Car is 99 Z28 LS1 with 120,000

I am hearing what I would call "spark plug knock" and I took it to dealer to diagnose

They tell me its not that bad, dont worry about it, and try using a CHEAPER grade of gas with lower octane than 93?

I also have a "chirping" noise that sounds like a cricket that gets higher/louder as I accelerate , but I had 2 different shops tell me now " we cant hear anything" I would guess its a pulley/belt/tensioner but they claim they cant hear it ?

Any advice on what I should do ?

 

Lower octane will make pinging (spark knock) worse. You better find a better place to have your car serviced.

 

+1. thats kinda disgusting that they would say that for knock (if it is in fact knocking). the newer cars are typically almost impossible to hear it in due to computer controlled timing retard

 

You mean, we've been doing it wrong all these years? Oh Man! That's all I gotta say.
And the chirp could be a bad serpentine belt, noisy A/C pulley, worn alternator, etc. Or maybe you sucked in a parakeet?

 

lol

 

Lol indeed

 

I had an exhaust leak that chirped once...that was weird. It sounds to me like you need to have the car connected to some diagnostic software and have someone run it to see if you're setting off the knock sensor.

 

Check your main belt drive tensioner. My car has that chirping sound too. When I removed my belt to check where the noise was coming from I noticed that the tensioner arm had excessive play causing the pulley to misalign with everything else. The whole assembly cost like 40 bucks at advance.

 

Ok here is the deal with that

The car was originally a V6 and someone put a V8 in it. The VIN lists the car as a 6 cylinder. The dealer told me that because of that they cannot adjust the timing or anything computer related because they are not sure what motor is even in there

I am planning to get a 2nd opinion on all this