I use 93 Octane (Shell or Amoco/BP)over here when I get the chance, but under heavy accleration, I can still detect some minor pinging. What could be the cause of that? Is it normal for a car with 90K miles? Is it weather related (90+ degrees and humid)?

 

I believe extreme weather (high heat), as well as say...torquing up a steep incline can increase the chances of pinging. Someone please correct me if I'm wrong.

You shouldn't be experiencing pinging at all, really, as long as the knock sensor is fully functional. The only way I understand it would allow pinging is if the KS was still operational, but it had deteriorated to the point where it was less sensitive than factory spec, thus not detecting the vibration in the block and not retarding your timing. It seems peoples problems with the KS usually go the other way around though, as in, timing getting retarded inappropriately. You could test the KS - you can find how to in past posts

 

Deposits that build up on the valves etc... can sometimes cause this. Have you run any fuel system cleaners through the car? A good one can help with this problem.

 

I might be wrong but in the owners manual *** says some periodic valve noice under hard acceleration means you engine is operating at peak efficiency.

 

I'll try some of that and see if I can come up with some codes for KS. There is a lot of fluff out there when it comes to those fuel injector system cleaners....do you have any recommendations?

Thanks for the replys...

 

This thread discusses BG products, which many people here have used effectively. It's very concentrated.
http://forums.maxima.org/showthread....ystem+cleaners

Others have used Redline Fuel System Cleaner amd of course Amsoil has products that do this as well, though honestly, I haven't come to an opinion on well it works yet. http://www.mdvsynthetics.com/guides/additives.htm#pi

 

I would also begin with a good fuel injection service. If you want it done right and quickly, go to a shop that performs the BG fuel injection service. They basically hook up a can of BG cleaner (VERY concentrated stuff, which is why it can only be hooked up at the fuel injectors, and not run through the gas tank), to the fuel rails, and run the engine off that stuff. It costs about $50 Canada here in Toronto.

If you want to do it yourself, I suggest using something called GM top engine cleaner. It is a foaming intake cleaner. You basically disconnect the intake track, fill the intake plenum with the stuff, and run the engine while shooting it in. This is best done on a warm engine (deposits are softer, the heat helps the cleaning action). With the engine nice and hot, disconnect the intake track, spray into the intake plenum, and let it sit for a while. Then start the engine, and inject this stuff into the intake with the engine running. This will definetly clean off the intake and the valves.

If that doesn't work, you may want to check the KS. Through my experience, components like the KS often perform well below design specifications long before they throw codes.

 

BG44K can be added to the gas tank. It's the cheapie way to do it, $15 vs. $125 to have it done.

 

If he's just gonna do an intank, it won't do nearly as much.

 

Very true, I just wanted to present different options depending on his budget.

 

$125 eh? Here in Toronto, my Volvo dealership will do a BG clean for a little over $50 Canadian.

 

A vacuum leak can cause pinging. Older Explorers are notorious for having leaking intake manifold gaskets that result in pinging under load. It is strange, though, that the knock sensor isn't taking care of it.

 

...I was like WTF..UNTIL...I tried REDLINE fuel injector cleaner and the engine has been pretty silent eversince. That Stuff really works.

 

Yah, I like the Redline SI-1 too. I use that, BG when I can get it, and AMSOIL.