P0301. Replaced coil & spark plug, now it's returned.

slight shaking on startup?
how low was the antifreeze?
did you fill the antifreeze to the full mark and drive it 50 miles?
maybe bad coil pack again.... ?
Go to auto parts and get the stuff that detects gasses in your antifreeze?

 

Combustion Leak Detector

 

Do not use that unless your sure it's the head gasket.....and get the stuff that's $50 or more...... last resort if your desperate.

 

https://www.oreillyauto.com/detail/c/lisle/chemicals---fluids/leak-detectors---sealers/27fbee18b299/lisle-combustion-leak-detector/lis0/75500

 

https://www.oreillyauto.com/detail/c/lisle/chemicals---fluids/leak-detectors---sealers/27fbee18b299/lisle-combustion-leak-detector/lis0/75500

 

Leak detector test checks for Exhaust Fumes in coolant, but that’s all? Leak down test will nail all the possibilities, I believe there’s eight .

 

Can you spell out your hypothesis a bit more? Are you saying that stuck rings contribute to EGR/intake clogging, or are you suggesting carbon clogging is happening somewhere else? Besides the point @The Critic made about 14/15 also having HG failures, if your hypothesis is related to EGR then why do some 2014-2015 also have significant EGR/intake clogging? And if stuck rings are a main cause of HG failure, that would imply that high oil consumption would be a precursor to HG failure, and I think several failures haven't reported significant consumption.

 

There’s a special gauge set for leak down test, and you need compressed air. You can do a poor-man version, without the valve set, just using a compression tester hose with its valve removed. Full disclosure: I’ve never done this myself, just reading up.

 

We seem to be driving a lot of traffic to that guy's leakdown-test video even though it's not at all hard to find better ones.

Part of the problem with the "Eric" video is not really his fault, it's that the specific "U.S. General" tester he's demonstrating is built for a ridiculously low test pressure, so even when it is showing you leakage, you can't easily listen for where the leakage is, which is one of the main reasons you do a leakdown test. You can see in his video (and somebody else's showing the twin "Pittsburgh" tester) that these things are built so the outlet gauge is full scale when the inlet one is barely over 15 psi. The other 85 psi available on the inlet scale are just for show.



Superficially, those testers look like the Snap-On one in the first video above, until you look at the inlet gauge and see that it is built so full scale on the outlet is near 100 psi on the inlet. That's the way the non-toy ones are built, and means you can pretty easily hear where the leakage is going if there's an issue.

You can also get good results with the more old-school sort of tester that just uses two identical pressure gauges (instead of putting a fancy backward-reading % scale on the outlet one). You just look up both readings on the chart in the lid of the case to see what it's telling you. An advantage there is you're not limited to just one choice of inlet pressure. Again, though, you'll normally be using somewhere near 90 or 100 psi of pressure, not 15.



The strangest thing about the "Eric" video is the way he even notices the tester isn't giving him the useful result it should give, and comments on it, then kind of shrugs it off, doesn't step back to figure out why, and posts the video that way.

 

From here on I’ll just page you chap.

 

Ok, but neither of those videos have Beavis & Butthead quotes like Eric's does.

I've been on the fence for a few weeks about getting one of those OTC devices (around $80-90, I think) just to see the state of health when I get around to replacing spark plugs. But even at nearly 159k, I have no signs of head gasket issues so it's probably not really worth it.

 

nah, op rather have a bottle of bars than $1,500 bill. Let the clogging be his next research after using the bars.

 

I think at the time I made this post I even saw some listings closer to $50-60 (in the OTC flavor or the obviously-same-thing Proto flavor).

FWIW, I am in favor of getting baseline numbers around routine spark plug changes and watching how they change over time, rather than just starting when there seems to be a problem.