Ping at 2200RPM -- Idle Mixture?
 

Hi guys,

Just lately my 89 Targa has started pinging at about 2200 RPM under light load, but only when at about 210F or above (needle at about 8:30). [list=1][*]I may just have a tank of bad gas. It seemed to start after a fill-up. I drained some out and put in some Octane +104 and topped up with 93 octane, but some ping remains, maybe less[*]A new wrench told me he adjusted the mixture last fall while doing a 45k service. I'm wondering if he leaned it out too much, and whether the idle mixture affects operation much at 2200 RPM? (The car never gets to 210F during the winter.)[/list=1]
The car has a Wong chip, but the chip has been in two years and this is the first pinging, so something is different.

Should I just run the tank almost dry and see what all fresh gas does, or is it worth cranking the mixture screw in 1/2 turn to see what happens?

Thanks,
RA

Beside bad gas it could be mixture, ignition timing or deposits in the combustion chamber. I would start with trying new gas (easy ) then checking the ignition timing and the mixture. Of course you should make sure the pinging you hear is indeed pinging/knocking and not something else.

At over $3.50 a gasllon for premium here it better not be bad gas.

Is it possible that the SW chip runs so rich that your cylinders are now loaded with so much carbon that might be causing the pre-ignition?

Joe

That's easy to find out. If you are that rich, it would show on your plugs.
I would 1) check the plugs for fouling, 2) get a full tank of fresh gas then 3) try the stock chip. If nothing turns up, look at timing, and other items suggested.

Maybe your plugs are getting old. That can be enough to cause pinging. When is the last time you had them changed?