Pinging - tune problem?

**Jglisson** · 11-18-2007, 05:36 AM

I have a 99 T/A with basic mods (flowmaster, K&N cold air, mild tune - egr/air off, fan speeds, a little touch here and there).

Now that the cool weather has arrived I have a horrible ping under heavy throttle. Sounds pretty bad. I first suspected that I had a bad tank of fuel so I waited out on the tank and re-filled with good premium and it is still pinging. The car has been well maintained. Recent plugs (NGK TR55), injection cleaning, fuel filter.

Fuel pressure at the rail is 52psi with ignition on and 62psi running. I unplugged the MAF and the pinging has been reduced a little bit, but not much. Any ideas?

**Dial In GTO** · 11-19-2007, 09:26 AM

HI,

I would do a fuel pressure check under load.
I use a 3 foot long hose and gauge set up(taped to the windshield)
and go for a drive. The fuel pressure at full throttle
should maintain(around 58 psi) and not drop off.
If the pump and or filter are not keeping up,
the pressure will drop quickly under full throttle conditions.
If that test is aok then I would want to data log and evaluate.

Gary