Tacoma 2007 V4 Cylinder 2 misfire

So as I have mentioned, I put new spark plugs last week. As you can see on the first two pictures, that’s spark plug on cylinder 2, where the misfire is occurring. The white top part is very dark. There was No oil though. Spark plugs for cylinder 1 and 3 are pictures 3 and 4 and they look fine to me. Spark plug for cylinder 4 does show a little red dark one on side, perhaps a fuel injector issue. But there’s something going on with cylinder 2. What would it mean if the top white part on cylinder 2 spark plug is dark like that?
 

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I agree it is probably oil getting into Cylinder #2. Now, the question is.....From where is the oil entering?

Head gasket keeps anti-freeze out of the combustion chamber. I don't think head gasket is likely.
At 180,000+ miles, the oil control ring on Piston #2 is a likely suspect. Another suspect is a scored/cracked cylinder, but that is ruled out due the positive results from the compression test.

Unfortunately, getting access Piston #2 is a MAJOR task. But probably much less cost than a short block.

If this were my situation. I'd run the electrical diagnostic first, then fuel injector. Rip into the engine as a last resort.

Good Luck.
 
mando0721 said:
Hey all, I’m new to the Tacoma world. I finally purchased my own Tacoma. A 2007 v4 with 180,000 miles. Has had only one owner the whole time. The guy took it to get maintenance every 4 months, did a car fax report to confirm it.

Purchased it a month ago and about 2 weeks ago the engine light came on. Went to autozone and got a p0302, cylinder 2 misfire. To fix the problem, it told me to change the spark plugs or the ignition coil for cylinder 2, which I did. Seemed to have improve the situation but it continued with the problem. Went to the mechanic, and they did a compression test and cylinder 2 was fine. I changed out both oxygen sensors and still have the issue.

I decided to take it to a Toyota dealer and they’re charging $190 for a diagnostic charge. Took it in on Friday and they checked it out all day Friday and Saturday and are still troubleshooting.

Service advisor said that I might need a new short block engine and that either the crankshaft or camshaft has a small leak (not sure which one) but I highly doubt it. I’m thinking it’s an electrical problem or a bad gasket. Perhaps coolant leaking?

The misfire happens intermittently, not all the time. And at most, I can drive it at a low speed. It happens a lot when I’m going past 70 miles an hour but has happened at low speeds at times. So yeah, the truck is currently at the Toyota dealer. We’ll see what they tell me tomorrow. Any ideas what it could be?

Thank you in advance!
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Did you replace the wires?
 
true, instead of removing the gasket to see if it’s bad, I can do a test. I’ll go to autozone to get the kit and do that first. Hopefully it changes color. But would a bad gasket cause the spark plug to be that dark?

And I have not replaced the wires going to the ignition coil. I did test the wires though with a multimeter and it’s working fine according to the voltage reading being the same with the other ignition coils.

And is it possible to access the piston #2? Since I’m still getting good compression on cylinder 2, I know the engine is still operational but I want to avoid it from getting worse.

Thank you all for your support, I really appreciate it!
 
Being dark means that cylinder is run cold I always replace wires then I know for sure that that link in the chain is good. If you check all the cylinders and they are all with in the same psi + or - 5 the cylinders are good but you should do a wet test also a little oil in the cylinder it should not change if it does bad rings.
 
The oil control ring on the piston can not be tested with a compression test. The rings above (near the top of the piston) will form the seal.

An oil ring is basically a scraper designed to remove oil from the cylinder wall. When the oil ring quits scraping, then extra oil will be in the combustion chamber to be burned. Inside the oil ring groove there are drain back holes for the oil to return to the sump. If these become plugged then the oil can't drain back and will find its way into the combustion chamber. The common method for the drain back or oil ring fouling is extended oil changes or poor quality oil.

The oil ain't coming from the head gasket.

Suggest getting a bore scope. Remove the #2 plug. Rotate the engine until #2 is bottom dead center. Use the bore scope to inspect the cylinder walls for any signs of scoring.

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I've seen many engines when torn down with over 150k miles have broken oil control rings. Usually it's not just one cylinder which is strange, it's nearly all of them. I'm still leaning toward a bad head gasket as the main culprit. As far as the rest of the block, its likely a crap shoot that it does need replacement for long term reliability.
 
Long story short, it was a bad fuel injector on cylinder 2. The tricky part was that it sounded like the other injectors and when checking it with a meter, the ohms and voltage were right. It was when he switched that fuel injector from cylinder 2 to 1, cylinder 1 was misfiring and cylinder 2 was fine.

He even had a machine connected to it with the fuel injector swapped and the truck running and no misfire on cylinder 2

The engine leak down test confirmed there’s nothing wrong with the engine. No leaks. Truck running perfect now!
 
mando0721 said:
Long story short, it was a bad fuel injector on cylinder 2. The tricky part was that it sounded like the other injectors and when checking it with a meter, the ohms and voltage were right. It was when he switched that fuel injector from cylinder 2 to 1, cylinder 1 was misfiring and cylinder 2 was fine.

He even had a machine connected to it with the fuel injector swapped and the truck running and no misfire on cylinder 2

The engine leak down test confirmed there’s nothing wrong with the engine. No leaks. Truck running perfect now!
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So cool I thought that that plug looked cold that would be not enough fuel so easy fix hard to find! Thanks for the up date! Glad you did not go for the short block!
 
Refer back to Post #5 for possible causes of the misfire.

Always, always, always work through the simple causes FIRST.

Glad you found the problem and the fix wasn't too complex.
 
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