I was cruising down the highway the other day in 5th gear at about 2800 RPM's. Usually if I am going to stand on the gas I sort of roll into it. The car seems to pull as good at half throttle as it does when its floored, I mean it will get full boost with the throttle about half way down.

Anyway I decided to just stuff it to the floor at 2800. There was a little bit of lag, then it started to build boost and start pulling. All of a sudden it felt like the car just let up and stumbled?

I had the radio on so I killed that and tried it again, if I roll the throtle on slowly it seems to be okay but if I floor it quickly it seems to build boost and then will stutter and stumble?

I'm thinking I might have a load of crap gas so I added a bottle of fuel system treatment to it.

I did a search and it seems that a lot of people that have had the P0300 code have experienced the same symptoms.

I'm just hoping it never does it again.

Pretty common or just crap gas maybe?

 

Never.

 

never for me either w/ two evos what are your mods?

 

Like 2 times, sorta, check the intercooler hoses...

 

Pretty much stock, running an APS cold air intake (no problems since I installled it), a Greddy Ti catback and the Mitsu ground wire kit.

When it did it I think I heard the engine ping (detonation) and saw a small puff of smoke out the rear view mirror. The sun was behind me so it made it easy to see the puff of smoke.

I put in a bottle of octane booster this morning and the car seems to run good, I haven't tried "stuffing it" like I did before. If you just roll the throttle on it seems to be fine.

Just wondering,

Thanks for the feedback

 

hmm it hapepned to me once but that was when i first resetted my ECU...

 

i THINK i know what ur talking about, its probably a leak to tell u the truth, is it like a loud sputtering noise? if it is, then its a leak, my stock clamps on my IC arent doing it for me so if i floor it in 5th, after a few seconds, i hear loud sputtering. its either BOV or IC pipes leaking

 

I had that prob when I first got my 03 evo and it turned out there was a crack in the cylinder head and coolant were getting into the first spark plug hole which caused mis-fires. I doubt you are having the same problem as me but you can check to see.

 

Maybe a fuel/boost cut?

 

WOW . . . nice avatar! Went into vapor lock there. This has only happened twice on the same tank of gas.

I haven't tried to make it do it again (by just flooring it in high gear from 2800) because it seemed like it misfire and maybe some pinging (detonation). It won't do it all if you just roll onto the throttle a hair slower.

The car is not using a drop of coolant but that would suck if it was a cylinder head leak.

Thanks for the info!

 

How many miles on the car? Might have a sticky fuel injector. That would be a reason for running thin enough to ping. What octane is the fuel?

 

It might just be you BOV?!

 

If you stomp on the gas and the throttle opens up and the air flows in but not enough fuel come through the injector, you will go thin and ping.
If you stomp on the gas and the throttle opens but the airway or filter is clogged and you get a glut of fuel, you will lag and get a puff of smoke.
Check your airfilter.

 

theres a good possibility of having a PO300 code if your car stumbles when cruising 80mph....

 

Check upper intercooler hoses!!!