Random Misfires 2010 NonPP SHO, Diagnosis -- No Oil in Engine

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FearlessAZ

New member
Been trying to track down the cause of random misfires lately. Just after Thanksgiving, got a random misfire on cylinder 5 while driving back from Tucson. Cleared it and haven't thought much of it. Figured it was cause the wife put in 87 instead of 91. Just a couple days ago got another random misfire but on cylinder 2. Went to clear it and noticed a p0300 code as well. Spark plugs are still fairly new. Maybe 12K-15K at most. I will dig in to it more later when I have some free time. Just scratching my head on it.
 
Plugs and injectors are the usual culprits, sometime leaky VC gaskets.  Interesting it showed on 2 & 5, as they fire sequentially.  Waste spark is not used in this ignition system, so ...  Poor fuel/insufficient octane can also be culprits, as you have noted.
 
SHOdded said:
Plugs and injectors are the usual culprits, sometime leaky VC gaskets.  Interesting it showed on 2 & 5, as they fire sequentially.  Waste spark is not used in this ignition system, so ...  Poor fuel/insufficient octane can also be culprits, as you have noted.
Click to expand...
Manu maybe "troubleshooting section" perhaps for better traction! Thanks!  Z  :)
 
SHOdded said:
Plugs and injectors are the usual culprits, sometime leaky VC gaskets.  Interesting it showed on 2 & 5, as they fire sequentially.  Waste spark is not used in this ignition system, so ...  Poor fuel/insufficient octane can also be culprits, as you have noted.
Click to expand...

She knows that I stress 91 only and nothing less. And she knows I made a deal out of it the one time I found out. It is entirely possible she did it again and did not tell me.

That is good to know because they are both next to eachother. I will keep my eyes peeled.

Macgyver said:
Were they all gapped the same ?
Click to expand...

Yes. All were gapped at about .029. When I have time, I will go through and recheck the gap and double check the plugs.

AJP turbo said:
Im suspecting coils due to the age
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That is very possible too. I know They are still the factory coils. I can check them out when I check the plugs. Any things to look for specifically? I know I am overdue for a data log now that all the new parts have had time to settle and be broken in. Would that possibly show an injector or 2 starting to go out?
 
ZSHO said:
Manu maybe "troubleshooting section" perhaps for better traction! Thanks!  Z  :)
Click to expand...

Thank you. Was going to start one and just been super busy lately. Didn't mean for that post to go for more than a response. Lol
 
I had the same problem although just cylinder #6. Try swapping both coils with two known good cylinders and seeing if the problem follows. If not, the injectors are not to terribly expensive and are actually rather easy to R&R. As a bonus, you’ll get to scope your intake valves pretty easily and see their condition!
 
SHOdded said:
Plugs and injectors are the usual culprits, sometime leaky VC gaskets.  Interesting it showed on 2 & 5, as they fire sequentially.  Waste spark is not used in this ignition system, so ...  Poor fuel/insufficient octane can also be culprits, as you have noted.
Click to expand...


It has been driven a lot less lately. But I need to get it ready for a road trip in about a week. I have cleared the code a couple times. Seems it is just misfire for cylinder 2 now. I will try to get into it tomorrow. Gonna flash back to stock for the time being just in case it needs to make a quick dealership trip.
 
Cylinder 2 in the one on the rear in the middle, correct? Figured I would start at the problem. When I looked at my notes last night, Seems like I have about 15K miles on the plugs. Doesn't seem like too much to me.
 
FearlessAZ said:
Cylinder 2 in the one on the rear in the middle, correct? Figured I would start at the problem. When I looked at my notes last night, Seems like I have about 15K miles on the plugs. Doesn't seem like too much to me.
Click to expand...
Correct! Rear middle cylinder. Z

                      1      2        3

                      4      5        6

gCsvIPUh.jpg

                            Front bank of engine
 
Part lean, part rich electrode?  No buildup though.  what is the measured gap?  consistent with the other plugs on that bank?
 
Measured just about .029. Ran out of time before pulling the other plugs. I swapped the coils on 2 and 6. See if maybe it jumps. I couldn't visually see anything wrong with coil 2 but that doesn't mean much.
 
I checked it for any signs of wear. Couldnt see anything out of the ordinary. Nut there is a lot going on internally that I don't have access to see. I heard the coils tend to go around this time for the older SHOs. But it is usually one or 2. Was looking at the MSD ones about a month ago but never heard if there was any real benefit to it. But seems like a set of plugs and coils are on the list for the near future.
 
I believe we gapped to .028  when we installed. I thought it was about .029 but current gap says otherwise. I said about .029 but its about half way between .029 and .03. I couldn't find any oil around. Boot and plug just had a little grease for the install. Plug is exactly as pictured. I tried to look down into the hole but didn't see anything out of the ordinary. And nothing struck me as out of place when I pulled the plug.

My wife has been driving it since about August. I know she isnt as "spirited" as me when she drives. So I know she hasn't done any launches or hard accelerations like I have. Hell, even when I drove it, I would only do when data logging. Once I had all the work done, I babied it so it could break in correctly.
 
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