P0302 cylinder 2 misfire

[la_scanner]

2007 Toyota Yaris:

Check engine light came on, P0302 came up on the computer which indicates a cylinder 2 misfire. Vehicle taken to the mechanic and he wants to put in a new coil and replace the four spark plugs. I did not have the work done because the mechanic stated that the four spark plugs are past their time.

The car has 134,000 miles. In 2017 at 107,000 miles, all four plugs were replaced by Toyota. As we all know, these should go about 100,000 miles.

Should I just go with what the mechanic is saying, whether he does it or someone else? Personally I feel like there is some other underlying issue. In 2009. diesel fuel was put into the car. The cat was replaced and so were the spark plugs. So, in this cars lifetime, it has had the original plugs and replaced twice and now ready for a third time. The battery in the car has been replaced either four or five times. Has had a new fuel injector, alternator replaced. Also, throttle plate cleaning. Are these list of things related to the coils and/or plugs?

Oh, and does anyone have toilet paper?

Thanks!

[WeeYari]

Do you have your own OBD scanner? If so, you can swap cylinder 2 coil with the one from another cylinder. If coil is bad, you should throw a new code for the cylinder the #2 coil has been moved to. Coil removal is easy, just one bolt.

[la_scanner]

I do have a scanner. I will try this and get back to you.

In the meantime, the code has not shown back up after being erased about 20 miles ago.

[WeeYari]

Hiccups happen. That is why whenever I throw a code, I'll reset and wait for a reoccurrence.

[la_scanner]

Hi again...

Okay, so I swapped #2 with #4. I got on the freeway, sped up several times and on the way back home the check engine light came on. Actually, right when it went on I felt the vehicle lose power. It's neat to see this first hand.

Being that the spark plugs have less than 30,000 miles on them, I think I should be able to get away with only replacing the coil? What do you think?

Amzon has the coil for what I believe is a great price. $54 https://www.amazon.com/Denso-6731306-Ignition-Coil/dp/B002YT55L4/ref=sr_1_14?keywords=Denso+ignition+coil&qid=1584234701&refinements=p_89%3ADenso&rnid=2528832011&sr=8-14

[rayfloyd170]

Hi again...

Okay, so I swapped #2 with #4. I got on the freeway, sped up several times and on the way back home the check engine light came on. Actually, right when it went on I felt the vehicle lose power. It's neat to see this first hand.

Being that the spark plugs have less than 30,000 miles on them, I think I should be able to get away with only replacing the coil? What do you think?

Amzon has the coil for what I believe is a great price. $54 https://www.amazon.com/Denso-6731306-Ignition-Coil/dp/B002YT55L4/ref=sr_1_14?keywords=Denso+ignition+coil&qid=1584234701&refinements=p_89%3ADenso&rnid=2528832011&sr=8-14


You can replace the defective coil and you're good to go. but if i were you, you may replace the plugs too, they are cheap and it pays to replace them too. Manual says you can go up to 160k KM or 100K miles.

Where i sent my car previously (under warranty) they replaced them every 20K KM (at Toyota Service Center) and i happened to ask the mechanic about it. He said what is in the manual is if you are running normal RPM but in Saudi we average at 120-140kph at 3500-4000rpm since we usually drive on a freeway hence the need to change them earlier than required.

Right now i do my maintenance and replace plugs by myself at around 30-40K KM interval...

[WeeYari]

Where i sent my car previously (under warranty) they replaced them every 20K KM (at Toyota Service Center) and i happened to ask the mechanic about it. He said what is in the manual is if you are running normal RPM but in Saudi we average at 120-140kph at 3500-4000rpm since we usually drive on a freeway hence the need to change them earlier than required.

That is pure BS. Someone is making easy money off of you wasting yours.

[WeeYari]

Okay, so I swapped #2 with #4. I got on the freeway, sped up several times and on the way back home the check engine light came on.

You didn't indicate if the code has now moved to cylinder 4. Has it?

[la_scanner]

It's still showing the same code of P0302.

[WeeYari]

So switching the coil did not move the problematic cylinder. Therefore there is nothing wrong with your coils. Next step is to perform the same switching exercise with the cylinder 2 spark plug.

