newbie question ...

I usually have the radio turned up pretty loud, so I don't hear many of the engine noises. Every so often I like to turn down the radio and listen to the exhaust note. Today, in between CDs I noticed that the engine was making an irregular low-volume knocking sound. The noise sounded alot like piston slap (frequency) but at a much lower volume and pitch (more like a thud). Oil pressure, temp were fine. I filled up at a different station than usual over the weekend. Did I get ahold of some bad gas(I'm sure it was marked 91)? The knock is very noticeable and I'm getting worried. What exactly does bad gas sound like?? Any help you folks can provide would be much appreciated.

 

With out hearing it I relly can't say... but are you sure it is not your injectors? they make a knocking noise some people confuse it as something wrong with the engine but it is normal.

 

Sue the gas station.

Try puttin 93 in the car next time.

 

all gas is the same......meaning if you get gas at mobil, or texaco etc. its all the same.......i would definetily put in the highest octane available in your area......i dont think 91 quite cuts it......i use 93 in mine, i think thats pretty much the norm , you might be able to find 94

 

all gas is NOT the same. I have a friend that works at Chevron. and he says it is in the way it is refined and what additives they use in the gas.... Some gas companys use additives to keep the injectors clean. sometime this can reduce the quality of gas you are getting.

 

Bad Gas??? I was gonna suggest this - gasrelief

Seriously, the ping from bad gas is a fairly high pitch, definitely more of a tinkle than a thud. Maybe you've got something coming loose, possibly an exhaust hitting bodywork, or it coiuld be a misfire, though you should get a SES from that.

 

well i have a friend that owns mobil and hes says that is crap!

 

 

thanks for all the replies. 91 is as good as you can get in So Cal. I put in some octane boost (at half tank) and topped her off at my usual gas station w/ 91 on Sat. After a few miles, I could barely hear the noise. It didn't completely go away, but at least my car wasn't sounding like a diesel anymore. Anyways I ran the car hard that night and I didn't see any performance loss or trip any warning lights(see Track Kill Stories). Maybe it's a combination of miles (4.6k now) and ****ty gas? Thanks for the help.

 

Have you changed the oil yet?

And Chevron gets the same gas that others do. In Florida gas stations sometimes get a tanker that has the brand name on them (Chevron, Exxon, Shell,...) but if you notice, sometimes they'll also get deliveries from Keenan,... They go from Chevron to Citgo to Speedway to ... Some brands come from different suppliers, but the same gas you find at Chevron or Shell or Exxon, you'll find elsewhere with a different name.

And you can go to a station with crappy tanks and get bad gas no matter what brand it is.