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Discussion Starter #1
I just finished replacing the spark plugs using the method described in the following thread, where one does not remove the intake plenum.

www.thenewx.org/forum/showthread.php?t=43021

Thanks to Snow and Surf and Xterramex, I figured out that the seal around the rearmost plug on the passengers side valve cover was leaking, filling that plug well with motor oil. I am sure that when I removed the old plug, a bunch of the oil dripped into the cylinder.

When I got it all put back together and started it up, I got a lot of blue smoke and a rough idle. After a few minutes, the smoke stopped. I still have the rough idle and the "Check Engine Light" flashes, stays on then goes away. The CEL then comes back, flashes and goes away. The engine runs rough and does not accelerate smoothly. I drove it to a nearby O Reily's where they kindly read the codes. They could only find one, P0300. Looking it up, on this forum, I find it indicates "multicyl misfire".

I can see several possible causes.

I am wondering if the misfire is related to oil that got into the cylinder. I am especially concerned by the posts about burnt out cats due to misfires.

I am also wondering if there may be some connection problem between the coils and the plugs, say with the "spring" in the extension between the coils and the plugs. I had smeared a bit of silicone dielectric grease on the two ends of the "spring".

Lastly, I am wondering about the gapping of the plugs (NGK PLFR5A-11). All of the plug gaps measured about 0.040 inch so I opened them up to 0.043 as indicated in the Haynes Manual. My gapping tool and my Mitotoyu digital calipers both agreed on the gap measurements.

I was not able to find anything left unconnected. I will recheck tomorrow when there is more light.

Does anyone have any ideas?

Thanks in advance.

Phil
 

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The blue smoke is normal from the oil, the ngk plugs are pre gapped....with the engine cold your going to have to put the gap the way they came. The silicone on the spring might cause an issue. Re check the connectors are pushed in all the way
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Discussion Starter #3
So I should pull all the plugs and re-gap them with a smaller gap? I can try washing off the silicone using some alcohol at the same time.

Are the plugs "re-useable" or should I get some fresh ones? My concern is if the crush washers will still work after being installed once. I am Okay with spending another $60 to get it right. That's still way less than what the dealership would have charged to do the job and what replacing even one cat would cost.

Thanks again.

Phil
 

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Assuming the connectors are all plugged in, the oil in the cylinder has fouled that plug. Guaranteed. You will need to remove the plug and clean it with brake cleaner and some sand paper. I'm hoping that's all. If there was a lot of oil, it could have caused a cracked piston upon compression. That's a VERY bad thing. Hopefully it's just the fouled plug.
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also, make sure you remove or install the plugs with a cold engine..... a hot/warm engine will not allow them to sit correctly.
 

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Discussion Starter #6
I drove about 5-7 miles, round trip, to get to O Reily's so I am guessing the piston is probably Okay?

I will have to run some errands today so I will just pick up a new plug. I figure if I remove the coil and extension, get the new plug ready to install, clean around any oil that is around the plug that is installed, remove the one that is in there now and immediately install the new one, it would minimize the time for any oil to get into the cylinder and the new plug should not get fouled with oil.

If I spray brake cleaner or carb cleaner into the spark plug well to flush out any oil, with the existing plug in place, would it hurt any of the seals or anything else nearby?

Thanks again.

Phil
 

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Discussion Starter #8
I managed to change all the plugs with new NGK Laser Platinums again this afternoon. I flushed the plug well that had the oil with carb cleaner (plug still installed) and then poked paper towels down into the well to soak up the liquid. I could not get the paper down around the plug itself. I got the last bit of liquid out by putting the spark plug socket in, withdrawing it and wiping it off about 20-30 times until I did not pick up any more fluid. I also checked visually using a flashlight.

I took the two rubber boots off each of the coil extensions and flushed everything with carb cleaner and put it all back together again. I noticed a potential problem with the rubber boots but that did not turn out to be the issue, I don't think. I will start a separate post about the rubber boot problem and post pictures later.

Unfortunately, I still get the rough idle and the flashing Check Engine light. I am going to bet that it is still a misfire. At least I didn't get any smoke this time.

I will ask one of my coworkers if I can borrow his super-duper code scanner. If that doesn't provide any new information, I guess I am stuck going to the dealership to get a diagnostic done. I am about 13-14 miles from three Nissan dealers. Would I be cooking the catalytic converters or doing any other great damage if I drive it that far (and back, maybe)?
 

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Discussion Starter #9
I have been doing some more reading on this forum. I am suspecting two possible causes for the SES.

1) The O2 sensor(s) may have become fouled from all the oil that had accumulated in the plug well and drained into the cylinder the first time I changed the plugs this weekend. My symptoms are much like those described in the second post of the thread below. I also intend to follow the recommendations to not drive it until I know I won't damage the cats and raise my repair costs even more.

www.thenewx.org/forum/showthread.php?t=39144&highlight=coil+pack


2) One or more of the coil packs may have been damaged when I was doing the work. I would check them as described in the ninth post but if it is multiple bad coils, swapping them around would not help find the problem.

www.thenewx.org/forum/showthread.php?t=64547&highlight=coil


I am leaning towards #1 because I got the P0300 code which is not specific to a particular cylinder and it is not likely that I damaged multiple coil packs. None of the coil packs were dropped and none of them show any signs of damage. Also, one of the posters on this forum commented how rare it is for the coils to fail.

