rm09

Hey everyone,
I drive a 2002 GT all stock except for flowmaster mufflers.
Just recently i've noticed a ping/pop while warming up my car. It only happens about every 20 seconds. Then goes away once the car is warm.
Its loudest on the drivers side, can't tell if its coming from the motor or exhaust.
I've been told that its the exhaust pinging from the metal warming up.
Any ideas ??? it never used to do this before.
thanks

fidelcastrol

I get this too, I started running 89 octane and it went away.

hot sauce

running anything over 87 on a stock tune car is a waste of cash. the pipes could warm up and expand and make sounds til its warmed up. if your car is running fine i wouldnt worry

cliffyk

Not necessarily, many engines will ping on regular as they age and deposits build-up in the combustion chamber--this is not at all unusual, and finding that the next grade "up" of fuel quiets it is not unusual either.

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As to the OP's issue it could well be the noise he is hearing is caused by the down pipe heating and expanding. I have heard the heat shields on catalytic converters make metallic pingy/poppy sorts of noises as well; often if one or more of the spot welds holding them on breaks...

rm09

Ok, good to know. I'll try running 89 next tank. Thanks for the replies!

cliffyk

I don't think the noises you are hearing are fuel grade related in any way. Octane related "noises" typically occur on warm/hot engines, under load; and almost never (really, really almost never)) on cold engines while idling/light load.

As you described the noise and the circumstances of of its occurrence I'd go with thermal/mechanical causation...

rm09

ok, thanks cliffyk i'll try to check the heat shields on the cats maybe. I guess its not a big deal, it just bugs me when i don't know whats causing the noise.