Dreded P304 Misfire code

[ecko04]

@Flaniganskywalker sending emails to KIA does nothing but arouse suspicion, which it sounds like you’d like to avoid.

Also, no amount of email correspondence with KIA, regardless of what they tell you, is going to overrule the legal language in the powertrain warranty. The warranty language is specific enough to say that no individual can modify the terms and conditions of the warranty.

It is pretty standard with boosted applications that you’ll have to change the spark plugs more frequently than with a NA application.

The standard maintenance schedule is that the plugs should be changed @ 42K. But that’s in optimal conditions. If you’re in stop and go traffic or experience real summer temperatures, that interval is more than halved. Add a “tune” and that severe interval is further reduced.

If you’re making it through a year on plugs, then that’s money well spent. It’s better to go ahead and replace them before you start experiencing misfires and other issues. It’s routine preventative maintenance.

 

[Regs120]

Unforuntely it's hard to find a local garage in NJ that does not charge you 3 hours of labor which is ridiculous. I have to drive a fair distance to get them replaced.

 

[ecko04]

Unforuntely it's hard to find a local garage in NJ that does not charge you 3 hours of labor which is ridiculous. I have to drive a fair distance to get them replaced.

Even more of a reason to buy the necessary tools and do it yourself. You don’t have to remove the manifold to get it done.

 

[Spaceme17]

Unforuntely it's hard to find a local garage in NJ that does not charge you 3 hours of labor which is ridiculous. I have to drive a fair distance to get them replaced.

All you need is a spark plug socket, a long 12 inch extension, a couple of 10 mm sockets, and of course a ratchet. They even sell at Autozone, Oreilly's, a little tool kit with an array of just different 10 mm sockets as this is such a common size now.

The first time you remove the intake will take the longest, but it is very easy to do even taking your time not to mess anything up.

 

[CoconutRob]

I am just going to have a local shop do them for 120 bucks. By the time I buy the tools and aggravation of maybe removing the manifold its worth it. I now know for me to run my car like this I am going to have to accept that the plugs will blow out every year or two. Not exactly thrilling but it's the price we have to pay for performance/sports cars.

I guess I could get the backend flash but then that will defeat the purpose of a piggy back and might as well go full tork tune since it will void the warranty for sure.

TBH I am a little turned off by the whole mod scene now with this car. The market sucks for it and ECU is a PITA to crack. Spark plugs is one thing, but then what? Coils and fuel injectors? Gaskets? Ugh.

All you need is a few swivel sockets, do not have to remove anything except coil packs and plugs. With nervousness the first time took me about 1 hr maybe a little more. To do it again would be about 30min not that bad. Dont give up, you can do it.

 

[CoconutRob]

I just want a little more pep.I will visit pressertech--the money is no problem--i just do not want reliability problems.The most tuned car i ever had was a stage 2 eclipse--a 2008.It was in the shop at least every 2 to 3 months for issues--fuel rails--sensors--misfires.When it ran it was fantastic--but I literally would almost flinch when I started the car--wondering if the check engine light would pop up--cut power and another trip to the dealer.honda got 40 HP out of my Crosstour and all it had was an ECU tune and exhaust--on the computer box was an R--tune--then again honda did it.They even got this on stock plugs and it kept the warranty>But mitsubishi did my eclipse.The stinger is prob in the middle of these 2 companies.I have learned one thing--you start getting problems with mods like this--it usually keeps going.I have seen some of the videos but definite answers are hard to come by.I have 2 guys on this forum that had pressertech--have had no problems--they seem honest and claim the car is faster--but neither had a dyno to see what the gains were.My Cosrstour also had a bigger oil cooler and bigger tranny cooler--it also had the euro spec Type R rotors and cross drilled discs--but those mods really did not add any power.

That's why I like JB4 I dont always want to race around little pep map1, stock pep map0, and map1 is enough for me max.

 

[Luc343]

I'm curious what Kia have to say about an ecu tune...

Many years ago I owned a Hyundai and they were OK with certain mods, like exhausts, cai's but ecu tunes were out. They actually were happy to know that people enjoyed modding their cars.

It would be interesting to know whats OK by the manufacturer today?

 

[Regs120]

They encrypted the ECU to make it flash tunes damn near impossible. Damn bastards.

 

[Regs120]

Ok - updated the chipset after getting it in the mail (thank you for the speed). I went light about 4.5RPM or a little more and heard and felt the power cut out. There was fluttering in the intakes which worried me enough not to stress it passed that point. No check engine light but it feels like it is cutting the power. MPG is suffering under map 2 which is likely a clear case the sparks are not hot enough anymore.

Set back to Map 0 and when I get the spark plugs done Wednesday it should be cleared up. I am going to use Denso IKH24's . Is the recommended gap still .022 for those?

 

[Regs120]

Spark plugs replaced. Back up and running for another year.

 

[DevLF]

Just chiming in to say I wouldn't consider misfire caused by spark plugs with 15k+ miles on a tuned car necessarily a "failure". Its a maintenance interval. All cars have them. Its quite a common occurrence on ANY platform that you're going to tune. Your previous examples hardly have any relation considering you were using dealer provided tunes which are going to be much more moderate than anything you're going to find aftermarket.