I'll check my flash tomorrow, left my laptop at GF's.

 

 

I have an '05 with about 21k on the clock, and for several months now have had the dreaded marbles-in-a-can (MIAC). Actually, to me, it sounds more like BBs in an Altoids can. I've had it on acceleration, all the way from about 2k all the way up to redline. It is quite pronounced, and I've asked the dealer twice to look into it. Both times, they've told me to "use higher octane gas", despite that I've told them more times than I can count that I use 93 octane at all times. To boot, when I purchased the car, I carefully monitored my mileage, and was consistently around 19.3 miles per gallon. Lately, that's been more like 16.4mpg. I'm guessing that may be at least partially due to winter gas formulation and cold weather, based on what I've read here.

Anyway, after reading this thread, I decided to give pre-mixing a shot. About the only decent quality oil I could find locally was Pennzoil Marine full synthetic 2-cycle. I picked up a metered funnel, and added 6oz. to my full tank.

First off, it appears that I'm seeing gains in my mpg, though that's subjective at this point. All I can say is that recently, when hitting 100 miles into a tank of gas, I've been sitting right at the 1/2 mark. On this first tank, at 100 miles, I'm about halfway between 1/2 and 3/4. So far so good.

Most importantly, as others in the thread had noted, my MIAC are either significantly diminished, or have gone altogether. Now, I'm no mechanic, but I'm assuming that adding oil to the gas would not boost the octane...and that perhaps it would actually lower it. This leads me to believe that my MIAC are definitely not related to the octane of gas I'm using, and more likely is related to sealing/compression issues in the rotor chambers. Can I assume that the MIAC is due to possible seal failures...even if the failure is minimal? If so, I'm wondering if I should stop premixing and just wait for the engine to blow up, so that I can start fresh with a replacement. I've yet to experience a noticeable power loss...and the car now sounds like it did when I drove it off the lot.

Any thoughts from the rotorheads?

 

you can always have them do the recall test and see where you stand.

 

Had the recall test done a few thousand miles ago when it was announced...tested fine. But, I had no MIAC at that time. Thanks for the suggestion though!

 

I had my recall check done twice about a year apart. The first time it was fine. The second time my engine was replaced. :dunno

Also I agree the premix is improving the engine compression. My hypothesis is it's reducing the side seal leakage. The Speedsource guys said the side seals on the Renesis have larger clearance gaps than previous rotaries.

 

Hey Shaun...just out of curiosity, did you see a gradual decline in your fuel mileage before your engine was replaced? I'm wondering if the seals slowly fail over time, leading to a gradually increasing loss of compression (and fuel economy) until it actually craps out. If this is the case, the fact that I've lost about 2-3mpg over the past several months leads me to believe that mine may be gearing up for the graveyard.

Maybe I should start a poll asking that question of folks who've had engine failures.

 

It's not the sides, it's the apex and corners seals that wear quickly in certain conditions.

 

Well, that depends.
The oiling situation affects the corner and side seals.
The drop in compression is almost always the side seals.
Catastrophic failure is usually the apex seals.

The big issue with the Renesis is that seemingly excessive clearance is intentionally designed into the side seals to help deal with their constant expansion and contraction as they are alternately heated and cooled by passing over the exhaust and intake ports.
The corner seals also pass over the ports to some extent, but are better supported than the long, thin side seals.

The apex seals actually require very little oil. This is part of the reason why the Renesis has two oil nozzles per chamber instead of one like its predecessors.
The nozzles are aimed at the sides of the chamber to help cool and lubricate the corner and side seals.

 

What would have caused my own excessive apex wear and ruts in my housings from the corner seals while all others were in good shape?

 

Detonation.
"Catastrophic" detonation is something that you have heard, no doubt. That's the "crushed soda can of death".
However, detonation and abnormal combustion pressures don't always manifest themselves as noise and motor destruction.

The corner seal tracks are caused by the heating I mentioned above.

 

Yeah, that would be called "inaudible detonation".

I wonder how long I would have been experincing detonation to have the ruts worn in my apexes last year like I did.........

