Motor pings, knock sensor computer code

[JWMAX]

I just posted this on the end of the last subject about EGR valves too. Help! I may have a possible EGR problem or something else. Please give me suggestions before I have to pay $80 for a shop to try to figure it out. My motor pings about every 3-5 seconds when it is at operating temperature and the knock sensor is going off and retarding the timing when I accelerate and very noticeable above 3000 rpm's and a little below that. The motor also pings for a while after the motor is turned off (until it cools down a bit). I don't know if this has anything to do with it either but when my car idles it sounds like George Jetson's hovercraft and is not very steady. When the motor is warm and I rev it up I can feel the valve moving up, or if I take off the vacuum hose I can feel it sucking when I rev up the motor. The car runs perfect before it warms up and has plenty of power all the way to the redline. Another part of the EGR system has a knob on it that looks like I can adjust it but I'm not sure what that's all about. It also has some plugs in it and stuff.

Just a little FYI: The car is a '92 Nissan Maxima SE w/ 130,000 miles. Replaced w/in last 3 months: spark plugs, air filter, fuel filter, knock sensor and harness, also cleaned out the fuel injection system and flushed the oil system with a cleaner called BG from a local shop. I was told all of the fuel injectors have been changed already but one of them does'nt look as new. The car burns no oil and runs great other than the hesitation. I use no less than 93 octane gas from various places with no improvement. The car has coil packs instead of wires and they dont seem to have any cracks in them. The timing is electronic and I haven't messed with it.

[JWMAX]

Sure wish someone would respond, I'm running out of options and I know there are a few mechanics that know what they are talking about. PLEASE HELP

[KC Ron Carter]

The key to ping or detonation on daily drivers with no other issues is 99% carbon buildup.

A 2000 mile road trip will clean it off or:

It is a manufacture provided service procedure to flash the combustion chamber with steam to force the carbon to break free from the piston face and valve face.

With the engine at normal operating temperature and approximately 2000 RPM, allow the engine to ingest by a vacuum hose 12 oz soda can of water.

A puff of steam and the carbon is gone.

Adding ChevRON TechRON will clean the back side or tulip of the valve
and all components on the fuel path, of varnish.

You can use as often as needed.

This is a must deal if you are near a pinging point and using forced induction.

Later,

[JWMAX]

Thanks for the response. I did the BG cleaner and they put some cleaner thru the intake and then put another cleaner into the gas tank and tell you to run it for a while. It helped a little with the power but it still hesitates and pings like normal. This is not a pinging under load though, like most places talk about. It is only when the car is warmed up and even pings after I turn the car off for a few minutes. My car is bone stock other than a K&N box filter.

[JWMAX]

Just wanted to update this thread to say that I found my problem. I tested the front three injectors with a multimeter and the center one was three times the resistance it should be. I replaced it and it still pings but I think it might be the exhaust pinging. Maybe a catalytic converter? It still idles funny but it runs much better.