You can't read rotary plugs like piston engine plugs

re: deeper seals, you're welcome

 

Humor me. I'm not saying read them for AFR, just for any deformities or anything abnormal.

 

Sorry man, I forgot to post this...

 

me too

 

Ceramic on both trailing looks way too white, both leading look a bit worn, but the one on the left looks worse. Left set from the rear rotor?

If you could take a picture that shows the ceramic insulator a bit better I'd appreciate it. I'm guessing the rear rotor had some serious sustained detonation.

 

Harlan,
could you elaborate on your plug readings skills?

is the white an indication of lean?
those are platinum plugs they ware down fast!

how do the left ones look worse?

 

Normal plug insulators are tan to light brown in color. If the plugs are darker that means they are not getting hot enough to self clean, if they are lighter that means they are getting too hot and all the deposits are burning off the insulator.

Plugs can get too hot by either operating outside of their heat range, or because of minor knock breaking down the air layer insulating the plug and causing it to get hotter.

Here's a good reference.
Verrill: Plug Color Chart

The plug color does not by itself indicate running lean, it just tells you what temperature conditions the spark plug is seeing.

The leading plug on the left looks worse. The center electrode is more rounded and the outer electrode looks slightly deformed/melted. I don't think it's wear because wear is usualy more even (because electricity takes the path of least resistance). Might just be deposits, hard to tell from the picture.

My guess is that the plugs saw long term detonation and/or were well out of their heat range.

Here is another reference:
Post your spark plug photos here - RX7Club.com

Oh and your right the platinum plugs wear pretty fast. The stock iridium plugs are awesome for wear characteristics, just require a cleaning from time to time and for NA they will last a long time.

 

Recently twigged to all this myself and now run 10.5s and 11.5s

 

you're humoring me

 

Sorry guys, I'll have to see if I can determine the order of the plugs. I got hasty and moved things around. Also, they are not platinum.

After examining the tear down it looks like I'll be in for at least the rear and center irons, rear housing and rear rotor. I found a running engine in a wrecked car at the local wrecking yard. 77K miles, $1800. I watched it start up and run. They have a 90 day return if the motor fails. I figure this will get me back on the road for the time being. It also includes all the ancillary stuff like intake, wiring harness, etc., so lots of spare parts. I will keep my old motor parts and perhaps rebuild it with deeper apex seals, dowels, etc. over the winter...

 

you should at the very least put better apex seals in this wrecking yard find, no sense in killing more housings

 

I don't plan on pulling it apart right now and I won't be boosting on this motor

 

Gotcha

 

Donor motor is in, fresh bath. Cue up Aerosmith: "I'm back! I'm back in the saddle again!"

Exactly one week to pull the old motor, tear it down, find a used motor and install. I feel pretty good for a first timer. I'm saving my old motor for a proper rebuild over the winter

 

With a boost renesis I wouldn't wait till winter....

Jk bro, seriously though good work completing within a week.


.

 

Good work man . How are you liking the newfound torque ?

 

Lol I hear ya man no boosting on this motor for now...

 

I loved it while it lasted! I'll be back at it tho

 

I meant the new-found NA torque .....................

 

Shaddup

 

So I found something interesting that may have been the root cause of detonation leading to the apex failure. The weekend before autocross I changed the oil and overfilled just a bit. It was a little over the top of the flat part of the dipstick. Right after the racing on my way home I noticed the car was running really rich in cruise. Eventually it seemed to work itself out but then after the motor popped I noticed it running leaner. Since putting in the replacement motor I've noticed erratic fuel readings. I started digging around and found quite a bit of oil in the intake. I pulled the MAF last night and it was pretty well coated in oil. I gave it a good cleaning and today fuel readings have been much more stable, like prior to racing. So my current theory is between overfilling the oil and sloshing around the MAF got coated and wasn't reading right and at some point it went lean under boost.

 

After cleaning the MAF I started pushing things a bit and was finding it was still going lean, so I started systematically checking things along the fuel system. I checked the fuel pump filter sock and it was clean so I swapped the fuel pump with no change. Looking at logs Fazda was getting suspicious of the P2 injectors. So tonight I broke down and tore into things to pull the injectors out. I checked each one with 12v and they all opened just fine, so none were stuck. I could blow through each with the same resistance. I know its not exact, but at least I could tell none were sticking closed or completely failed. I cleaned each one and put things back together. As I was inspecting the UIM prepping to put it back in I found this nipple cap that was pretty much eaten up (by what I don't know). It was on the nipple on the underside of the UIM just behind the TB. It practically fell off when I started to pull on it. I can actually blow through it the cracks are so bad. I replaced it with a new one. After putting things back together my fueling issues have disappeared. Either it was this nipple cap or cleaning the injectors... Regardless, its nice to have torque again

 

I suggested somewhere previously just ordering the Mazda OEM nipples used on the LIM, just bought 10 of them myself not too long ago ....

 

Is it common for them to deteriorate like this? I haven't seen it before. Would the Mazda caps be any better?

 

Most of the aftermarket vacuum caps are cheapo material not intended for rotary engine type heat conditions