If I can borrow my co-workers super-duper, do-it-all code scanner, would I just scroll through a bunch of menus until I find O2 sensor values?
 

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I have been doing some more reading on this forum. I am suspecting two possible causes for the SES.

1) The O2 sensor(s) may have become fouled from all the oil that had accumulated in the plug well and drained into the cylinder the first time I changed the plugs this weekend. My symptoms are much like those described in the second post of the thread below. I also intend to follow the recommendations to not drive it until I know I won't damage the cats and raise my repair costs even more.

www.thenewx.org/forum/showthread.php?t=39144&highlight=coil+pack


2) One or more of the coil packs may have been damaged when I was doing the work. I would check them as described in the ninth post but if it is multiple bad coils, swapping them around would not help find the problem.

www.thenewx.org/forum/showthread.php?t=64547&highlight=coil


I am leaning towards #1 because I got the P0300 code which is not specific to a particular cylinder and it is not likely that I damaged multiple coil packs. None of the coil packs were dropped and none of them show any signs of damage. Also, one of the posters on this forum commented how rare it is for the coils to fail.

If I can borrow my co-workers super-duper, do-it-all code scanner, would I just scroll through a bunch of menus until I find O2 sensor values?
It's not going to be an o2 sensor. It will be a cylinder misfiring. The ecm sets a P0300 first to identify a misfire, and THEN works on identifying the specific cylinder. Better scan tools like the SnapOn Modis or OTC Genyssis for example can access individual PIDs to show the misfire count for each cylinder that can then help know which cylinder is the offending culprit.

If the CEL is flashing, that indicates a MAJOR problem that can and will cause failure of the cat converters. I would double and triple check ALL coil connectors, and look VERY closely at all vacuum lines to make sure that you did not knock one loose or break a nipple. I'd still be nervous of what I mentioned about starting it with oil (incompressible liquid) in the cylinder and cracking a piston. If you can not identify any causes, tow it to a pro. Driving it as is can easily cost WAY more in damages then the price of a tow to a reputable diagnostic shop.
 

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Discussion Starter #11
Thanks for the advice Surf and Snow. I did the plug change myself and am now trying to do the diagnosis myself, with the help of people like you, since I know I can't afford to replace the cats.

I think the Actron (?) that my co-worker might be able to get that level of access. He said that it is a professional model where you can change all kinds of settings with it and get into real trouble.

I will have a look at the hoses since I haven't tried that yet. I could tell that all the coil connectors "snapped in". I could open the connection and check that the pins aren't bent to one side. I have seen that happen on the industrial equipment I design at my day job.

Would it be worth spending a few minutes checking each O2 sensor output with a DVM? I would expect the two front ones to give similar output voltages and the two rear ones to give similar voltages.

I don't think I will get to any of this until the weekend since I am now supposed to make arrangements to fly to Toronto for a funeral on Wednesday. Hopefully I can sneak in a visit to Tim Hortons to get a fix :)
 

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Would it be worth spending a few minutes checking each O2 sensor output with a DVM? I would expect the two front ones to give similar output voltages and the two rear ones to give similar voltages.
Volt meters are pretty useless for checking O2 sensors, because 1.) the switching is faster than a DVM can catch. You really need to use an Oscilloscope to view the output, or much simpler just look at the cycling on your friends scan tool. And 2.) O2 sensors usually use shielded wire, and if someone tries to stab a probe in a wire than can cause it to short out.
 

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Discussion Starter #13
Thanks again.

It is good to know about the shielded wire. I normally stick some long thin probes into the connector.

I was wondering if the DVM would get freaked out by the O2 sensor waveform. I found someone who had posted "scope screen shots" of the four O2 sensor outputs and the waveforms were pretty complex. If I have to, I can borrow a scope from work too.

Take care.
 

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Discussion Starter #14
Well I finally got back from the funeral and got back to work on the X.

I found that I was in too much of a hurry and forgot to plug the wire harnesses back onto the three driver side coils. After re-plugging them, I still got a (non-flashing)SES. After clearing the SES by unplugging the battery, the SES did not come back. I was able to drive it for over 7 miles with smooth (hard) acceleration all the way up to 6000 rpm with no sign of misfires.

I think the cause of the flashing SES after the first time I changed the plugs was due to a misalignment between the coils and their associated "protector". I give more details in the thread linked below.

http://www.thenewx.org/forum/showthread.php?p=1285930#post1285930


Thanks for all the great help and advice.
 

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Discussion Starter #16
It was already dark when I got the driver side plugs and coils in. I went inside to get a long sleeve jacket to cover up. I was wearing a short sleeved T-shirt so the mosquitoes were feasting on my arms and back. When I came out, I guess I started working the passenger side.
 
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