rotarygod

This comment has gotten my attention since it makes no sense. Oil is injected into the engine based on rpm and load. In stop and go traffic, more oil is needed than it is just sitting at a steady rpm cruising. This post seems to suggest that alot more oil is injected during cruising speeds as opposed to stop and go. This is totally backwards from what should be happeneing. Why inject more oil when the engine doesn't need it? More oil in the combustion chamber is more that can break down into carbon. We should be seeing less oil consumption during long trips, not more.

Just to address to those that don't know, here's why the Renesis has this problem but the older rotaries didn't. It is absolutely because of the exhaust port location. The peripheral exhaust ports on the 12A/13B engines would lend themselves to easily let things out of the engine such as carbon. Actually it's because too many hydrocarbons would go out that Mazda changed the location so it even effects gasses. Carbon did build up in the older rotaries. If a piece of carbon flaked off, it would get pushed around until it came to the hole in the chamber (exhaut port) and it would go happily on it's way. With the Renesis, the ports are on the side housings and not against the apex seals. When the apex seals push a loose piece of carbon around, it has no hole to run across and more easily stays in the chamber. Some does get out though so it isn't like it indefinitely stays there. Mazda knew there were issues with this and this is evident by the shape of the exhaust ports. The closing side of the Renesis exhaust ports is shaped very strangely. It is a very mild slope out of the port itself. This does nothing for airflow through the port. What it does do is to leave an area for carbon to slide out of the port as the side seal crosses over it. Without this bevel, the carbon would hit the cloing wall of the port and stick up into the path of the side seal which could potentially be bad news.

Mazda actually did try the side exhaust port configuration back in the early '70s but couldn't get it to work good. The big problem was technology. The tests they did run confirmed that engine efficiency would go way up and fuel consumption and emissions would go down in relation to power output. Their problem was with breaking side seals from carbon buildup at the exhaust ports. See any similarity? They decided to abandon this configuration until they could sove this issue effectively. Back then all of the engines were carburated. They too injected oil into the engine but at a rate several times higher than modern rotaries. With the newer seal compounds and better housing coatings that allowed for less friction, this oil consumption requirement has gone down over the years which takes us to the Renesis. Mazda felt they could adequately make the side exhaust port configuration work now based on this newer technology. There will always be a small degree of carbon buildup as long as you are injecting motor oil into the combustion chamber. Can't get around that one. The side seals in the Renesis are different from those in older rotaries in that they are wedge shaped rather than flat. This allows their sliding motion to push any carbon out of this seal groove. Mazda knew good and well that the side exhaust port engine would have more carbon issues than the older rotaries but were most likely better that the small amount left wouldn't cause any issues. Obviously it can in certain cases. If injecting too much oil into the engine was an issue that led them originally to not use side exhaust ports, why would they potentially even run more oil than they have to in the Renesis. Seems like they didn't learn anything. We'll see how they end up resolving this issue.

Mazmart

iTrader: (12)

There are a lot of good observations along with some strong speculation in this thread. Keep that in mind. Great thread though, and RG, you have spoken some more rotary truths that a lot of people would have been quite unaware of here.
Good stuff!!
Paul.

bxb40

I agree with the idea that MAO should inform customers of the changes a flash does. My last experience is even worst: consistently after a visit to the dealer to get the new oil dip stick installed, my car gets 3mpg less. I just could never explain it until MAO told me, on an unrelated issue, that the last dealer installed the P flash (car came with M). At no time the dealer told me they will do it or even mention it in the paperwork I got. They only reported it to MAO so that they can get reimbursed...
So the way I see it, it is either us paying extra for gas, or MAO paying extra to replace catalysts. And guess who and how wins?!? Needless to say, I'm not going to that dealer any more (for other reasons, though in the same class with the above practice).
As for the AT problems? I drive it at high RPM 3-4 times a day, and am using premix since after the engine break-in period. Car runs nice but something rattles in the catalyst when it is cold outside (so now the car is very quiet )...

RotaryIT

Realistically, I dont blame MAO for not notifying me of new flashes. There is no guaranteed way of making contact with each owner without some great cost. Consider the costs that MAO is already bearing for the costs of reflashes, new cats(for some), and any and all of the other TSB, or warranty related issues.

If they did notify all of us, and explained what the reflash would do....what should they do if you refused it? Void you warranty? These reflashes are not considered optional...IMO, if they were then why would MAO spend so much time and money creating new ones?

Personally, I would much rather have MAO reflash my car to what they want the car to be, then to have left it the way it was when I first bought it. We all have disagreed with the responses about oil consumption, or fuel mileage at some point..."it's normal".

That's like being an engineer and deciding what the car should do and shouldn't do, how it should and shouldnt perform as an owner, and not an employee/engineer/designer...whatever we want to call them.

