Couple pics (all different plugs) from the Bosch's I removed. I have no idea how long these have been in - I haven't changed them since I've had the car (about 3k miles). My PO was pretty good with regular maintenance so it's safe to say these have been in no longer than 15k miles or so.

Anyway, I think I've got a little detonation problem at ~4500RPM at high boost (slight crackling...almost sounds like someone is shorting two wires under the car). I think I was goofing up for a while as I was only putting 89 (the 'middle' gas here) in instead of 93. I've got 93 in now with a can of octane booster so it's probably at about 96 and with the new plugs (NGK 6ES's) I'm still having the problem. Not sure what to try next...guess run a few more tanks of 93 through there and see if it gets any better...

**Side question - does the 951 know to adjust for various octane's of gas? I have read about this before and IIRC, some folks said the ECU accounts for that and others say it doesn't.

The only picture I have is from my Hayes book which is B&W but from what I can tell it looks like detonation. Can't tell for sure - so I thought I'd get a few more eyes on it and see what you guys think?

Should I try the NGK 7ES's? From what I've read you should be +75HP over stock to really need them. I've got a 3" exhaust and Lindsey Boost Kit - no way I can be over that.

What should I look at next??? What about the FQS (The **** on the DME that you can adjust for mixture/timing)? I've got the 951Max chips in so maybe I need to make some adjustments there?? I haven't pulled it back out to look to see what it's on now - assume it's stock since the chips I replaced were stock.

 

"Heavy tannish deposits. - Valve guide seals (oil leakage into cylinder) or gasoline additive buildup."

"Brown to Grayish Brown in color with a obvious electrode wear. - Spark plugs are worn and should be replaced."

"Dry black (carbon) deposits. - Mixture is too rich or spark is weak. Can cause miss or hesitation."

taken from clarks garage^

 

Thanks. Wouldn't leaning it out worsen the detonation problem?

At what mileage on the new plugs is a good time to pull a few of them and see what's going on with the new set?

 

I honestly have no idea. I'm still learning about such things, but I trust clarks garage to the letter.

 

i change the plugs everytime i do a oil change. 3000 miles.

 

Plugs should last longer than an oil change. The cheap copper plugs should go 15k miles, at the very least.... Though they also only cost $.99, so an extra $4 isn't a big deal, its just not needed.

You can do a plug check at any time. Install new plugs, go make a few good hard runs for a few miles, then pull them one by one and check em'. If you're running to rich, the insulator will be dark brown. If you're to lean, it will still be white, or very light brown. The perfect plug will be like coffee with a lot of cream. A light, smooth tan color.

 

Plugs should last longer than an oil change. The cheap copper plugs should go 15k miles, at the very least.... Though they also only cost $.99, so an extra $4 isn't a big deal, its just not needed.

You can do a plug check at any time. Install new plugs, go make a few good hard runs for a few miles, then pull them one by one and check em'. If you're running to rich, the insulator will be dark brown. If you're to lean, it will still be white, or very light brown. The perfect plug will be like coffee with a lot of cream. A light, smooth tan color.

 

Thats pretty similar to what my plugs looked like last time I pulled them out. The teachers at school in my high performance engines class were saying they just look like they've been exposed to some high heat/pressure situations and were just worn out. Mine were still working fine despite the iffy appearance.

 

those three prong plugs are junk. Ive run the ngk7es plugs since i started messing with it w/ no problems. The engine knows what octane you have because w/ a lesser octane it'll start to knock sooner on boost and the knock sensor will retard timing cutting power. What wires do you have- junk wires can cause this issue under a load.

 

+1

 

Id stick with the plain old Bosch Super plugs. I tried the Bosch Plat 4's in my Mercedes 190E and the car actually ran worse that my old supers.

 

I've got new plug wires and a new distributor cap (well, ~8k miles new), so I don't think that's the issue.

I ran it hard and pulled a couple back out and they are nice and milky brown. So, hopefully that was just a case of crappy plugs that just hadn't been changed in quite a while. I think I'm going to start changing them with my oil as well. Next time I change my oil I think I'm going to run a 1/3 can of seafoam through the intake as well.

I went with the stock gap of .030. Is that too wide for a car with a Lindsey Boost Kit? I read that others make the gap a bit smaller.