The Nissan Path

My 2006 path le threw a p0301 misfire cylinder 1. It happened when towing my boat up a hill that I go up all the time
Pulled #1 coil & plug. Found the plug fouled, so replaced the plug & coil.
Checked the other plugs & they all looked good.
Cleared code & took a drive. CEL came back on & car still doesn't have muck power. It also idles rough
Any ideas what to check next?

NVRDONE wrote:My 2006 path le threw a p0301 misfire cylinder 1. It happened when towing my boat up a hill that I go up all the time
Pulled #1 coil & plug. Found the plug fouled, so replaced the plug & coil.
Checked the other plugs & they all looked good.
Cleared code & took a drive. CEL came back on & car still doesn't have muck power. It also idles rough
Any ideas what to check next?

check the plug & see if it's fouled again
if so, do a compression & leakdown test on that cylinder

So I checked the #1 plug and it was fouled again. Checked all the other plugs and the plugs on the right bank had some fouling, the left bank just looked worn. Original plugs were replaced at 90 k and now at 134k.
I replaced all the plugs, cleared the codes and went for a drive.
Under load the cel flashes on and goes off. Stored code is p0301 random misfire on #1. Pulled #1 plug and it had a slight oil coating
Could my cats be failing again causing this problem ?

If a catalytic converter has failed and caused this problem, then chances are the damage is done to the engine. As stated, compression and leakdown tests would be recommended. Many late model Nissans use the variable camshaft timing for EGR rather than a conventional EGR valve system. If the upstream converter media starts to come apart, tiny bits of it can get sucked into the combustion chamber past the exhaust valve and score the cylinder walls.

NVRDONE wrote: Pulled #1 plug and it had a slight oil coating
Could my cats be failing again causing this problem ?

I sure hope not, but therein may lay the problem.
Time for a compression/leakdown test on ALL SIX.

Ok, so today I did a compression & leak down test
#1 has zero compression. Added oil & no change. All other cylinders have 160 psi with zero leak down.
So is this a sleeve motor or am I looking at a complete rebuild?
I will get a bore a scope and check before I decide what to do.
Maybe I should just dump it for something else

I don't have much experience, so SMJ and others with more can weigh in, but if the compression is actually zero, would that not indicate a valve issue as opposed to a cylinder issue? I would expect poor compression if the cylinder was scored, and it would get better if you put oil in.

If so, maybe you'd only be looking at top end work as opposed to long block.

t

unfortunately a valve issue can result in piston damage
a leakdown test may shed more light on this issue by indicating where the compression loss is occurring (intake or exhaust valve OR piston/ring/cylinder)
but if there is more than one of these at fault, it may not tell us any more
than we already know
sorry to bring up another concern at this time, but the only thing I can remember causing compression loss/engine damage is the failure of one or more of the catalytic converters
so there may be an underlying cause of this engine problem

If only one cylinder is at 0 psi, I would suspect a valve issue, as well. The converter issue typically doesn't focus on just one cylinder. I would do a leakdown test on that one cylinder just to see where the compression is being lost. You might just need to remove the one cylinder head, as opposed to entire rebuild.

Sort of off topic, but how do you go about checking that the cats are not on the way out the door? I see a lot of talk about these failing, plugging, disintegrating, etc. but it's always after the damage is done.

Is it possible that on the bad cylinder a connecting rod let go? Or maybe a hole in that piston?

An exhaust back pressure tester can be used to test for a restrictive or clogged converter. As far as viewing the media to see if it is breaking down, one could remove the converter for inspection. Otherwise, the only way I could think of is to remove the front O2 sensors and use a video scope.

If a rod broke, I would suspect one would hear the noise coming from it. A burnt hole through the piston is possible, but I've yet to see it on a VQ. That's why I would recommend a cylinder leakdown test.

NVRDONE, any update? hoping for good news!

Hope to get a bore scope this weekend and have a look inside

Ok got a leak down tester and a bore scope. Now how do I find tdc?
There are some white marks on the balancer and what looks like a pointer to the right / passenger side of the engine. My reading says the timing marks are on the timing chain and the cover has to be removed.
any thoughts would be appreciated