First off, I'm going to say that I have changed my KS once before when the car threw the code. I'm now getting knocking and no codes. I use only 91 octane as that is all we can get here in Colorado. Who else has changed their KS without the code, I know there has to be plenty of others who have. What are your thoughts? Thanks.

 

You changed the ks and now you are getting knocking?

 

Check the ECU anyway ... It might be stored. How many miles? I get some slgiht ping under moderate load @ 2-3k with my car I too am in a mountain area with only 90-91 craptane... and a JWT, and when it gets warm, it happens.

 

Hey njmodi thanks for the help......NmexMAN I have 134K on the car and changed the KS maybe 60K ago. I definatly notice the ping under load and even at full throttle in 3rd around 2500-3500K. I guess my question is will changing the KS help alleviate the problem or is this something I have to deal with? Thanks. BTW I have pulled codes and nothing besides a park/neutral code--I need a new switch for that tho.

 

When did you last change the spark plugs?

 

Maybe 15k ago.

 

So the plugs should be fine. When did you last change your fuel filter? They should be changed about every 30K.

 

It's the high alt + craptane + warm/hot weather, normal, read the vehicle manual ...

 

So what's the optimum octane to use at say mile high elevation or thereabouts. I thought it should be below 91 for peak performance.

 

I've always used the best I can get, whether it be 90 or91, but never below 90.

 

According to the owners manual, those in higher elevations can use 85 octane safely.

 

That's what I'm getting at. I would be inclined to try 89 and see how the car runs.

 

I don't think running the same recommended octane (91) would hurt that much, although it will take a slight toll on your wallet. Maybe its just as effective for those who run 94 octane vs. 91 octane at sea level (no negative driveability issues, just hurts the wallet). The atmospheric pressure at higher elevation effectively reduces engine compression ratio, which is why its safe to run 85 octane.

 

I put down 188 Uncorrected in my 03 with headers + GAB .. SAE corrected was 220. That was @ 5200'.

I've seen 04 GTO's (LS1') run a mid 14 up here.... Corrected 13.4-6 .. Blows as.s chunxx. But it's great when you travel to lower alt locations and feel the difference and appreciate it that much more.

 

How much did you pay for the KS? I was quoted 125.00 from the dealership and was thinking of going ahead with the change.

 

Try sleeze 80-90