2014 with random misfires

Just curious if anyone else has ran into this issue. I have a 14 that I recently got the tune dialed in remotely with Lund. 3.6 KB and full bolt ons. I installed a mechanical boost gauge and went out to do a couple pulls to make sure it was reading right. After I was done and went back into town I noticed the car was missing pretty badly. I got it home and let it idle and you could hear the missing but there was no check engine light but when I checked codes in the ngauge I got P0300.

Just curious where to start looking. Was going to pull plugs and start there, I put TR7s in last spring gapped at .028. I do notice my AFR2s are jumping all over the place where my AFR1s are looking normal.

Also not sure if it's worth noting but I saw the drain for the cowl drains in the middle of the fire wall and was dripping down my exhaust because i could hear it sizzling and I was able to see where it was coming from. Didn't know if maybe an o2 got wet or something. Anyways, any suggestions are appreciated.

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Check the crank bolt and see if it has the proper washer on it and tighten it to approximately 100 ft-lbs. Another member and myself had random misfire problems and this was the culprit. My crank bolt was finger tight and the other members was missing the washer or had the wrong one.

Do you have O2 extensions?
These cars don’t like the extensions and the stock ones will reach with headers.
How old are the O2s?
-J

Have 30xxx miles on the car and still factory o2s. No extensions on them

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Stock cats?
With 30k and a tuned KB, I’d look at stock 30k cats as a liability. If they’re gone, I’d replace O2s
Good luck.
And post some pics! Gotta love that KB whine!
-J

Just an update. Put new plugs in and didn't fix the issue. I did, however, remove the boost gauge from the vacuum lines and the car runs so much better but still had a random misfire or stutter while driving. I'm going to rerun and check all vacuum lines and see if it clears out

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Mine started doing this after I ported the intake. I was told by a tuner I need to get a tune adjustment for intake volume.

Maybe it is vacuum? Only common denominator.

Yeah it was a vacuum leak. I redid the lines and it runs like a top and even starts smoother

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CrimsonStang said:

Yeah it was a vacuum leak. I redid the lines and it runs like a top and even starts smoother

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Having a similar issue, did you happen to throw the wrench light? By redo do you mean replaced or did you disconnect and reconnect everything. Any spot in particular to check.

SteveWK said:

Check the crank bolt and see if it has the proper washer on it and tighten it to approximately 100 ft-lbs. Another member and myself had random misfire problems and this was the culprit. My crank bolt was finger tight and the other members was missing the washer or had the wrong one.

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Happened to me when I bought my car from carmax. Either the guy they got it from went back to stock and did a half ass job or the factory missed the washer.

These engines are VERY sensitive to crank signal. If its not a clean signal it gets pissed. Car will laugh off 900whp, but God help you if you have a dirty crank signal.

lexustech48 said:

Happened to me when I bought my car from carmax. Either the guy they got it from went back to stock and did a half ass job or the factory missed the washer.

These engines are VERY sensitive to crank signal. If its not a clean signal it gets pissed. Car will laugh off 900whp, but God help you if you have a dirty crank signal.

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You referring to the harmonic balancer crank bolt? Or something else.

Pauliejr said:

Having a similar issue, did you happen to throw the wrench light? By redo do you mean replaced or did you disconnect and reconnect everything. Any spot in particular to check.

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Honestly I don't know where it would have been but I put new lines for the line going from the lower intake to fuel rail pressure sensor and the T fitting going to the boost bypass. I also put zip ties on each connection for added insurance. I did not get a wrench or even a CEL. I had to check codes with my ngauge to see the misfire

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CrimsonStang said:

Honestly I don't know where it would have been but I put new lines for the line going from the lower intake to fuel rail pressure sensor and the T fitting going to the boost bypass. I also put zip ties on each connection for added insurance. I did not get a wrench or even a CEL. I had to check codes with my ngauge to see the misfire

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My sct only pulls DTC codes which it’s not throwing.

Pauliejr said:

My sct only pulls DTC codes which it’s not throwing.

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Join forscan and download software. You need to buy a USB DLC2 connector, but you'll be able to do a wide variety of things including view live data from the engine

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