SOLVED/REPAIRED - Misfire Mayhem - P0301, P0302, P0300

I would want to look at timing components, the chain "shouldn't be stretched/worn too much at that mileage but it's certainly worth checking or replacing the timing set while your there. Oil maintenance plays the biggest role in timing chain life so depending on how that was kept up with can be the difference in a timing set lasting only 150k mi or over 300k mi.

 

To update you guys: it was the head gasket. It was mostly between the cylinders, so only a minimal amount of coolant was leaking and thus not emitting white smoke.

What still baffles me is why I was only getting a cyl 1 misfire for so many weeks before it moved to both cyl 1 and 2.

My mechanic also said that the entire gasket was starting to go, so even cyl 4 was not immune from at least a little compression loss, and yet no cyl 3 or 4 misfires. Good news is that the 2TR-FE short block and crank are solid and there is no long-term damage to the cylinder headers. I guess I lucked out in that department.

 

Also, want to give a shout out to leak-down testing over (or at least along with) compression testing (hopefully without not pissing too many people off).

Artificially inflating the pressure in a TDC cylinder absolutely tells you a sh*t-ton mechanically.

 

Wow that was BLOWN, looks like the other cylinders were leaking across as some well.
Wonder if it was overheated at some point.

Was the head still flat?

As for why the misfires only picked on cylinder 1 who knows, maybe 2 still had enough compression to still fire ok enough to satisfy the PCM.
When you start getting more than 1 cylinder misfiring the PCM has a hard time determining which cylinders are misfiring so it's not always very accurate with multiple cylinder misfires.

 

Right on, man. You had a feel for what was going on and you stuck with it. Turning out to be a head gasket is pretty bizarre -- getting to observe the misfire spreading to another cylinder during your diagnostics.
In hindsight, were there any other indicative symptoms that got skipped which, now resolved, are apparent through their absence?

 

I don't think so completely, no. It was definitely machined, but to be honest, didn't ask my guy if there was news from the machine shop on if/how bad.

These codes and lack of other signs drove me absolutely nuts..

 

Wow, that could explain 95 psi on at least a couple cylinders

At least you found it, good job

 

Great question: Absolutely! You gotta eat to grow, you gotta learn to be better..

1) After the very first swap of coils and plugs (with cyl 1 having #3 plug and #4 coil) and P0301 only showing up again, I should've immediately crossed off plugs and coils especially after multimeter testing the leads going to the coil packs and the injectors and all the voltages showing normal. But problem came back p0301

2) Injector/spacer: Should be nothing wrong with the spacer OR the injector if you're not getting any too lean or too rich codes or any injector-specific codes. Replaced injector spacer and swapped injectors, but problem came back p0301

3) Spark: check. Fuel: check. Now we get to compression. The truck isn't burning oil - consumption is normal and no smoke/smell. As far as I can tell, it's not burning coolant either - no white smoke or significant consumption, and it's not overheating in my hands. Running compression only test and I'm getting 95 max on all cylinders. Something's off here but still getting only p0301. So it must be me or the test kit for the weird results. Aside from the problematic cyl 1, how could cyl 2 and cyl 3 and cyl 4 be registering high-80s to mid-90s PSI and NOT pop any codes? Must be something else. Continue driving the truck and trying to test further and NOW the problem spreads to cyl 1 AND cyl 2. WTF!!!! WTF WTF WTF WTF WTF...

4) Do the VE test, everything's fine. should have increased the probability of it being the head gasket problem especially now that I'm registering two adjacent cylinders misfiring

Now, leak down test is done at 100 PSI. At the end, when I tested cyl 4, it had the lowest loss rate of about 7-8 PSI (even though the gasket around cyl 4 was clearly on its way out too). 100-7=about the PSI I was registering when I did the compression test early on, even though a clean compression result would've been 150+

My hunch and lesson learned is that if I jumped to getting a leak down tester and trying it at the same time of the compression test (very early on and only p0301 popping), I would have shown similar results to cyl 4 at the end, across all cylinders: 5-8 PSI lost during leak-down, max mid 90s PSI compression test. So leak down would've seemed somewhat normal? Wrong, for the fact that, with all the plugs removed during the leak down test, in absolute TDC for the cyl you're testing, and while listening very carefully to each plug well, I would've heard the air pressure going into one cylinder and leaving through another's spark plug well. Gather your things, chug your drink, head for the exits, because the game is over - the HG is gone leaking between cylinders. And if it wasn't the HG, and it was let's say the valves were gone, the leak down would have pointed that out too.

At the end of the day, there were no physical signs of HG damage, the code kept coming back p0301 before spreading. Should have followed my gut and ignored coils/plugs after round 1, and given the mileage should not have been side-tracked by the injectors, and after weird compression results, should've ignored the complete lack of codes and symptoms and got me a leak down tester (no shop loans one out around me). It's just odd: on one hand, ignore the injectors because no injector or rich/lean codes, on the other hand, ignore the lack of misfires in 3 cylinders and follow the compression results to leak down testing.

