I've been getting 2 CEL's indicating "cylinder misfire" for the last 2,000 miles. The CEL just came on during normal driving, and I've never driven the car hard at all. Should I concern about my spark plugs? I'm planning to bring it to the dealer, but I don't want them to blame on the mods I have.

 

I would talk to David at WORKS first, since this could likely be related to something with your flashed ECU.

 

Hmm I am thinking the HKS RS might have been the cause,
because I got cel once after installing the HKS RS. If anything switch back to stock intake and see if u will get CEL again.
Because the RS really messes up the A/F in the mid range, its really better to just run the stock air box.

 

A lot of Evos with RS has dynograph showing running lean
maybe that causes misfire code ?

 

was the flash done after the RS install? It is has bee nproven that the Smoothen flow of these intakes drasticly affect air flow into the engine.

PS cylinder misfire is basicly knock or detination

 

didn't you take out your RS intake?

 

1QWKEVO,
Could you explain more? If cylindermisfire is just knock/det wouldn't the CEL be illuminated a lot more?

 

I think he's getting the same thing i get, which is a P0300 OBDII code which mean random/multiple misfires. It isn't knock or detination, it's a misfire. I haven't heard any causes or solutions for this yet, but just like IS2000, my cel came on while crusing at normal speeds. It only happens in fifth gear however.

 

I am having the same problems. I come to a red light while idle and then I get a cylinder 2 misfire code. Happened twice to me so for and Mitsubishi has a case number opened up on my car.

 

Hi,

Doesn't misfire indicate that the plug did not "fire" as opposed to ping or detonation which would be uncontrolled or premature cylinder firing? I asked about it back when I had my Sentra SE-R and per suggestion someone had me remove a plug wire. Now I know what misfire feels like, heh. I also would get misfire in my Integra GSR when I had N20 and my plugs were gapped too wide.

Did you check your plugs? Were they fouled? How was the gap?

Good luck,

FB

 

OBDII Misfire codes are very sensitive and easy to set, hence the reason a lot of people get them.
For the HKS RS, most are probably experiencing a lean misfire. The conditions in the cylinder are lean and the plug misfires.
Misfire can be a weak fire causing a loss in engine speed that is seen at the cam and/or crank sensor, thereby setting off the code. Misfire is really any time the plug does not fire as expected as viewed by the ECU via the cam and cranksensor. It doesn't actually know whether the plug fired or not. So detonation can cause it also since it is a misfire or an early ignition that negatively impacts the rotation speed of the engine.

This is all from experience, I don't know exactly how Mitsu ECU determines a misfire but that is the common method. Remeber, the spark that jumps the gap only does so because the coil is able to overcome the conditions of the wire, plug and cylinder conditions. If the cylinder pressure is high (boost) and the cylinder is too lean the coil cannot overcome the condition and will misfire. Coil output is determined by the above conditions., it does not just fire the same each time.

 

thank you timz...

simple counts of dentination are normal, but when those counts become continuous or larger then alloud the ECu throws a code. Missfire is simplely a cylinder combusting when it shouldn't be, in most cases the plug stays hot from a lean mixture and combusts the fuel charge in the cylinder prematurely. This is also knowns as knock... For a cylinder to randomly throw an actual missfire from an actual ignition spark, especially on a new car, is a bit out of the ordinary.

 

I have a very nice through the mail reflash map for the HKS filter which runs really well That intake is very different than stock or any other and requires a custom tuned a/f map or it will cause serious detonation in the middle of your power band which may or may not be part of your problem

You are welcome to test out my reflash and if your problem does not go away I will refund you the entire 225 fee and flash you back to stock

 

Mine was misfiring really bad. I replaced the plugs and ran good as new. So I would suggest replacing the plugs first. It's fast, easy, & cheap. I've replaced mine twice now due to what turned out to be bad gas. I used NGK bpr7es, then bpr8es plugs. Got the plugs from NAPA (runs good). My .02

 

I have been having these same random Misfire codes(PO304) for a LONG while already. My coilpacks were replaced about 5000 miles ago, and my misfiring codes have gotten worst. I would clear the codes using an OBD2 code reader, AND/OR disconnecting the battery, and within a few minutes, no matter whether Im idling, driving hard, or cruising, the CEL light would come back on.

Btw, I have replaced my plugs also with the NGK copper bpr8es, and the problem still persist.

Ken