inside the intake manifold.
Oil catch can would probably help but it seems like a band-aid rather than solution.
As far as I understand -
1. Clogged pre-cats would not allow for good vacuum at idle.
2. Bad piston rings would not explain oil getting into intake. (or would they?)
3. There is no EGR, so it's not the exhaust gunking up the intake
What would bad valve guide seals do?
Does anyone have any ideas what causing the problem?
Thank you in advance for all your help.
My car has been running pretty bad lately and getting low 21 MPG highway
Has been getting this code a lot, it would come and go, then finally today got P0302 cylinder two misfire, so i swapped the coils with cylinder four but misfire stayed in cylinder number two.
so i took the spark plug out and it looked pretty bad, with a lot of deposits on it.
I changed the plugs a little over 20K miles ago to Denso Iridium...
So i took plugs out of cylinder 4 and 6 and they are all covered in deposits, they must have misfired quite often and were causing my P0300 code.
Anyway, here's the interesting part the Bank 1 plugs (cylinder 1 3 5) looked normal, just the bank 2 ones were messed up (cylinders 2 4 6). Also when looking at the long and short fuel trim through obd-2 the bank 1 was normal but the bank 2 long fuel trim is -11 and short fuel trim is around -10 trying to compensate for rich condition.
on 3.5L to get to bank 1 spark plugs one need to take the intake manifold off, so once taken off i looked inside and it was so weird the runners for cylinders 1, 3, and 5, are clean and dry, but runners for 2, 4, and 6, are covered with oil (they are the lower ones on the intake)...
so that explains the deposits on spark plugs, fouling them, leading to misfire, causing the O2 sensors to see rich running condition, and probably clogging my pre-cat on bank 2.
Now the question is why do i have oil in my intake manifold?
the car now eats 1 quart of oil for every 1K miles, if it burns it all why there's no blue smoke out of exhaust? (are the cats that efficient?)
I checked vacuum at idle and it's steady at 19 inches mercury.
I need to do a compression check...
But if it was bad piston rings then the oil would just burn up inside the cylinders, how does it end up in my intake? PCV valve was replaced a little over 20K miles.
Obviously oil is being sucked in by the intake vacuum, and because the VIAS (power valve) normally separates upper and lower intake runners the oil ends up in the lower runners going into cylinder 2, 4, and 6.
What do i need to fix to stop oil getting inside the intake manifold.
Oil catch can would probably help but it seems like a band-aid rather than solution.
As far as I understand -
1. Clogged pre-cats would not allow for good vacuum at idle.
2. Bad piston rings would not explain oil getting into intake. (or would they?)
3. There is no EGR, so it's not the exhaust gunking up the intake
What would bad valve guide seals do?
Does anyone have any ideas what causing the problem?
Thank you in advance for all your help.
Originally Posted by abakalen
2. Bad piston rings would not explain oil getting into intake. (or would they?)
Do a CT and see how those cyls. In question perform.
11-30-2007, 03:30 PM
#3
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NmexMAX,
That would seem very unlikely for three cylinders to be bad on bank two unless i have a blown head gasket, but then all kinds of bad things would start to happen - antifreeze in oil, antifreeze inside cylinders, pressure build up in cooling system...and etc.
I will do the Compression Test tomorrow, i don't have the tester available to do it today.
I am also looking for leak down tester...any suggestions on where to buy one from?
I was just gonna buy the fittings at Home Depot and make one up myself but they are not that cheap...
Thanks.
That would seem very unlikely for three cylinders to be bad on bank two unless i have a blown head gasket, but then all kinds of bad things would start to happen - antifreeze in oil, antifreeze inside cylinders, pressure build up in cooling system...and etc.
I will do the Compression Test tomorrow, i don't have the tester available to do it today.
I am also looking for leak down tester...any suggestions on where to buy one from?
I was just gonna buy the fittings at Home Depot and make one up myself but they are not that cheap...
Thanks.
12-02-2007, 02:34 PM
#4
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Posts: n/a
i was having a similar problem with my vq35. here is my advice. replace both valve covers with the ones that come on the 6th gen. daveb sellls them cheap. next get some ngk spark plugs either copper or platinum. Now the misfire could be because of the coils or the maf sensor. when i was getting the multiple misfire code , i replaced all 6 coils but it still existed. so i knew it wasnt the coils, so i swapped to a 2k1 maf and the code went away. also remember to do the accelerator pedal relearn and the idle relearn.
