Engine Ping
 

Our G37s (7AT) has intermittent engine pings when accelerates normally from low speed rolling (under 5mph) or from dead stop. The pings go away as soon as the throttle is eased off and wouldn't occur again when the acceleration resume immediately.

Car runs fine and the engine ping doesn't occur under any other condition.

We have tried different brands of premium fuel and also cleaned the MAF's. New air filters and oil also.

Any sound advises will be appreciated.

Are you sure it's not valve train noise? An OBD/CAN logger that can read the knock sensor variables will verify knocking or not.

it was engine pings as it was relatively loud and only occurred during acceleration from dead stop or rolling. There is no warning light or even pending code. My mechanic reviewed the fuel trims and said that it ran lean occasionally which could be the cause of the engine pings.

Engine is smooth and relatively quiet (compared to the Z) and the engine ping doesn't occur under other driving conditions.

Also ran through a few tankful of fuel additives (techron & lucas) and didn't help.

Maybe a lazy o2 is causing the lean condition?

Possibly, but I think it would eventually throw a code? Same for the knock sensors. There is not even a pending code.

You can run about 3 gallons of ethanol (the rest gas fill up) it won't hurt anything and the alcohol will clean things out and it's high in octane.

I personally know what your talking about as I've had this same issue with mine for some time.

At one time I reconnected the O2 sensor from the HFC's, and noticed on my daily morning commute where I would notice it the pinging stopped.

This went on for about 2 weeks but nonetheless it returned.

Im also thinking it has something to do with the O2 sensor intermittently working to cause the off idle lean condition.

I to got not cel and will when I get around to it replace the O2's to see it that will make it go away.

The runs fine but like you know it's just annoying to be pulling from a stop to be pinging like your driving off in the wrong gear.

This is my wife's car and it is also an 09 like yours. She said the same about being embarrassed getting that engine pings.

This problem started at about 55 to 60k miles and the car is completely stock.

bad/lazy O2 sensors (pre-cat) can certainly cause a lean condition, but why only occur under 'off idle' situation?

I hope you will find a solution.... ;)

I doubt it will be your o2 sensors (these cars probably don't even have o2 sensors they have laf sensors) they don't typically age like classic o2 sensors. If I'm wrong and it does use classic o2 sensors then it's even less likely as o2 sensors usually fail being stuck at a low voltage which tells the ECM the system is lean (when it truly isn't) and ends up adding fuel so it's actually running richer.

I would be curious as to have clean the backs of your valves are. Or what you knock sensor data is. Sounds like the system is bumping the timing really far.

vacuum leak will cause this also, lean condition with pull timing. I had this happen to me 09 also my it was my intake mani was leaking, re tightened it and it went away.

where was the leak on the manifold?

I would think that vacuum leak would effect the idling as well.

Not always. You would be amazed at how far modern cars can compensate now days. A big clue would be if you reset te ECM and ten it runs like crap. If the vacuum leak comes on slow and gets larger over time then the ECM can constantly compensate and in theory should throw a code for fuel trim out of spec but not always. A good example is vw 1.8t, they always crack at the PCV elbow and develop a leak yet no code and no obvious poor running. Disconnect the battery to work on something unrelated and next thing you know it won't run (starts and dies).

Back bolt at the manifold, the one near the fire wall.

we have reset the ECM and nothing really changed.

Other than the occasional engine pings during off idle, the car runs/idles fine.

did you have similar engine pings only under off idle condition?

How did you find the manifold leaks, smoke test?