I can finally make threads. I have been reading up on knock sensors and trying to read up and understand if i need to replace mine (mi. appx. 76,000). I know they do not throw codes, I know what to do to replace and i know KS detects engine knock and sends a voltage signal to the ECU, but what is an 'engine knock'? If no one wants to explain, link me to a website that can since I couldnt find one.

I know noobs question get flamed easy here, so hopefully I can get off light.

 

Engine knock is a pinging sound. Typically you may initially experience it when going up a steep hill and accelerating. It is more common to experience it in hot summer weather. I have had my car since day 1. My car only has 58,400 mostly highway miles on it and I have only experienced engine knock twice. Recently I experienced it on the freeway after I filled up in Washington state with Chevron 89 octane gas. I have no problem running 89 octane Canadian gas, but my car didn't like the Chevron 89. The engine knock has not reoccured since.

I also had a problem about 5 years ago going up a steep hill on the freeway in the summer time with the A/C on, 4 people and luggage in the car.

What makes you think you need a new knock sensor? At 76K, I doubt you require a new one.

 

Pre-ignition.

Also, KS does throw an 0304 code if its malfunctioning, but not always. The best way to test it is to get the multi-meter out and check for resistance.

 

What he said. Plus if you notice your burning an excessive amount of gas, and you havent been driving that much, check out your KS would be a good move. If you have noticed anyperformance change or anything then @76k you should be fine. But once again check it out with a multimeter to be sure.

 

Pre-ignition?

 

I think he meant pre-detination.

 

Good deal, thanks for the info. I was thinking I might need a replacement just because I heard about people replacing theirs and it was common. I just wanna check up on the basics before I start putting the parts in the car, I still gotta fix the small oil leak by the oil pressure sensor. Dealership told me about it, but I dont feel like coughing up 150 for the repair.

 

The more correct term is pre-ignition, but I'm wondering why he's bringing it up. It's not the same thing as detonation, although it can lead to detonation.

 

yea I know its not, thought he was refering to a different time in the combustion cycle.

 

detonation happens in propragation stage.
when the spark plug fires, and creates a flame, and the fuel self ignites causing another flame, and the 2 flame fronts collide, and the piston will knock the cylinder walls on the power stroke.

pre-ignition is when the fuel is ignited before the spark plug fires.

 

Let's clarify something about the oil leak you are experiencing. Is the problem originating from the oil pressure sending unit? I replaced mine recently and it takes all of 5 minutes. I used the Nissan OEM part but I've noticed many .orgers recommend aftermarket replacement as they state the aftermarket part lasts longer. You are being sucked in by the dealer if they want to charge $150 to replaace an oil pressure sending unit.

 

Yea, thats what they told me and right off the bat I knew that there had to be a much cheaper way out. Thanks for that murdoch, i'll be looking up some replacement guides and prices.

 

And less than $5

 

Seriously??, less than 5 bucks? forget the dealership.

 

Yes, pre-ignition is the term given to premature detonation of a charge in otto-cycle engines. It is sometimes referred to as knocking.

http://www.brainyencyclopedia.com/en...eignition.html

Pre-ignition can also be caused by detonation, among other things.

http://www.hastingsmfg.com/Service%2...reignition.htm

 

I guess the easier term I should have said was detonation.

 

I recently had my knock sensor replaced and I bought the car at 92,000 miles, It was a long drive home from penn. to nyc where Im from the "engine service soon" light came on and thats when I heard a knock, the reason was because of a bad knock sensor It ran me about 200.00

 

you could cahnge it for free, and buy the part for 120 or less. But that's a fair price for labor if they took the manifold off, still read the stickys and DIY next time, also, if the lgiht went on taht means that there was another code in there besides the KS, so you might want to pull the codes yourself. Please don't post or ask me how, but instead read the stickys.