hello camaro nuts. I'm in a pickle I have a 1984 camaro z28 with the 5.0 ho L69 motor in in. the emissions pump lines and cat have been removed for none emission County here in.collrado before I owned it. The car is perfect and all I've had to do was rebuild the computer controlled carb. Anyway the other day it started making a slight knocking noise and seemed to of lost some power in it when you.step on the gas. and the knock seems to of gotten a bit louder. Even after a fresh oil change and a little extra 50 w oil for extra viscosity incase it was a connecting rod knock, it's still there. I read on a different fourm that it could be the knock sensor because it started after I filled the tank with 85 Oct and I read that your supposed to use 91 because the new 84 L69 had higher compression and would retard timing to prevent knock and ping. so finally my ? is would a bad knock sensor be the cause of my knock sound and loss of power be the timing retard? thanks so much sory for the lengthy post.... sasquatchZ28....

 

If yours requires 91 octane, the 85 octane (didn't know you could get so low) you put in is most likely all that's wrong. Run some gas off, or siphon some out, and refill with premium. Or, add octane booster to what you have. Your computer might not be able to retard the timing enough for the 85 octane, which is what it would be doing. This would result in knocking and a loss of power.

 

thanks camaro69. Could it really just be the 85 Oct I put in it? my oil pressure is great above 30... and it makes the knock noise under a load and not under a load. Any other possibility it could be. This is my first camaro and I've waited 20 years to get her and now this. I'm wicked bummed . Any other advice or diagnosis would be much aperichated. thanks sasquatchZ28.

 

I didn't look up your engine's octane requirements, look under the hood for your emissions sticker to confirm. But if 91 is in fact required as you say you found, then when running a lower octane gas, the knock sensor is going to tell the computer to retard the ignition timing as it picks up any knock (before you can hear it). But as I said, the computer might not be able to retard the timing enough for the 85 octane, and then you'll get an audible knock. Octane knock happens when under a load. Based on all you've described, cheap gas sure sounds like the culprit.

 

I have three quarters of a tank in there right now would one of those 104 plus octane boosters work

 

it may help but run the 91 or higher like Camaro 69 never heard of 85 octane where are you from

 

Colorado. north of Denver about an hr

 

huumm did not no the us sold anything under 87 I found a forum says 92 to 93 but then guys will argue 87 works fine,,i would try as high as possible like 93 or 91 like said then work your way down as to what works best ,hear we got 87 89 93 an 91 only ceratin stores have it,its Beauitful out there ,I went through Colorado one time an seen the white wall ,a lot of people don't relize near half the state is flat land from east to west

 

awsome I will try asap thanks.

 

He's in Colorado, a higher altitude (not just because of legalized weed, lol). Because of the thinner air, an engine can run on a lower octane fuel. Less dense air = lower cylinder pressures.
91 octane might be the highest one available for where he's at.