I need some possible info here!

My car is in the shop for a sudden development of pinging. Now the car only pings when it is in 5th gear, and only when I am trying to accelerate. Now I do not mean flooring it in 5th, because I know that will do it, but I mean even a slight acceleration = ping.

I first thought maybe bad fuel, so I filled the next tank with 89 from Shell. Still pinging. All my fluids were at the right level, and there was no mixing of the two. Now it has been pretty hot here in Sacramento recently, so I thought that may be helping to cause the problems.

The car has been in the shop since wed and they have not even touched the thing yet.
FWIW the only mods on the car are a K&N filter, LM1, and a Bassani Catted X. It is still running the stock tune.

Any ideas what may be causing this? My SES light has stayed off. Will the car throw error codes and not trigger the SES? I know the light works because it comes on when I turn the key, like all the other idiot lights do.

Just worried, and going through withdrawals!

 

What year?

How many miles?

How has it been driven?

Auto or manual transmission?

Does it burn any oil?

If it has been babied, has 75k+ miles, and burns a bit of oil then it's likely to be carbon buildup in the combustion chambers that has raised the compression ratio to where you'll need premium fuel (91 or 93 octane) in the heat of summer.

 

Sorry, shoulda included that info

Anyways, it is a 04 GT Manual. About 44k miles. It does not burn any oil, or leak oil. It does not get driven especially hard, but I do get on it from time to time. Maybe had it to the redline 3 times or so.

I am just trying to learn exactly what may be causing the pinging, and why the CPU is not compensating for it. Is pinging a lean or rich condition? I know this may involve a variety of things, like clogged injectors, clogging fuel filter, bad fuel pump, etc....

 

Pinging is associated with premature detonation in the cylinders. Usually caused by too low of octane, or lean a/f mix.

 

Yeah, but is he talking about pre-ignition or detonation? They're two different things. Detonation is when the mixture is ignited by the spark, but for one reason or another instead of having a controlled burn, it explodes violently. Pre-ignition is just when the mixture basically diesels and combusts from the compression alone.

 

Also pre-ignition is as the name implies, premature ignition of the mixture before the spark plug fires. It can be caused by too "hot" a plug, or a glowing deposit or sharp metal edge on the piston top or in the combustion chamber.

Sometimes improper cooling system operation can allow the engine to run hot enough to aggravate both of these problems.

In any event, the lack of any DTCs probably means that the AFR is OK so one of the first things to do would be to pull the spark plugs and see what they look like. Then while the plugs are out do a compression check to see if it's abnormally high.