So I had a misfire in cylinder 3, i put a new plug in it and it' still shooting the code after I reset it. It has power but the car sounds rough and is hesitant to start. The shop said the coil was good but I haven't swapped coils yet to make sure that's not what it is.

The car had HKS M40XL plugs and i put NGK laser iridium in it and it already burned the electrode in 3 after 1500 miles so i ordered the HKS race plugs just waiting for them to get here. I know the car was burning hot thats why the plug burnt up. Even though i swapped in a new plug and the misfire is still there What could this be? Im blown away by it.

I have 2011 Evo X MR
tuned
3 inch intercooler with aluminum piping
bushur downpipe
borla exhaust
air intake

 

Misfire could be a few things. I'd start by first swapping the coil pack with another cylinder to see if the misfire comes with it, then do the same thing with an injector. If its one of those two things, its a simple fix.

 

I am leaning toward injector. I swapped coils and it didn't follow it.

 

Let us know when you swap the injector. I'm interested to see if that's the cause.

 

The shop did a compression test today, cylinder 3 was on getting 35. They traced the leak to the exhaust valve. The exhaust valves in cylinder 3 are bad and going to need replaced. Their going to replace the valves then check to see if the pistons and everything else is okay and re-machine the head.

 

Well that sucks a fat one. I wonder what caused it. Did they give you a quote yet?

 

So when the last owner had it he tuned it without the cats, well the dealership put them back on. I was unaware of that so that' what caused it. Luckily the warranty I got with the dealership everything is covered on the car up to 36000 miles. Seeing I've only put 5000 on it, all I have to pay is a $100 deductible. So if the pistons are damaged and I need a new engine block, I got lucky as bad as it is. Still sucks I don't have my car.