As in title, I only get this on cold starts. Once the car is warm It operates fine idle, partial throttle, even wot. It's only until car reaches operating temperature. This didn't start until I got my fic 1050 (brand new) , grimmspeed boost solenoid (brand new) , Walbro 255 (used) and a tune. Plugs have 1000 miles on them and coils have 25k. This is on my evo ix with 25k miles. Unknown cams from previous owner, tbe, custom intake, grimmspeed boost solenoid, fic 1050, Walbro 255, Tuned on a Mustang dyno at ~300whp. Didn't have this p0300 until after the installation of grimmspeed boost solenoid, fic 1050, Walbro 255, and tune.

Does it idle fine cold but first gear is misfiring while just cruising?

Always start with the easiest/cheapest fix plugs, wires, so on.

More info to clerify: 1000 miles on plugs. Only misfires in open loop it seems when cars cold. It does misfire in first only if I start driving while it's still cold/ in open loop which I basically never do. Might just disable code because car runs 100% when it's warm and I can't pass inspection. Any help/comments/suggestions appreciated. Remember p0300 random multiple cylinder misfires only code I have.

Using the proper plugs I assume. I had a very similar situation with my previous evo, Like damn near same thing. I know the car had a tune issue and fuel issue which ended up putting a hole in piston #4. I would be weary of driving the car until you figure out what it is for sure.

why do you have injectors if you're only making 300 wheel? stock injectors would have handled that fine

change back to stock injectors and fuel pump and see if it fixes the misfire

I'm not to worried since the car runs perfect 100% once warm and it didn't have this issue until after my tune and other mentioned parts installed . If it's in the tune I'm sure they'll figure it out when I go back in since they're Known good tuners who specialize in evos and I'm sure they ordered me the right plugs. What was the fueling problem you had? I'd like to check it out just in case.








Tuner suggested them. I should be making at least 320 I'm hoping after ets Intercooler kit, some aftermarket ( open to suggestions) internal waste gate and retune for 28 psi over my current 26. I also feel like it's better to not be running a high duty cycle all the time.

Thanks for all the replys.

Bump help with random cylinder misfire.

egr?

idk if we have the same problem but on cold start up it idles fine just wants to stalI if I wanna move it but once it at operating temps it fine.

I see your from mass were you from ?

Quincy

Ok so now I read and cleared the codes again and I got a cylinder 4 misfire. Pulled spark plugs all look relatively the same with the exception of cylinder 3 electrode being a little curved..? Anyways I had swapped the coils sides just in case and didn't change so should I be looking at a fueling issue? I think my fic 1050 might be the culprit.

Are the stock Evo ix plugs good for a bit over 300 whp or should I run colder plugs? Everything I find is on Evo viii spark plugs.

Here are pics of plugs after 1000 miles. Mod list on first post. My tuner said they are ikh24 plugs one step colder than stock.

Cylinder 1:

Cylinder 2:
Cylinder 3:
Cylinder 4:

Again I've gotten random multiple cylinder misfires mostly and once I got a cylinder 4 misfire. Any help is greatly appreciated.

I had a problem like this. It turned out that the head gasket was leaking a small amount of coolant into one cylinder. So if you parked over night there would be enough coolant in the cylinder to cause a misfire for a few seconds when starting up in the morning. I can only assume once the engine heated up the gasket began sealing again as I didn't have any issues with major coolant use or pushing coolant into the overflow.

I only realized what the problem was after pulling the head for another reason.