03-29-2008, 06:00 PM
#5
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Compression test results
NmexMAX,
That would seem very unlikely for three cylinders to be bad on bank two unless i have a blown head gasket, but then all kinds of bad things would start to happen - antifreeze in oil, antifreeze inside cylinders, pressure build up in cooling system...and etc.
Thanks.
That would seem very unlikely for three cylinders to be bad on bank two unless i have a blown head gasket, but then all kinds of bad things would start to happen - antifreeze in oil, antifreeze inside cylinders, pressure build up in cooling system...and etc.
Thanks.
The rear bank cylinders (1, 3, and 5) are fine around 190 psi plus minus few psis, however it different story for the front bank -
cylinders 2 and 4 are only 100 psi, and cylinder 6 is 175 psi.
That would point out that i have a blown head gasket on front bank.
I do have random misfire P0300 code which is not the coils.
So the big question is do i look for another engine at the junk yard or try to replace the head gasket? the engine has almost 130K miles.
What would you do?
Thanks for any advise.
03-29-2008, 06:58 PM
#7
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SoonerFan,
Is there a way to determine if it's bad rings or blown gasket or possibly valves?
It's just i was always under impression that if the two cylinders next to each other have lower compression that the head gasket is blown.
But i have no oil in my antifreeze and no antifreeze in my oil.
Assuming it's the rings,
can you perform the ring replacement without removing the head by pulling the pistons out from below by simply removing the rod bearing caps?
Is there a way to determine if it's bad rings or blown gasket or possibly valves?
It's just i was always under impression that if the two cylinders next to each other have lower compression that the head gasket is blown.
But i have no oil in my antifreeze and no antifreeze in my oil.
Assuming it's the rings,
can you perform the ring replacement without removing the head by pulling the pistons out from below by simply removing the rod bearing caps?
03-29-2008, 10:01 PM
#9
I agree with Sooner. My car is one of the oil burning blue smoke blowing beasts and cylinders 1 and 3 are running at 130-140 compression and all others are above 180.
Fortunately I now have a 60k engine sitting in my garage waiting for the day I get sick of topping off my oil every 500 miles.
Fortunately I now have a 60k engine sitting in my garage waiting for the day I get sick of topping off my oil every 500 miles.
03-29-2008, 11:04 PM
#10
Replace valve cover. Common problem for the Altima VQ35. The valve cover spark plug tube gaskets fail and allow oil to leak into the tube. Easy fix. Order 04+ Maxima valve covers. Cheaper then 02-03 (02-04 for the Altima) but have beefier gaskets.
03-29-2008, 11:14 PM
#11
I'm pretty sure it's your head gasket. Have you overheated your engine @ all? Jeg's & summit sell leak down testers or you may wanna check at your local aircraft supply center they will definitely have some! Do you know any A&P aircraft techs?
I've been running with Nissan for a long time and I'll bet you it's either your valve seals or head gasket! I'll put most of the money against those valve seals cause the cylinder is puddling up with oil and you probably are getting a good blue cloud in the morning but nothing is visible any other time during operation!
I've been running with Nissan for a long time and I'll bet you it's either your valve seals or head gasket! I'll put most of the money against those valve seals cause the cylinder is puddling up with oil and you probably are getting a good blue cloud in the morning but nothing is visible any other time during operation!
03-29-2008, 11:20 PM
#12
Also one more thing if it were the valve covers your porcelian would be all discolored (brownish) from being submerged in oil. Look @ your coil over plug assemblies are the tips oil soaked? I doubt it!
03-30-2008, 07:25 AM
#13
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Don't have blue smoke while driving but at the start up there is a puff.
i'm gonna get a leak down tester and see what the results would be...
still the valve guide seals wouldn't explain low compression...
