I have been told that NGK has cooler running spark plugs. I am wondering if this would help solve my pinging & overheating problem?

 

Why would your maxima be pinging and knocking? Are you using the recommended fuel? Even on regular, the knock sensor should compensate for detonation by adjusting the timing. If the knock sensor is the problem, then it does little good to go with different plugs. That's like treating the symptoms, but not eliminating the cause of the problem.

 

http://forums.maxima.org/showthread....threadid=45742

 

It's not just knocking, but when going up hills with the a/c on, it starts to overheat and knock. When shifting from 1st to 2nd (auto trans ) it knocks. I have put 91 octance gas in it since day one. How can I tell if the knock sensor is bad?

 

http://forums.maxima.org/showthread....threadid=45274

 

You treating the symtoms and not the cause. On a stock or near stock engine, the stock NGK platinums should be more than adequate. Your problem suggests that you should have a QUALIFIED mechanic w/ the proper diagnostic tools to determine the true cause.

Ie.. overheating due to a cooling/timing etc.. will cause the engine to run hotter, thus causing the engine to ping in situations that it wouldn't normally ping. Find out what is causing the overheating.

 

Cooler plugs will provide no benefit in your situation.

Pinging, also called engine knock, has a sound often described as an unpleasant irregular metallic rattle, similar to shaking a coffee can full of marbles. Pinging is pronounced when the engine is under load, such as climbing a hill or rapid acceleration.

Causes of pinging include:
- fuel AKI too low
- ignition timing too far advanced
- lean mixture
- carbon deposits in combustion chambers
- EGR valve stuck closed
- EGR passages obstructed with soot
- EGR vacuum signal hose(s) split, broken, or disconnected
- engine running too hot

There are other vehicle sounds which are similar to pinging. The most common example is an exhaust system heat shield which has become loose and rattles or buzzes, especially at certain engine RPMs.

 

Overheating may be caused by ...

- insufficient coolant ...
- external leak: radiator, heater core, hoses, water pump, thermostat housing
- internal leak: blown head gasket, cracked engine casting
- coolant does not circulate properly ...
- stuck thermostat (stuck closed, or unable to open fully)
- bad water pump (loose impeller, worn impeller vanes)
- bad radiator hoses (outside may look okay, but inside has collapsed)
- obstructed radiator ...
- external debris (road trash, insect bodies)
- internal deposits (corrosion, minerals from water, coolant additives)
- failed electric cooling fans
- bad temperature sensor (cooling fans don't turn on)
- air pockets (air trapped in cooling system)
- faulty radiator fill cap (unable to maintain pressure)


Less likely causes ...
- obstructed exhaust system
- improper ignition timing
- lean fuel mixture

 

You report pinging and overheating. It is possible these two symptoms arise from two different causes. However there might be a common cause. In addition to the check items mentioned in previous posts, please consider the possibility of an obstructed exhaust system, possibly the catalytic converter. Here are some diagnostic tips I found on the Web, along with the source of each.


From http://www.misterfixit.com/cat.htm

You can do a vacuum check at idle and then at 1500 RPM. If the vacuum is say 21 inches at idle and like 15 inches at 1500 then the cat is likely clogged.


From http://www.ghg.net/fastlaw/vacuum.html

Blipping engine speed ... Quick drop to zero then return to
normal reading indicates that the Muffler is clear.
Blipping engine speed ... Slow drop of pointer then slow return
to normal reading indicates that the Muffler is choked or blocked.


From http://www.turbotektoys.com/_TipsDisc/00000007.htm

Connect vacuum gauge, run car at 2500 RPM. If the converter is plugged, the vacuum will slowly drop. A one minute test is plenty of time.


From http://www.2carpros.com/topics/catcon.htm

To test for a plugged converter, drill a small hole in the exhaust pipe right before the catalytic converter. Install a temporary hose fitting and attach a long rubber hose and a 0 to 10 pound pressure gauge. With the gauge inside the car, drive up a hill or accelerate and read the pressure. Normal is 2 to 3 pounds, restricted 4 pounds or higher. The drawback to this method is the small hole will need to be welded shut after the test; a minor job if you have a welder.

 

I just recently took my car to a dealer and they checke dit out and said that they did not find any problems with the car. They did not want to mes with the timing. So now I have to do my own research to solve this problem