Well i have been having some trouble with my evo for the past couple of weeks. I had my evo diagnosed at auto zone and at the Mitsubishi dealership, it had an o2 sensor problem and a cylinder #4 has been misfiring. I have noticed that when i turn my car on in the morning, it has a little trouble starting up and makes weird noises and when it is on, it idles at 2k rpm for a couple minutes and makes some weird noises as well(My friend says that it is just because of the extreme cold). I changed the spark plugs and the problem is still there. I have 272 cams and cam gears.

I am only 17 and i cant afford to be dishing out all this money at the dealership when they don't even know what the real problem is. If anyone has any suggestions as to what i can do i would greatly appreciate it.

 

damn. i thought it would be the spark plugs.

 

do you have any other mods that might be throwing off your o2? not sure why you would have a misfire. Is it just when the car is cold or all the time?

 

How old is the car? How many miles? Where are the weird noises coming from? Does it accelerate normally?

So many things go into a diagnosis that as much information as you can provide may still not be enough. For example, a bad plug wire could cause a misfire but it doesn't explain some of the other symptoms.

FYI - are you throwing any codes? If you don't know, you can go to your local autoparts store and, usually, borrow a code reader.

 

The car is a 2003 evo 8. 43k miles. The noises are coming from the engine almost a ticking matter. It accelerates normally until the rpms are really high, then i can feel the misfiring.

Mods are stainless o2 housing, three inch turbo back exhaust, injen intake and intercooler piping, HKS 272 cams, cam gears, arp studs, 255 lph fuel pump, custom tune, EXEDY twin disc clutch, stainless braided clutch line, swift lowering springs, drilled and slotted rotors, axis pads.

codes are P0304

 

buy a car you can afford to fix

 

When were the cams installed? Did you bleed out the lifters? One may be collapsed

 

Why do you gotta be a dick? I said i cant afford to keep bringing it back to the dealership. I can afford to fix it, but i cant spend 200$ for them just to change the spark plugs(which is how much they wanted) when i can do it myself. Each visit to the dealership is almost 100$ just for them to inspect it. So i am politely asking if anyone knows how to help me.

 

your driving a modded evo, what happens if the block goes and you need $5k to fix it? if your complaining over $100 then i doubt you could afford it


if its misfire its either spark or fuel, you said you changed your spark plugs so its probably fuel. check your fuel pressure and injectors. also check your timing adjustment on your cam gears, they may have slipped

 

Well, I've read that 03s have misfire issues. I have an 04 and have not looked into this issue. Maybe You should if you have not already.

What kind of 02 troubles are you having? are you throwing a code? Is it going lean? or is it going Rich? what code was it?

How do you know you are miss firing on #4 cylinder? Did it throw a code? Did that code come back after you replaced the plugs? Do you have any way to check codes?

did you try and switch coils to a different plug to see if the miss fire moved with it?

you could let it idle and hold a small propane tank near the intake manifold, if the engine rpm changes then you have a intake manifold leak....with out seeing the vehicle, I'm leaning towards this one.

Richard

 

i have a similar prob.
1.It could be your CUSTOM tune.
2. Spark plugs

check into them.

 

Sometimes this code is transmission related . There is a dealer TSB on this.PO 304 code.

Originally Posted by vonserb
I just took my car in to get fixed for the same engine code. The problem was the input shaft from the transmission to the engine. Mitsu issued a TSB to fix this problem and it was free of charge, its powertrain warranty too, so that 60k miles. Apparantly the old shaft wasnt designed right and was causing vibrations and whatnot to trip the error code.

I would definitely look into the input shaft problem.

Could also be the injectors...

What are the plugs gaped to? Gap them to .024 on a feeler gage

 

24 what...24 Bananas?

 

Uh .024 on a plug gapping tool or feeler gauges if you have them.

Ill bet you have a dead lifter though try to in car bleeding proceedure as noted in the factor service manual. Basically slowly bringing the car to 3000 rpm, holding it there for 10 seconds and repeat

 

Shot in the dark. How cold is it? Is there a chance your gap is too large on the plugs? When it gets cold here my car breaks up a little in th upper RPM's, mostly because the air is more dense, and the boost goes up 2 psi. When its warmer, I don't have any issues. I know I need to reduce my gap to fix the breakup in the upper RPM's. I am not throwing any codes.