[la_scanner]

So switching the coil did not move the problematic cylinder. Therefore there is nothing wrong with your coils. Next step is to perform the same switching exercise with the cylinder 2 spark plug.

I should have already mentioned this, but I swapped it already.

[WeeYari]

My next thought would be injector issue, but you've stated they've been replaced. This appears to go deeper than I can advise on.

[la_scanner]

Okay, thanks for getting me this far. I better ask though, was I supposed to switch any thing with the plug/wires? I don't think I would have been able to anyway, too short to move around.

[WeeYari]

was I supposed to switch any thing with the plug/wires?
No.

Just a thought. Did you count off the cylinder position correctly? Standing in front of car, looking at the engine, cylinder 1 -> 4 from left to right. I'm sure you got it right but need to be sure.

[la_scanner]

No.

Just a thought. Did you count off the cylinder position correctly? Standing in front of car, looking at the engine, cylinder 1 -> 4 from left to right. I'm sure you got it right but need to be sure.

That's a fair question, they were labeled, so no issue there. I had called the mechanic and asked how they came to the diagnosis they gave. He told me they first swapped coils and that it threw a different code and that they tested with a multimeter to confirm it was damaged. I knew this was BS because it gave me the same code when I swapped the coils. It gave me the same code when replacing the "damaged" coil. Still throws the code after installing new Denso spark plugs as well.

Something else I think is fair or would be fair is for me to take the car to Toyota, let them fix it and bill the mechanic who charged me for this diagnosis and for the trouble it has caused me.

[la_scanner]

It seems a can of mass air flow sensor cleaner has solved the problem.

[2goyaris]

Thanks for the post on the MAF sensor cleaning. I was chasing the same problem on my wife's 07 Yaris. The check engine light was coming on when she would accelerate quickly, like when merging onto the highway. With the same code P0302. I've already gone through replacing the original plugs at 120K, and the coils were replaced recently. That was with P0300 (Random/Multiple misfires)
I just cleaned the MAF sensor and changed the air filter today while I was at it, it needed it. I took it for a test drive to floor it a couple of times and no CEL.
Edit:
code came back after a couple of days after the MAF cleaning.
Replaced all 4 fuel injectors. Tried just replacing the #2 cylinder injector, but then got another P0301 code, so replaced the other 3 as well. This solved my problem, no CEL codes for weeks now.

[bairjo]

For what it's worth, i have had the same P0302 code on our 2009 rav4. I replaced the coil and that was not it. I didn't check the iridium plugs since they were only in for 30,000 miles and should last at least 60K. I decided to pull the plug out and the electrode was gone. In fact they were gone on all 4. I replaced all 4 plugs and the code never came back. Why did they burn up so soon you ask? Well, I think what I did when I installed them used the torque specs for the 2AZFE engine and not the 2ARFE engine. The 2AZFE calls for 14ftlb. and the 2ARFE calls for 18ftlb. My point here is, check your plugs again, even though they have not been installed very long. As for my RAV4, time will tell if they will hold up for 60K like they should. If any of you have any thoughts on why my plugs burned up prematurely, please add them here.

[IndestructibleYaris]

Unless you do your own thorough diagnostics, I can't comment on another mechanic. Resistor type spark plugs were implemented after the dawn of electronic ignition around the 1990's. These resistors can go bad inside the spark plug leading to an open circuit that destroys the ignition coil. Your car could also be running horrible, thus destroying a good spark plug. Most mechanics are taught the wasteful technique of replacing systems rather than the individual component that has gone faulty among the group of otherwise perfect parts. This is done because most people do not understand diagnostics or the value of knowing the truth, and the experience of learning that comes with knowing the diagnostic truth.

You will never know the quality of a mechanic until you're more skilled than the man you're judging. Otherwise, you are just guessing. He knows tricks to diagnostics that you've never considered.

[IndestructibleYaris]

If you've removed the coils, then you're capable of diagnosing the spark plugs. The engine can run with the spark plug removed and the injector unplugged. Try a cylinder drop test with each component, and look and test the spark plugs. It's criminal to take the coils out and not take the spark plugs out for inspection