Either way, the truck is back up and running now after I gave it to the shop. I would've liked to try my hand at doing the repair myself but didn't have another car to use while taking my time with the work.

 

Man, thank you for the summation/final thoughts. And I owe you an apology for pushing coils (and even getting kinda pissed) because of: the novelty, potential for user error, lack of distinct head gasket failure symptoms. When I did the scratch work to see that none of the coils finally landed on a cylinder that then started misfiring, I knew I was off but it was the best guess I had so it was all I could push for.

Well. I love these moments, genuinely. I love when stubborn f*ckin dudes stick with their nah, it's something else and turn out to be right in the end. Its an awesome display of perseverance, and I'm a big believer in intuition when it comes to diagnostics. So yeah, thank you for hanging in there, and for posting up/keeping us appraised. Its really cool. Consider me a fan, and I'm sorry it cost yuh a head gasket. fuckin. Good job, man.

 

Glad it's fixed and definitely appreciate the detailed updates. Lotta good info here for the community.

 

You have to remember trying to remotely diagnose a vehicle is really hard, it's not always the easiest thing to do in person even for someone that does it all the time.

Having the vehicle in front of someone that knows what to look, listen, and smell for is a huge difference from that same person looking at it from accross the internet and going by the tests the owner did and the data they provide.

Granted alot of people on the internet are quick to tell you to fire this or that part at it because "I had the same problem and that fixed mine", I'd rather do the tests and be confident in the diagnosis before beginning to replace parts or tear something down.
Sometimes that causes us to go down rabbit holes which takes time but in the end we usually arrive at the right place and try to use those lessons to be better/faster at the next diagnosis.

How would you have felt if everyone told you it was the headgasket and you tore it down only to find nothing wrong with it? In the end you did all the right tests (maybe not in the "right" order but there isn't always a clear "right" order of testing in diagnostics) and in the end came to the right conclusion, in the end that's all that matters.

 

With the first gauge at 100 psi and the other at 7 psi, we would call that 7/100 and it more closely represents a 93% loss not a 7 psi loss, though that is not really accurate as it is only measuring leakage relative to a fixed orifice size. While the numbers are meaningful for ascertaining severity, your ears identify the leak source.

I always use both compression tests when troubleshooting cylinder issues. Each tells a different story.

 

No worries at all. At the end of the day, I felt like I was up a river without a paddle, so I was absolutely looking for any advice I can get. I just knew what I had already done correctly, and wanted to make sure I wasn't making any other mistakes on my way to an answer.

Also, I'm very happy to have this information up for the community to be able to utilize. Even though this was my first time interacting with TW, I have been an active reader for years. TW has been a great resource for me for everything from regular maintenance schedules, to common mistakes/tips people make/have, to advice on aftermarket power inverter installs. Glad I can be a tiny part of it now.

 

First gauge just under 100 PSI, the other at 93ish, so 93/100 or ~7% loss.

I know how to read gauges and do math.

 

Sorry, just assumed that, as 93/100 doesn't really seem enough leakage to cause misfires or dynamic comp readings of 95. With an .040 orifice, most would consider 90/100 pretty good

 

Wanted to post up again to thank you. Our tacoma, base 2.7, has also been shitful with performance. I did the full exhaust line because it leaked and was rusty from NC. Done plugs and cleaned injectors. Got new coils sitting on the shelf waiting for it to come home from Florida (family trip). Even did timing -- made a whole write-up/story on that. But I decided a long while back that if timing didn't fix it I'd just go off and do the head. I've got good compression at 150ish across all 4 cyls, but nowhere else to look. Besides, if I'm wrong I'll still get better compression and performance.

I'm (as you've noticed) tree-shade with my diagnostics due to lack of equipment. Funny, since I used to work on Abrams tanks and that had a full onboard diagnostics set-up. turbines and diagrams, yada yada. ah well. I have a feeling I'll find my issue in the head -- our trucks exhaust smokes more than I think it aught to on start up, and vibrates too much at idle in drive. Plus, she feels weirdly gutless.

So much to say this thread has been inspirational/motivational. Because it was a weird presentation of a bad head gasket on a lower mileage truck.

 

The biggest gains (and reliability) that can be made in the head from the 3RZ to the 2TR were the hydraulic roller rockers and VVti (likely the reason Toyota upgraded). Not saying there aren't gains to be made, but don't expect much bang for the buck.

Want big gains? Go boost!

 

There's big gains to be made from properly sealing valves and removal of misfires
At this rate I won't get a to boost a car 'til I'm retired. But hey, I finally set up my shop vac to handle drywall dust. That's equally rad, right? I've almost finished removing all the cloth wire in our house too! That's.. life preserving... so the potential for rad stuff is there.