 

It's tough to say because my driving habits changed significantly. I went from driving 80 miles per day to work and back on the highway to just driving on the weekends and mostly city driving.

I did see a decline but I can't say it wasn't due to my change in driving habits. I suspect though if you've seen a significant change in mileage without a change in your habits that there's been a change in your engine.

 

Could have been a single event. Could have been mild detonation over a long period.
The corner seal tracks take a while because of the relative hardness of the end plates.

 

Yeah, my driving habits haven't really changed at all. If anything, I've recently been driving more conservatively with the weather, icy roads, and such. I guess maybe I'll use up the syn-2 stroke I bought, then go back to no premix in hopes the engine just up and dies before I hit 60k. Hrm...based on MM's comments, sounds like my side seals are perhaps prepping to die. Dammit. I love this car too...makes me sad.

So MM, the MIAC is likely caused by the excessive gap in the side seals and detonation?

 

I have yet to conclusively experience what has been generally called "MIAC".
Detonation is very distinctive - it sounds like someone crushing an empty soda can - and would not be produced by anything that causes lowered compression.

 

I suppose what I have could be described that way....kind of a very rapid popping sound...almost like the sound from one of those old Jiffy Pop containers when using one over a stone...kind of metallic. Only hear it under load, and generally under more spirited acceleration. Sitting in neutral, engine sounds as smooth as butter. It's present at any rate of acceleration, but more pronounced when ya put your foot in it. Definitely NOT from behind the glovebox, and definitely coming from the engine compartment.

Maybe I need to try another dealer...one that isn't quite so lazy.

 

Mine has made some noises, and sometimes it sounds like mild Detonation in a higher gear at low RPM.

Same sound happens sometimes when you rev the hell out of it.

But the MIAC I have heard has always been the air bubbles in the heater core.

I don't get that gurggle (MIAC) anymore. I still think it's the feedback from the ports opening up.

It's never has been as loud as crushing a can.

 

Roll the windows up, go somewhere quiet and reproduce the noise (a suggestion that makes my skin crawl, but its your car).
Does the sound emanate from the middle or right of the engine compartment or from somewhere a couple of feel in front of your left foot?

 

Well...I don't really have to try hard to reproduce the noise. It does it on normal acceleration. Tends to pick up at around 2.5k, and continues up until the noise of the engine winding up gradually drowns out the rattle until I can't hear it. It's intermittent though. Since I tried a tank of pre-mix, the noise is quite a bit reduced, and about half the time completely absent.

It sounds as if the sound is coming from directly ahead of the center console, within the engine compartment. It's definitely not in the cabin. Just filled up on 93 octane again today and am going to re-try a tank without pre-mix to see if the sound returns. I'll try to do a better job of pinpointing it. Oi...this just makes me feel sick...

Also, this was a bit weird, but yesterday I hopped in the car, and while I normally let it run about 30 seconds or so when cold, I took off immediately. I think I was a little lax on the gas when I released the clutch...the revs dropped, I heard the rattle (along with a whine that sounded like a slipping belt) very briefly until the RPMs caught up. That one freaked me out a bit.

 

OK. Well, its pretty safe to say that is NOT detonation.
Its most likely an intake valving (SSV or APV) tolerance issue.

 

Noob translation please? How loud would one describe TRUE detonation then?

 

You will hear some *popping* noise from somewhere down there.

 

Idemitsu Racing Rotary Fuel Lube (Premix) - Synthetic Blend

Got this off www.mazdatrix.com
So are all Premix synthetic blend? or does Idemitsu have a non-synthetic blend?
and is it ok to use the synthetic blend if I'm not using synthetic oil?
Just wondering.
Thanks,
-Gil

 

I've been using Idemitsu in conjuction with the Sohn adaptor for over a year now and as far as I know, Idemitsu has only one type of premix.

...you should be able to use premix regardless of what oil you use, using a syn blend premix has nothing to do with the type of oil that you use. The premix goes in to the fuel tank or premix reservoir (if you have the adaptor).