detonation!? - plug reading

[Falco]

Howdy,

I'm figthing against a knock issue lately. I'm getting up to 12 degrees of spark retard at WOT at 17 psi. The weird thing that I'm getting 1-2 degrees even at 40% throttle, no boost. I haven't heard any knock myself so far, not a single one...

I've already tried several things, but the main question is wheter I've real knock or the sensor picking up some false noise. I've put in fresh plugs yesterday to make the reading easier and made a few WOT blasts, getting macho knock acording to the ECM. I've checked the plugs, all look the same:

I'd say I've no knock, but pls take a look at the black spots in the two circles I made. I'd be happy to hear a few opinions...

Thanks,

 

[Lynn D. Brown]

KR

KR

Falco,

Those marks on your plugs do not appear to be significant. The effect of detonation problems on plugs R more obvious than this. The big thing to watch 4 is a whitish deposit on the plug electrodes, indicating a lean condition and soaring combustion chamber and EG temps.

 

[myclone]

What kinda gas were you running? I cant really make out what the black spots are but compaired to the rest of the plug Id say they arent significant (IMO). Looks like you are just a tad lean but not much at all. I dunno your chip or engine combo so that plug may be the norm for you.

 

[SY2932]

If your plugs look like a fly took and poop all over them, you have a serious problem. However, they *seem* ok.

Mike Campbell

 

[Falco]

Thanks guys, I really appreciate your help and opinion. My AFR is in the 11.5-12.0 range at WOT and I was using European 98 octance gas (93 in the US). Anyway, after a sleep and reading your posts I strongly belive that I've a false knock. I can hear some strange clacking noise, but only when I'm on the throttle. I guess I'll think this over once again and might do an other post about that noise...

Thanks again,

 

[Buster]

I'm feeling very posty today. If you decide to relocate your sensor, I've found a nice spot. You know where the stock turbo coolant line used to screw into the lower intake manifold? I found a brass 90 degree adapter, screwed in a reduce to fit the hole in the manifold and then screwed the knock sensor into the other end, it'll be out of the way and look pretty stock like, and in my experience it works very well to pick up knock.