engine sound
 

Hello, i have a 2007 mazda 3s and over the past 2 months my engine light has gone on ranomly and stayed that way for about 1-2 days then it would go off for another 3 weeks then it would go back on. Then it stoppped about a month ago and it hasnt gone on since, but i did notice that the engine was making a slight humming sound that i never heard before and i asked the dealer and he said it was "a new fuel pump assembly in the 07 models" and that i shouldnt be worried. I have also noticed more vibrations when the car is idling. you dont notice them unless u are looking for them but it was runnign smooth as could be before all this engine light nonsense. So my question, shoudl i be concerned or is it running a little rougher becuase of the temp change that has takin place recently?

RE: engine sound
 

Hard to say, but it could just be different fuel. Winter mix as it's known. More ethanol in the mix to absorb moisture/condensation in the fuel tank. "We" used to call it dry gas.

RE: engine sound
 

so is anyone elses car running a little bit rougher as well with the cold weather finally here?

RE: engine sound
 

I just posted a similar problem.
My engine light has been coming on periodically.
Also idle is super rough around town, I live in Palo Alto and there is a stop sign every block for miles so the idle problem is getting on my nerves.

2007 Mazda 3s 30KMILES YIKES!

RE: engine sound
 

my car can run a little rough at the start. but after like 2 mins of driving.. she is as perfect as can be

RE: engine sound
 

My car is running smoothly. Now that it's winter, my MPG is down a bit, but no issues with roughidle.

I have hadmy CEL come on twice, which I have attributed to my M3 being overly fussy about the gas cap (both times, it has happened shortly after filling the tank). A simple disconnect/reconnect of the battery has reset it without complications.

My suggestions ....1) Buy a tank or 2 of gas from a different station. Rough idle can be due to poor quality gasoline, maybe your usual station has gotten some lousy product.2) Spring an extra couple bucks, and buy high octane gas (91 octane). 3) Finally, buy a container of HEET (water remover), and put it in your tank at your next fill up. You might have some water in your tank, which can build up over the summer/fall, but not cause problems until winter arrives.

RE: engine sound
 

i have almost exclusively used 89 octane since i purchased the vehicle last april so i assumed that it wouldnt be caused by bad gas. Thank you very much for your suggestions urbanman i will try them out and report back

RE: engine sound
 

i have a 07 I touring since January 2007. I started hearing these sounds about a month ago. Same sound you get if you were to have the heater/conditioner on, but its not. i wonder wat that is. anyone know?