Ignition Coil/Spark Plug

Hey all,

So I have had some misfiring happen on my 2017 taco 4wd offroad. I replaced all coils/plugs and all have worked except for the 5th cylinder. I went back and tried OM parts vs aftermarket cuz I have heard that toyotas can be finicky with aftermarket. Still caused misfirings. The only thing that seems to keep it firing is having the old plug/coil in there. It will still misfire every so often, but not like the new parts. Anyone else have any idea as to what is happening? I thought something with the wiring harness may be messed up, but it's odd that it works with just the old parts...therefore it wouldn't make sense as to the wiring harness. I am baffled.

 

Are you getting codes?

 

Can you return the new #5 plug and get a different one? If the old #5 plug is high mileage the new #5 plug could be defective is what I am leaning toward.

 

Yea, so I have tried different plugs and different coils too! Lol, so it's not defective new parts...

I think the head gasket needs to be replaced, as it has some troubles starting and after some research it sounds like there may be a small leak in the gasket. Though, that still doesn't explain why new parts don't work and old ones do. So bizarre.

 

Are you getting codes?

 

A: Do a compression test on the one cylinder..
B: Never ever buy aftermarket ign coils. A lot of garbage coming out of China. Don't have to buy from the dealer, but make sure you get a real Denso coil.

 

Yea, it is popping the code off for misfire on cylinder E (5). That's all the code is though.

 

P03 something? Not one of the P11 codes like P11F0?

 

Have a look at the engine failure thread. Not to scare you, but it's possibly a bad head/valve issue like many others. The ones under warranty, Toyota usually replaces the bad head.

You need to do more thorough diagnosis at this point. Need a compression test and/or a leak down test of cyl 5.