thanks you all for your help
03-30-2008, 08:50 AM
#14
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Posts: 3
Hey i know a lot of people dont know me on here. Im Jerry. Some people call me JMouse or Young Buck. I've been a long time onlooker but Ive been very involved in my max. Ask my good friend Ghase if you doubt me. Well Abakalen your not alone. I have the same problem with a random misfire but the code on mine never changed. I've replaced my valve covers, MAF sensor, coilpacks, spark plugs twice, installed an AFC NEO and tuned it and the code still comes and goes. I've even tried taking it to the dealer but the SES light went out by the time I got there and came back after I left. I havent found any mechanic that can tell me whats up with this car but I do have some other friends who have tried. I think Im gonna wait til the SES light comes back again and try to get it back over to the dealer. If I decide to let them fix it or if they tell me what the problem is I'll definitely post again. Good luck with yours. Let us know how it turns out. Hoping for the best for you
03-30-2008, 11:13 AM
#15
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Join Date: Aug 2006
Posts: 601
P0300 - Random Misfire - not bad coils
My car has been running pretty bad lately and getting low 21 MPG highway
Has been getting this code a lot, it would come and go, then finally today got P0302 cylinder two misfire, so i swapped the coils with cylinder four but misfire stayed in cylinder number two.
so i took the spark plug out and it looked pretty bad, with a lot of deposits on it.
I changed the plugs a little over 20K miles ago to Denso Iridium...
So i took plugs out of cylinder 4 and 6 and they are all covered in deposits, they must have misfired quite often and were causing my P0300 code.
Anyway, here's the interesting part the Bank 1 plugs (cylinder 1 3 5) looked normal, just the bank 2 ones were messed up (cylinders 2 4 6). Also when looking at the long and short fuel trim through obd-2 the bank 1 was normal but the bank 2 long fuel trim is -11 and short fuel trim is around -10 trying to compensate for rich condition.
on 3.5L to get to bank 1 spark plugs one need to take the intake manifold off, so once taken off i looked inside and it was so weird the runners for cylinders 1, 3, and 5, are clean and dry, but runners for 2, 4, and 6, are covered with oil (they are the lower ones on the intake)...
so that explains the deposits on spark plugs, fouling them, leading to misfire, causing the O2 sensors to see rich running condition, and probably clogging my pre-cat on bank 2.
Now the question is why do i have oil in my intake manifold?
the car now eats 1 quart of oil for every 1K miles, if it burns it all why there's no blue smoke out of exhaust? (are the cats that efficient?)
I checked vacuum at idle and it's steady at 19 inches mercury.
I need to do a compression check...
But if it was bad piston rings then the oil would just burn up inside the cylinders, how does it end up in my intake? PCV valve was replaced a little over 20K miles.
Obviously oil is being sucked in by the intake vacuum, and because the VIAS (power valve) normally separates upper and lower intake runners the oil ends up in the lower runners going into cylinder 2, 4, and 6.
What do i need to fix to stop oil getting inside the intake manifold.
Oil catch can would probably help but it seems like a band-aid rather than solution.
As far as I understand -
1. Clogged pre-cats would not allow for good vacuum at idle.
2. Bad piston rings would not explain oil getting into intake. (or would they?)
3. There is no EGR, so it's not the exhaust gunking up the intake
What would bad valve guide seals do?
Does anyone have any ideas what causing the problem?
Thank you in advance for all your help.
My car has been running pretty bad lately and getting low 21 MPG highway
Has been getting this code a lot, it would come and go, then finally today got P0302 cylinder two misfire, so i swapped the coils with cylinder four but misfire stayed in cylinder number two.
so i took the spark plug out and it looked pretty bad, with a lot of deposits on it.
I changed the plugs a little over 20K miles ago to Denso Iridium...
So i took plugs out of cylinder 4 and 6 and they are all covered in deposits, they must have misfired quite often and were causing my P0300 code.
Anyway, here's the interesting part the Bank 1 plugs (cylinder 1 3 5) looked normal, just the bank 2 ones were messed up (cylinders 2 4 6). Also when looking at the long and short fuel trim through obd-2 the bank 1 was normal but the bank 2 long fuel trim is -11 and short fuel trim is around -10 trying to compensate for rich condition.
on 3.5L to get to bank 1 spark plugs one need to take the intake manifold off, so once taken off i looked inside and it was so weird the runners for cylinders 1, 3, and 5, are clean and dry, but runners for 2, 4, and 6, are covered with oil (they are the lower ones on the intake)...
so that explains the deposits on spark plugs, fouling them, leading to misfire, causing the O2 sensors to see rich running condition, and probably clogging my pre-cat on bank 2.
