looks lean and knock-ey

 

I think my wideband is taking a ****. This engine has 5k on it since the rebuild and I just finished comp, leak down, and vacuum tests on it.

I did the same testing at 50 miles and 3k miles and I still show identical results and they are still kick ***. compression-185 psi (4), LD-5% (4), vac- steady 18in hg@ idle.

That's the #1 cylinder but all 4 look the same and it runs great. My wideband shows 14-16:1 in cruise and 12:1 in boost. I know that's a little lean but it's a street car and it rarely in boost for longer than 10-15 seconds at a time with long intervals in between.

I never hear knock, but I don't have det cans so maybe I'm missing it?

 

12:1 in boost, richen that **** out.

 

I started out at 11:1 after I installed the rx8 injectors, and I've been slowly leaning it out over the last 6 months or so while continually feeling a power increase everytime I make adjustments. Any lower than like 11.5:1 it feels real boggy. I really need to get this thing on a dyno.

It doesn't help that I really don't trust my wb anymore either. Its an lc1 that I've had for about three years and even after calibration sometimes it doesn't seem to be all that accurate.

 

I run mine at 11.8 target but don't ever let it hit 12+. Your plugs don't look all that bad to me though.

 

pffft i run 12.0:1

Those plugs dont look bad, i see them come out of a stock car like that all the time...

 

I think the plug looks good. This is a good example from mopar muscle magazine.



The spark plug in this picture has quite a few miles on it, but led a relatively good life. There's no evidence of bad tuning, carbon deposits, or of a damaged insulator. Note also that by reading the ground strap, we can see the heat range of this plug is right about where it needs to be. To read the plug and know if you have the right heat range, look at the difference in color of the strap. If the color change is too close to the strap's end (above the center electrode), the heat range is too cold. This means the heat is being absorbed too quickly into the base ring and is not able to burn off carbon deposits effectively. If the color of the strap changes too close to where it is attached to the base ring (the last thread ring), that means the plug's heat range is too hot. This means heat is not being transferred from the strap to the base ring quickly enough. A proper heat range will be shown by the different coloration actually occurring at half the distance of the ground strap. When running the proper heat range, approximately one thread on the plug will also show some discoloration.

 

The implication being that 12:1 is "too lean" under reasonable levels of boost?

Wish I'd have known that when I was dyno tuning my '92. I'd have known that the dyno was wrong about my making best torque in the low 13s.

 

Op when did you pull the plug? Did you do a pull, then immediately shut the car off and pull over or did you casually drive around then pull into the garage? It makes a difference. If you didnt the 2nd like I think you did that plug is great.

Joe I agree. The only car I've really had the chance to play with arfs on the dyno was my wrx but going from the "recommended by all tuners because boxers make more power when really rich" 10ish:1 to 11.8 resulted in 20 more ftlbs and 20 more hp.

 

Its "recommended by all tuners because boxers make more power when really rich" isn't really recommended for power but more for safety. If you have great fuel then good for you, but if you don't have fun rebuilding your motor and replacing those pistons later. I usually target 10.9-11.2 on our 91 camel ****. The extra 5-10hp from leaning it to 11.8 isn't worth it and I've seen so many melted subaru rings over the years that I don't even care about the extra power.

Back on topic though:

I think 12.1 on miata's is a little lean on pump gas, but then again I've never lived in a place where pump gas is actually good (texas? some east coast states?) so I can't even compare.

 

This is why California sucks. 93, all day every day and its only like 6 cents more per gallon than 87.

 

Is that on 93 octane? Just asking, Have you tried using fuel from another gas station and verify results?
It may seem crazy, but here Kangaroo is the best one, Texaco, Shell dont even come close.

Have you tried other plugs, like Iridiums?

What heat range are those?

What is the gap on them?

How is your timing?

They dont look that bad, although I would prefer them to be more brownish looking.

 

Ground strap is too gray/white, which IMO indicates lean at wot/boost. Should be able to see the metal coloration on your ground strap. Porcelain surface change (pitting etc), starting around center electrode, will show detonation first. Black/sooty ring is fat idle. But I could never get a clean ring on my car. It's the gray ash color you should be concerned about.

 

what gas do you guys typically have out there? i havent been to california since i started driving, so ive never seen what there is. i just always hear people complaining about the gas choices out that way.
the gas station i go to is a Sunoco, and sunocos usually have 87, 89, 91, and 93, but the one i go to has 94 in place of the 93

 

AZ, CA, and NV all have 87, 89, and 91. But when comparing our 91 to other states 91 ours is more like a low grade 87 in quality. When comparing to 93 its not even close. And when comparing to pure/good quality 93 like some states have, its downright backwash.

There are like 2 states that have it even worse than us. I forget which states.

I'm not complaining too much though, because where I live e85 is very common and e85 is boss

I'd have no problem running 12:1 on e85.

 

Yep, I have heard good things from e85 fuel.

 

Plugs have 5k on them. That was after a long freeway run getting on it pretty good for about 20 miles, then cruising home taking it easy for about 2 miles. I agree that if these came out of a na engine I would say they look great, I still think they look a little too dry/white for a 15psi turbo engine.

I run 93 octane only, but I have what I would say is an agressive timing/fuel tune because **** it.

I think I'll try adding some fuel and buying a new wb sensor to make me feel all warm and fuzzy again.

 

So, yeah...

I installed the new wb sensor today after work. It turns out I was correct in my assumptions that the old one was ****, as I was seeing 13.5-14.0 afr at 15lbs. The scary thing is that I've had this tune on it for a while.

I have a lot of work to do tonight.

 

Jesus man. You HAD to have det at those afrs, hope all is well inside the motor.