Pinging when shifting? Maybe?

[blueapple]

I don't really know if this is a problem at all, but I have never noticed this in any other engines.

I have a 96 Camry with manual transmission

Say, I put the car in 4th gear, going 40mph ( any other RPM below 3K will do about the same, never had a chance to do high RPM, don't see why I need to )

Here's what I do:
I let go the gas and let the car cruise, or, say engine braking, then I press the gas in, if I do it quickly, not suddenly, just quickly (anything faster than easing in the pedal ), I can hear a brief moment of engine pinging noise ( or at least very similar ), for about 1/2 - 1 seconds. And this happens every time I shift, since... well... it's the same thing: let go the gas.. gas in...

I know that the fuel injection equiped or EFI cars will stop all injectors when throttle is let go, then resume when engine speed drops below certain RPM. But I can't duplicate the same noise by simply revving the engine. and I don't think pinging at all is a good sign.

I have a high Nox emission reading also.

What kind of symptoms do you get when fuel filter goes bad in a Gen3? I'm also getting slight rough idle, and somewhat low MPG, around 30 on highway.

THanks!

[Tommy]

A little birdy told me to get your EGR valve cleaned/fixed

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