dayglo

i understand that the knock sensor protects against pre-ignition but the causes on motorvate.com where "Engine knock can be caused by using lower octane gas than is recommended by the manufacturer, or by over advanced ignition timing. It can also be caused by a "hot spot" in the combustion chamber"
i run 92 octane always but im not sure if ive got a hot spot caused by red-hot accumulation of carbon in the combustion chamber.
motorvate doesnt say what causes of this are, or if they're simply just a normal thing and to have a knock sensor is the only way to deal with it.
besides having a good knock sensor i wonder how else i can prevent this from happening? is there some timing that should be set properly as well? ignition coils?
i wonder because once my car warms up it doesnt seem to drive as tightly as when its around the C mark. it still drives fine and enough power but with a small decrease in power and pull.

SkoorbMax

Our cars have knock sensors already, so you're covered there. Some cars that are speced at, say, 87 octane will find later in life that they knock unless they have a higher octane. This is the "hot spot", which is (I think) just crap like carbon deposits buggaring up the shape of the combustion chamber or heads. So these engines find that higher octane helps them.

In your case you're at 92. Our cars recommend 91, but with healthy knock sensors and a good engine they should not knock at 87. If yours is it's likely a caused by one of two things: bad ignition coils (very very possible), or possibly deposits, as mentioned above. I can't say from experience how well an engine cleaner will help it, but it's worth giving it a go. If that doesn't do it then new coils may help. Unfortunately these cost a few hundred bucks if you install them yourself (fortunately a very easy job - and I do mean EASY), so if a fuel additive or two will help you along that coulid be worth doing first.

Anybody else please chime in

As to whether it's normal to get a hot spot, I'm sure that it is over time. Even with the engine running as cleanly as possible with good fuel filters you'll still, eventually, have deposits you don't want. Have you used a fuel injector cleaner recently? You can get a cheap one like chevron's techron concentrate (pick up at walmart for around $6-7).

nateplaysbass

there's a short discusion about seafoam here at NWMaxima.com, it is in the middle of a long topic, but because of the search feature, the posts you want to read will have seafoam highlighted in red.Linky however, on this link they are saying that it doesn't do much for carbon buildup.

hope this helps
Nate

Jeff92se

iTrader: (82)

You really think those knuckle heads know anything?? hehe

Seafoam or the water injection method are both supposed to help clean carbon out of the combustion chamber.

nateplaysbass

I should link this to them, they'd come here and have a ball!

I better not.

Nate

njmaxseltd

iTrader: (19)

The knock sensor doesn't prevent engine knock and ping it only detects it and retards timing so you don't damage your engine.

You can prevent knock and ping by keeping your engine properly maintained and by running the correct grade of fuel.

Your maintanence should include your cooling system, lubrication, intake & fuel system, tune ups, exhaust system and correcting any maufunctions - check engine light warnings that might occur.

As long as you keep your engine properly maintained, it should not knock or ping.