I'll still leave it up to them.

zoom44

contacting each owner for each new flash would be rediculously expensive. i agree. but having a decent laymans terms explanation as to what the flash will do to the car i think is necessary. right now i cant think of one service cemter in my area that i could go to and get ANY kind of answer to the question"what does it do" besides "i dont know".

if they said i needed a new clutch and i asked them to show me why- they would point out how blue the disc is and show me me a new one and explain the difference. in fact the y have to. same with any part of the car. If there is a recall for anything- say airbags- they have to explain to me what the change is and get this- i can refuse to have it done. im saying we should have the same choice on flashes.

what if the next flash decreases my fuel economy but it lowers oil consumption. some would think thats ok and get the flash. i might decide to wait until the next flash because then they might find a way to bring the MPG back up . why shouldnt i have the right to make that informed choice? maybe we do but they just arent giving us the info.

hey Paul- thanks for the kind words. you are right of course. alot of this IS speculation. but i hope that it is well informed speculation that can help others to understand and hopefully help us all figure out just what is going on. got any input from your years of experience or from some of the folks you know like Mr. Engman?

PUR NRG

Minor data point: current MOP P/N is N3H1-14-600C so they're on the third or fourth iteration. Retail cost is $1200 because it's computer controlled.
________
Mexicocity hotel

olddragger

iTrader: (3)

Guys,
This may be totally unrelated but I remember the infamous "judge Itto" posting that he expected apprx a 10hp lost after so much wear and tear on this engine. If I remember correctly he was questioning the seals. He ran the dog do-do out of his car and he definity didnt have a carbon problem. He also said it would be a top end loss. He got blasted but I can't help but wonder.......hmmmmm. Any compression checks going on out there? I know --idles are good etc but they could be ok till the power is on. Increased MOP does help seal the seals. (sorry couldnt help that). I mean what RG says makes a lot of sense. But could it be the more than just carbon buildup? Bad seals would make the engine replacements thats been going on in Texas more lodgical also. I honestly dont know I just cant help but wonder.
old farts need more to do! We think too much!
olddragger

Marietta 8

This weekend will be spent installing Tein Flex on the mighty Mazcare 8 after I get done with a tuning session on the mightier Mazcare LS1 7. While I have the car in the air I will perform a compression test for our amusement and interest. I did perform this test at 1200 miles before the baseline dyno test. What I immediately noticed was the slow cranking speed (200 rpm). Earlier RX's normally cranked at approx. 250 rpm or better. The result is lower compression readings due to the lower cranking speed but the numbers were still acceptable and certainly within spec for the cranking speed. The new compression reading will undoubtably be higher due to the new battery/starter combo as well as 13000 miles. Oil consumption has remained constant since engine break in was completed and power has verifiably increased with every flash. My automatic owning customers have been very happy with the results of flash updates and one for sure has commented on noticeably better power and mileage.

As far as carbon build up we have seen great results from BG products brand 44k as well as chevrons Techron. Both products are pour in types and best result are gained when used with a full tank of fuel so it can work longer. We have used 44k for 13 years in my shop with great results. Techron is also very good and easier to find. I am keeping close tabs on several of our customers 8's and recommend bringing them up to date on flashes due to the results on my car and several others. There have been no complaints and many thanks after updates.

I'll post compression readings sometime over the weekend.

olddragger

iTrader: (3)

ok charlie what did you find? Although obviously your car should have great compression. its the ones with troubles that I think MAY be having problems.
olddragger

zoom44

just a little info

so they arent replacing that engine but waiting on a flash. flash delayed(says dealer) because it didnt fly with the EPA first round. and while waiting, dealership wants to clean it BUT they want to charge the customer for the cleaning and customer had to FIGHT with Mazda to get it under warrenty.

okstatepike

Well, that is interesting. My engine replacement should be done in a day or two (absolutely DYING to get it back!), and they have been nothing but gracious since they "found" the problem.

Interesting that in this case a PCM flash seems to be the proposed fix, it doesn't quite jive with what my dealer's service mgr. told me. Zoom44, was the issue you posted above verified to be low compression?

Marietta 8

Sorry for the delay on the compression numbers. I ran late, drank a heiny and just didn't do the compression test. The good news is the Teins are on. I'll giter done tomorrow night.

Chas

olddragger

iTrader: (3)

More hineys Charlie?
OD

Razz1

No I think he fell off the wagon and drank some Bass Ales.

olddragger

iTrader: (3)

Girlfriend must have him
lol
OD

zoom44

when i last left this thread we were hearing that a flash might be comign once it passse by the epa. we got a new flash today but as yet we dont know if it addresses this problem or not. hopefully one of the effected people will get a call saying"come ina nd get your car flashed. how about it jerryf?

zoom44

bump- the engineer teams have been spending time in vegas and elsewhere onthe at engine failures. no word yet on an ultimate resolution. if anyone in vegas rusn into the engineer teams have them email me at zoom44@gmail.com thanks

zoom44

see Kevin now i get this. I didnt understand why they wanted more oil. more oil equals more carbon which is bad. but hot oil is thin oil. thinnner oil doesnt help the seals do their job. so MNAO starts seeing compression loss. they think "lets try to get more oil at the seals" but its not lack of oil its the HOT thin oil. did you read what jay goldfarb posted on his oil temps? 240-250 on the track. 210 on the street in traffic thats crazy hot!! and his is an MT, the ATs only have one cooler. not enough oil cooling.

Nemesis8

iTrader: (3)

Do the oil coolers need fans also I wonder? How are they going to reject heat without help?

rotarygod

As long as you are moving they are getting plenty of cooling. This obviously doesn't help in traffic or at a stoplight. I personally feel that small fans should be installed on the back of the oil coolers. Maybe even larger oil coolers and better ducting on the backside of them.