Engine ping under light throttle

nis350

Need some expert advice about this issue. It is for our G37S with 7AT.

The car is totally normal at all time with the exception of occasional engine ping during take off from dead stop or slight rolling with light throttle. Car would start fine, idle and run smoothly otherwise.

We just have to let go the throttle for a second and everything would be back to normal. Engine ping never occur under any other situation. My guess is for some reason the fuel mixture become lean and cause the ping.

I have cleaned the MAF numerous times and run through a few fuel system cleaners already. Fresh air filters and oil etc. Car is totally stock.

TIA.

SouthArk370Z

Get an OBD scanner and see if the ECM has thrown a knock DTC. If not, then I'm guessing that you are hearing something loose in the engine compartment that is rattling around and not engine knock.

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nis350

No code from the scanner, not even pending. My mechanic did say that the fuel trim indicated lean condition and we have reset the ecu, but condition didn't go away.

It is a fairly fast clicking sound accompanied by a slight engine vibration. Everything's back to normal once you lift the throttle and re-accelerate fine subsequently.

DOOMMONKEY777

Stock tune? Any mods? Of yes and no, I had this bad MAP sensor on the top of the intake manifold, it made all kind of problems, including being lean then wet, then lean, basically change randomly under load.

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SouthArk370Z

If you're knocking, the ECM ought to see it and throw a DTC. So I'm still guessing you have some other problem besides knocking. But that's just a guess.

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barncobob

bad tank of gas, try another brand?

nis350

That's what I thought as well, expected to see the warning light on the dash as well as the code, but nothing. The pinging noise only occurs under the condition I described in the above post. The engine is very quiet and smooth otherwise. It is actually quieter than the Z which has less miles.

This has been going on for awhile and we have tried every single brand of gasoline available. The engine is stock.

As for the MAP sensor, can I clean it with MAF cleaner? Looks like it is held by just one screw?

DOOMMONKEY777

Remembering now, some one came to me with a low rpm engine knock, asked me what is wrong, as i remember the car was at idle and you can hear the valves ticking like a slight knock, then pass 1500rpm it goes away.

Solution, changed brand of oil used in the engine from Valvoline to Royal purple or Nissan Easter oil 5w-30.

The tick was gone, but in my opinion it does that on old oil.(filter is clogged and less oil travel through the engine during low rpm.)

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scope22

I had the same issue but i'm on Uprev and mechanic made knock sensor more sensitive and it went away, maybe you should try replacing it.

nis350

thought about the knock sensor, but the engine shouldn't ping under light throttle condition so the knock sensor shouldn't have to kick in to retard the timing.

furthermore, i think it should throw a code for bad knock sensor?

ANMVQ

Mine was doing this once, I had a intake manifold leak, try checking that?

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nis350

any tips on how? where was the leak on the intake manifold?

did it only occur under light throttle? I wonder if the vacuum leak from the intake manifold would result in leaner (more engine ping) condition under more load?

SouthArk370Z

The amount of air that leaks is dependent on the difference in pressure (delta P) between manifold and ambient. Delta P is lowest at WOT, so the least leakage occurs.

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YYZ

this

DOOMMONKEY777

Post a Video.......

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