Now the question is why do i have oil in my intake manifold?
the car now eats 1 quart of oil for every 1K miles, if it burns it all why there's no blue smoke out of exhaust? (are the cats that efficient?)
I checked vacuum at idle and it's steady at 19 inches mercury.
I need to do a compression check...
But if it was bad piston rings then the oil would just burn up inside the cylinders, how does it end up in my intake? PCV valve was replaced a little over 20K miles.
Obviously oil is being sucked in by the intake vacuum, and because the VIAS (power valve) normally separates upper and lower intake runners the oil ends up in the lower runners going into cylinder 2, 4, and 6.
What do i need to fix to stop oil getting inside the intake manifold.
Oil catch can would probably help but it seems like a band-aid rather than solution.
As far as I understand -
1. Clogged pre-cats would not allow for good vacuum at idle.
2. Bad piston rings would not explain oil getting into intake. (or would they?)
3. There is no EGR, so it's not the exhaust gunking up the intake
What would bad valve guide seals do?
Does anyone have any ideas what causing the problem?
Thank you in advance for all your help.
So what i would do next is swap bank 1 and bank 2 injectors and see if the code goes to bank 1 misfire.
Oil in intake might be attributes to your misfire code or you may have 2 separate issues as a few others have oil burning issues but not missfire codes necessarily.
Bad valve seals would give you blue smoke at startup as oil slowly drips in cylinder overnight and at startup you burn it off.
as for installing pistons without removing the heads might be a whole lot harder than going conventional way.
What i would do is go get a bottom end assembly from Nissan and then pull your heads and everything else and swap them onto your new bottom end that is already assembled.
You will need 2 head gaskets, new head bolts, new rocker cover gaskets, thermostat exhaust gaskets and intake plenum, some good silicone 2-3 tubes, , cam seals if you want as cams have to come off, etc
Also did you get dealer plugs with the correct heat range?
05-12-2008, 07:20 PM
#16
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Finally had leakdown test done and the results:
bad piston rings in cylinders 2 and 4.
So now what?
I could have changed the head gasket myself, could have taken the head to a machine shop...but if the rings are broken and scored the cylinder walls, that gets beyond the scope of DIY...
so i was just thinking of getting a complete engine from a junk yard...
NisTech,
I value your suggestion of just getting a bottom end assembly from Nissan, but unfortunately it costs more then a complete engine from junk yard.
Plus I got almost 130K on my maxima, so i simply just can't justify getting new engine from Nissan (even if i could afford it), while i could get one with under 40K mi from 2006 Maxima from local junk yard for $1000 dollars...
As far as i know they should be interchangeable, but could someone please confirm that the engine from 2006 auto will bolt up to 2002 six speed manual...
Thanks.
Nissan quality is definitely not what it used to be...i will not be buying any more Nissan's
I got 97 Quest with 140K and no problems with the engine whatsoever...(the van has even been totaled once and it was front impact too)
vg30e in the Quest is not advanced at all but it just works.
From engineering point of view VQ35DE is way better, lighter and more advanced but i guess they used the cheap stuff and made in CN to cut on the costs...
bad piston rings in cylinders 2 and 4.
So now what?
I could have changed the head gasket myself, could have taken the head to a machine shop...but if the rings are broken and scored the cylinder walls, that gets beyond the scope of DIY...
so i was just thinking of getting a complete engine from a junk yard...
NisTech,
I value your suggestion of just getting a bottom end assembly from Nissan, but unfortunately it costs more then a complete engine from junk yard.
Plus I got almost 130K on my maxima, so i simply just can't justify getting new engine from Nissan (even if i could afford it), while i could get one with under 40K mi from 2006 Maxima from local junk yard for $1000 dollars...
As far as i know they should be interchangeable, but could someone please confirm that the engine from 2006 auto will bolt up to 2002 six speed manual...
Thanks.
Nissan quality is definitely not what it used to be...i will not be buying any more Nissan's
I got 97 Quest with 140K and no problems with the engine whatsoever...(the van has even been totaled once and it was front impact too)
vg30e in the Quest is not advanced at all but it just works.
From engineering point of view VQ35DE is way better, lighter and more advanced but i guess they used the cheap stuff and made in CN to cut on the costs...
05-13-2008, 07:15 PM
#18
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Join Date: Aug 2006
Posts: 601
how about those exhaust mainafolds? It's just a matter of time till they leak
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