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They look very clean with a minimal but hard carbon deposit on the face of the steel threaded body. The ground electrodes has a whitish soft deposit on them till close to the body weld. The center electrode insulstors were very white with no visable deposits of any kind. There was a slight coral pinkness at the end of this electrode, just a blush.
I was curious to see how things were going after the recent lively postings on plugs. Debates on the merits of sharper edges on new plugs of the conventional type. With the small electrodes of the platinum plugs, there may be a sharpness effect that lasts for a long long service life. Having used such plugs for years I was a bit disbelieving that sharpness at the same gap would have a pronouced advantage on conventional plugs. But that is something that I have not had to deal with.
These are the factory #6 heat range double platinum.
At a check only at 12K miles the gaps were .036 to .037". I could get a snug .038 into all of them today. I saw the platinum pad on the ground electrode this time. It appears to be around .002 or .003 thick by eye.
I regapped to a snug .035" which is the tigher end of the spec printed on the sticker under the hood. This will give the longest in-gap service life as it erodes open from there.
The electrode ceramic seemed clean as far up in the body of the plug that I could see. I used a bevel cut needle to probe the carbon deposits into the plug body. The deposits seemed light all the way up. But after needling I could see stuff when blowing the cavity out with compressed air. So things seem very clean, cleaner than in the 95SET. Nothing to be concerned about.
I found that the screws were not tight, no surpise. I put loctite blue on these in April, and put more on today. There were lots of signs of movement of the DI casting on the valve cover and visa versa and polish on the DI casting from the screw heads. There will always be movement!
The screws were loose in the NG900s and are much better with the Aero. The screws are now deformed to have three lobes to tighen the fit. That sucks. A tigher thread clearance class would be much better for the tapped holes in the valve cover. I put the screws back firmly with a screw driver with the fresh loctite. That way they will not shake out. I put some neversieze to deal with the fretting wear from the movement. Never try to make the screws really tight to combat their loosening. Accept that the the DI moves, tighten snuggly only and use loctite to make them shake proof. Yes, folks have had these screws vanish.
And some silcone grease on the DI rubbers so that they will not bond to the plug insulators. Don't consider this optional.
The tops of the plugs have a slash of some kind of red paint from the factory.
Before removing the plugs I blow out the plug wells to get sand and dust out. I blew the threaded holes for the ID screws out too, there was some crud in there.
I removed the connector from the DI and found that the red slider comes out of the connector shell very easily. Something new? So I dressed the red slider with a sparing amount of silicone grease, and put some on the sides of the DIs connector too. This may combat the tendancy of these connectors to get locked with grit. Yes the silicone will trap some grit, but it gets trapped in there anyways over the years.
I took the advice of others and maintained the ID casting up as there are some concerns othewise about air migrating into the coils which are oil filled. I found that the connector end can go up by the brake fluid reservoir and the whole thing fits in a slot fore and aft like it was made for this. Then the top of the DI can hold the plugs and feeler guages etc. There are no natural places to put tools and bits when you work on this engine.
The last few mornings, 80F at 7 am, the engine struggle slightly with the first acceleration after backing out downhill. So it will be interesting to see if a .003" change in gap has any effect. Part of the issue is probably low volitility summer grade fuel and the winter grade will be flushed out of the dealer tanks by now. I have been getting quite a few highway commute runs lately with 32.5-34 mpgs. My 95SET had a drop in mpgs in very hot weather. This engine really continues to impress!
posted by 66.139.12...
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