TCReedy1

I have 28,000 well cared for miles, no short runs, always get car hot, always use either 93 or 94 octane gas. Over last 5000 miles or so, the engine has started "pinking" more and more upon light acceleration in any gear except 6th. Typical noise is a light metallic rattling from the engine which sounds like someone rapidly shaking a bean in a glass bottle (good description eh?).

Mazda dealer says it is "Pinking" and that i must make sure I use at least 91 octane gas. I told them I never use anything less than 93 octane, they just shrugged their shoulders and told me they could do a fuel additive to clean out the engine but i`d have to pay for it...

Any ideas out there?

Yours gratefully

Tom

alnielsen

iTrader: (4)

Hello Tom,
It sounds like you dealer was refering to Pinging. This is also called spark-knock and predetonation. This is caused by the gasoline exploding instead of burning in the combustion chamber. Higher octane fuels are used to prevent this. This is sometimes caused by carbon buildup and that is why he was talking about using a fuel additive to clean the carbon out of the engine. Taking it easy with the car and shifting the car a a very low RPM range could be a cause of carbon buildup all thou there are many possible causes for an engine to Ping.
I and others here have reported being able to use 87 octane fuel without any problems.
Good Luck.

Brice-RX8

If you got carbon build up then the best thing to do with this motor is run it hard to get it to blow out.

czr

iTrader: (3)

Try a different brand of higher octacte gasonline like shell. You may need to rev that baby up to 7.5k+ every now and then also.

zoom44

you could also have a faulty knock sensor. did they not do any checks of the car itself when you told them of this problem? and by "mazda told me..." you mean a service person or service writer?

TCReedy1

Thanks everyone....I regularly thrash the hell out of my engine, enjoying the sound of the little warning buzzer at red line. I drive the car as hard as I dare as often as possible. All of my runs get the engine well hot. I think if a knock sensor was malfunctioning then the OBDII would put up a service engine light. I just think it has some carbon build up and it needs an additive cleaner or a long freeway run for a couple of hundred miles may do it. When I refer to Mazda, i mean my local dealer technician whom i get to meet more often then I`d like...

Tom

mzdoggmann

Is the key here to longevity heavy on the Long Runs (& high Revs) and keep short distance/stop & go type to an absolute min.?? I know the short city type driving punishes any engine, but is it the kiss of death for a Rotary (for some of us urban dwellers, it may be unavoidable.)