Recently i started the car and it was shaking more that usual. the CEL light came stating P0300 with random misfires. It sounds and feels like misfires so i believe this is true. I cleaned the MAF sensor with carb cleaner and the CEL turned off, however, the problem persists. I have not had the fuel pressure checked because it can be expensive with no guarantee. I plan on calling the dealer to see if it is in warranty. Any suggestions? The car is a 2007 with about 40K miles logged. I recently changed the oil and air filter if that matters. Thanks!
You used carb cleaner on the MAF? Rather than MAF sensor cleaner? MAFs don't like carb cleaner. How many quarts of oil did you add? How high is the level on the dipstick?
i used to get weird vsc messages in hard turns (voltage drop in sensors) and misfires when my 12v was dying. it then turned into a failing ignition coil (toppers to the spark plugs) that cost me about 80 bucks. i had a cylinder no longer firing. the car didn't pick it up but it was obvious to me... reduced power and mpg.. higher revs.. etc... the only way i was able to found out for sure was by listening carefully then pulling the coils out 1 by 1... you can't un-clip them (brown clip?) and you can't pull more than two or else the car will turn off. only pull strait up (after removing the bolts that hold them down) but... i think your problem is probably more 12v than coils... unless you replaced the 12v recently... in that case it would possibly be one of your coils (possibly)
I added 3.5 quarts of 5W-30 with no pre-filling the filter. yesterday, i opened my throttle body and noticed a little oil so i took out about .5 quarts but it did not fix the problem.
For future users, i think i figured it out. I used a Carb and air cleaner to spray the throttle body. there was a small amount of build up around the rim of the throttle body plate which i believe was allowing a small amount of air to leak into the engine. i have driven my car numerous time since and it seems to work fine.
Just had the same symptoms and codes. Ramdom misfire P0300, and P0302, P0303, P0304. Mine turned out to be a dead ignitor. Lifting the ignitors over an inch out of their sockets with the engine running revealed a silent ignitor between it's cracking bretheren.
Well, i am still having that problem but i am going to check out my coil asap. i will post the results. THANKS!!!!
When i lifted the coils (one at a time), all four would ping or crackle for a second then stop and the engine appeared to run smooth. when placing them back in, it would crackle again. Basically, they all sounded the exact same as i removed them. Does that mean they are all good?
having the same issue... i replaced coils, injectors and plugs and had misfires, #4 injector connector wouldn't snap in, so now no more #4 misfires. Just 1-3 randomly and I was looking for any additional fixes others might have done. As of this morning, I think i hear a vacuum leak not definitely on turn off and certain times giving gave or idling down to off so... gonna investigate right now just wish i had some dish soap and water with a spray bottle but.. i think don't think thatll work to find vacuum since its sucking..
