p0300 code
 

i know theirs alot of articles to this and im sorry to post another but ive had this come on every so often since 60,000 miles. i now have 105,000 miles on her and it still runs great. no rough idle, or anything like the head problem. i was wondering if these h3's had injector problems or bad coils. mine is an 07. if it does is their anyway i can diagnose it myself. i dont like bringing my vehicles to the dealer. ive only had one problem with this h3 and it was wheel bearings. i would like to just figure out this stupid code. thanks

Basically, it's the knock sensors detecting slight spark knock due to low grade gasoline or an unusual load condition on the engine. This can be fixed by getting a custom PCM tune( like PCM for less) I personally don't like the handheld programmers much, although they have made some advancements in the last few years. Other causes could be old spark plugs(have you changed them yet?) or a loose plug wire causing an inter
Intermitent problem. Bottom line not really a huge deal uless you can hear a lot of detonation from the engine under load or notice an obvious misfire.

Random misfire. If you have been using cheap fuel, switch to top tier.

1) at 105K miles I would change plugs unless it was already done, AND use ONLY OEM ACDelco replacement plugs;
2) check all the wires to the coil on plug packs;
3) make sure you do not have an intake leak, check the 1/2" hose off the bottom back of the resonator box of the intake (assuming stock system).

If it persists, have it scanned with a tech II and watch what the 02 sensors are doing, you could have one that is slow or bad.

OBD-II Trouble Code: P0300 Random/Multiple Cylinder Misfire Detected

Note: I5 Atlas motors do not use EGR, but you can check the EVAP lines at the top of the TB to the canister and the line from there to the motor.

He has an 07, no handheld programmers available (unless somebody just came out with one?).

thanks alot guys i work out of town or i would of been able to reply sooner. yes i do all my maintenance when its soppose to be but that thing was driving me nuts and i hate putting that on here cuz everyone talks about that code but i knew it wasent the head. ill start doing somethings and looking around and hopefully i find it. ill post back when i do.