I can't find the cause to my misfire: please help
 

ok. i know there have been a bunch of threads on this but i can't seem to find the answer i need without someone telling me to 'buy the parts and find out' if that's what is wrong or not. i also read some random online mechanic's write-ups and such on this matter which helped me get to where i am now...so here goes: the car was misfiring right around powerband (roughly 3900rpm's) at a 25% throttle or higher. the strange thing was if you stayed very light on the throttle you could reach redline without any sign of misfire....i have no mechanical noise (by the way i removed my PB ECU before the issue since it was going crazy but Gabe at RRM took great care of me {thumbup} and i removed the header to sell it)...after some work i determined it was a 'lean misfire.' a friend and i pulled some codes and here's what we found:

P0141 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)

P0304 Cylinder 4 Misfire Detected

after a bunch of diagnostics i found that the O-ring on the high pressure fuel line (where the fuel rail/line bolt together) was damn near shredded. i literally had a puddle of fuel sitting on the runner of the IM. so i was left with a few options. i put a can of Gum-Out Injector Cleaner in the car incase there was a clogged injector, replaced the plugs, put my magnacore wires back on, removed fuel pump, cleaned fuel filter, replaced the O-ring, checked PCV, reset the ECU and checked for vacuum leaks. here is where things get interesting: ok...so now i start to think i may have solved the problem...started the car and there was a slight misfire at idle. if you open the throttle the slightest bit and raise the rpm to about 800 the misfire goes away. the high end, leaned out misfire was 95% solved by a $3 O-ring and some new plugs....only problem is now the car misfires around 1300-2700 rpms or so...can somebody please help? :dunno: the only other thing i can think of is a bad O2 sensor (i've had that code since i installed my RRM header and the CEL came on) or an EGR valve stuck open. any help is greatly appreciated. i would really like to get to the track again now that the weather is nice. thank you.

mark

Cylinder 4 is the one with a coil pack on it, right?
If so make sure your coil pack is good. I think autozone can check it. And if the coil pack is OK then buy that thing that connects the plug to the coil. It's only $15 at any Mitsu dealership. If that is not going to work put your stock wires back on and change plugs.

It should work!

thanks man i will definately look into that.

alright here's the deal. i took the car down to my exhaust guy (its a regular garage not a muffler shop)....so the other mechanic knows me and my car and hears the **** idle and tells me the obvious: "sounds like a misfire" he has me pop the hood and says he thinks he can fix it. tell me the boss wont be back for an hour so just pull the car around and don't tell anybody. i told him the codes i pulled, what i checked, etc and he immediately pulls out the coil pack + spark plug in 4. i was arcing like a mofo to sum it up...he showwed me how to diagnose arcing by reading the plug instead of the pack or wire and fixxed the car for free (gave me a new boot basicly)...thanks for the help {thumbup} you were right.

How will your plugs look like if you are arcing?

look at the top end of the plug...on the ceramic itself you'll notice a small brownish/black specs or hashes where the spark grounded improperly and burnt the ceramic. in some cases it will end up leaving a crack in a bad scenario. also, the mid-section of the plug (ive got a lack of name for this part) the area that your socket will match up too (above the threads, before the ceramic) ....look for any discoloration of the metal. that is also a sign of improper grounding.....thats some of the rules for plugs.....for coil packs look for a white (or brown) residue inside or around the boot. if you are having a problem post pics of your plugs and packs and some of the guys will help you read them.

im having i think misfiring going on at idle to low mid rpm my car sounds like a boxer engine....bah..bah...bah...bah...and when i put a timing light on it it skips beat its not a constant strobe....its a random strobe then off then strobe then off...i havent figured it out..this had happened after they had put the (california emissions) - recall on the ECU.... now the car runs like a dawg... i hate it so im trying a new ECU non flashed...will get back to you on this....idk but thats what im getting for a misfire....if anyone has ideas ther than the ones on here let me know and the ifo would probably be useful to everyone...

^First off, thanks for searching and using an existing thread! Second, you said this started after the dealership did their ECU reflash? then take it back and tell them they f'd up your car! Just a thought...

Another question If you are misfiring does it ALL the time trip a code or could you misfire with out the computer detecting it?!

Yes, you can misfire without a code being thrown.

not always the best of ideas haha. i got kicked out of a NJ dealership for calling a mechanic on a terrible mistake. the service manager got nasty when i did so and it got really heated. if you confront the dealership do so in an non accusing way.

most misfires DO NOT throw a code...especially on the lancer. however, if you know what you are looking for the dummy light and code are completely unnecessary. here are 2 useful links to help you diagnose and correct a misfire:

Plug Chart

Misfire Sticky (see post #27)

there is a lot more on the boards about misfire but those 2 should be pretty helpful {thumbup}

mark
:mitsu:

Yeah, don't the workers dumbasses! That's an easy way to get your @ss booted out!

:lol: i wish i knew that when i was 18 {thumbup}

misfire
 

When my car was misfireing we found the problem to be the coilpack stem ( the thing that conects the sparkplug to the coilpack... my Lancer has ben running pretty good to date yo... you might wanna go ahead and change your sparkplugs yo....

How much did that run you?