Need help, detonation?

[BIGONTS]

Need some help figuring out if my car is detonating or what? I had this combo for over two years now and never had this problem. See details in my sig. The only thing that changed when I took it out of storage was a new PA alternator and battery. I had the PA last year and got a new one under warranty. When I took it out of storage, it sounded like I had bearings in my motor rattling, or something. I put fresh gas in it and it still sounds like it at the top of 3rd and 4th gears, but not as bad as with the old gas. Sometimes at to of 3rd and mid to top of 4th I hear it more. I cranked the boost a pump all the way to see if it would stop. It went away a bit in 3rd, but I still hear it in 4th gear. I am seeing 17lbs of boost the highest, that's where it always topped off and where I want it at. If I put a wideband on it, will the detonation show up? How can I check this? I know my fuel system is at border line and I change the fuel fitler yearly, so I still have to do that this year. Thanks,,,

I am going to go through this tank and get some BP 93 and top it off maybe with some 111 octane and see if it goes away. I heard that some gas stations still have their winter gas and it might be kind of old or something???

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[01GTvert]

All you can do is run the highest octane you can find. If it doesn't go away with the new fuel it aint knock.

 

[CREJoe]

Detonation will show itself on the spark plugs. Take them out and keep them identified as to what cylinder they came out of for reference later. You'll need to look closely at them so borrow or buy a 10X lighted magnifier for reading plugs (Jeg's has them cheap). Detonation will show up as little black "pepper" specks on the white portion of the spark plug's business end. If you don't see any of that, especially with boost being pumped into the motor, the problem is probably something else.

Joe
CRE, Inc.

 

[about2bite]

I agree with the above statement

 

[BIGONTS]

Ok, I got somewhere with this detonating thing. I ran all the bad gas out and got some fresh BP 93 octane, 6 gallons. I took a few runs and it was still detonating at top of 3rd and most of 4th?????? I went to another gas station and topped it off, with 4 gallons, of unleaded 100. I took a few passes and no detonation at all, in any gears. So I’m happy about that.

BUT, I do not fee like dishing out the $$ for race gas. My combo has not changed in 3 years. What do you think has changed so I have to run higher octane? Bad gas? Need new spark plugs? Fuel filter?

I changed the fuel filter about 10K miles ago and I have NGK TR6’s with about 12K miles on them. How often are we suppose to change the plugs in out type of applications?

Any input would be greatly appreciated. Thanks!!

 

[Big Cam Z28]

Ok, I got somewhere with this detonating thing. I ran all the bad gas out and got some fresh BP 93 octane, 6 gallons. I took a few runs and it was still detonating at top of 3rd and most of 4th?????? I went to another gas station and topped it off, with 4 gallons, of unleaded 100. I took a few passes and no detonation at all, in any gears. So I’m happy about that.

BUT, I do not fee like dishing out the $$ for race gas. My combo has not changed in 3 years. What do you think has changed so I have to run higher octane? Bad gas? Need new spark plugs? Fuel filter?

I changed the fuel filter about 10K miles ago and I have NGK TR6’s with about 12K miles on them. How often are we suppose to change the plugs in out type of applications?

Any input would be greatly appreciated. Thanks!!

Try running the TR8's. they are the next heat range colder