mdeserteagle50

OK...I have an 87 N/A DD....This car has 121,600 miles on it....It is still running strong to my surprise.....But my problem is that it runs rich as hell.....I was told that replacing the mass air flow could sometimes solve this problem.....But at the same time I wanted to change the intake gaskets b/c maybe that might be the problem....But, being that these cars are so finicky I don't want to take sumthin apart and then she doesn't want to crank...I am not having problems, i just get tired of the smell and the bad gas mileage....Or maybe this is just how they are.....I am a mechanic but when it comes to rotaries, im in the dark....Can someone shed some light here????

Sauxons

My 13B runs rich as well
I'd like to know how to fix it as well

joel_rx7

iTrader: (7)

Rotary engines run rich, this is not something you want to fix. Even though a Wankel engine has a 50% longer stroke duration, the combustion chamber shape is sort of longer and narrower (compared to a piston engine). This tends to lead to incomplete combustion as the flame front will have a longer distance to run (it propagates in a less uniform way than on pistons engine). Therefore they have to enrich the air-fuel mixture a bit more.
Running rich will then give you higher HC and I read in wikipedia another reason why they would enrich the mixture even more. Having higher HC than usual will need a more expensive exhaust after treatment (catalytic converter). By enriching the mixture even more they create some sort of secondary reaction that will burn HC (they say in an enlarged open chamber in the exhaust manifold - pre cat??? I have only had my FD for 3/4 months and have not looked at that part). Wonder how they do for CO then....at least NOx must be nonexistent.
Of course it's like fuel price wasn't an issue at that time

I have been struggling to find fairly detailed description of rotary mode of operation and tuning, well if you think about it there only a handful of guys that know about that in the world (and they're all in Hiroshima...). So any comment are welcome.

mdeserteagle50

ok.....that helps.......so thats why when you put on a more free-flowing exhaust on the rotaries(especially turbos) you can really tell a difference in the feel and power of the engine........Or am I wrong?

joel_rx7

iTrader: (7)

I'd say that putting a less restrictive exhaust has more to do with the fact that it will let your turbine spool quicker (hence higher intake air pressure, hence more torque, hence more power).

mdeserteagle50

ok....now i understand the fact that rotaries are designed to run rich based on the information you gave above.....But from my experience working with pistons, when you can smell gas coming from the tailpipe and black smoke thats thick as hell, there's a problem......Also, whenever I bring it into the shop, I can't have it running long even with the doors open b/c no one can breathe in this bitch.......But maybe I am looking to much into it......Like you said, this is how they are made........

joel_rx7

iTrader: (7)

If that can help, it's the same for mine. You want free gas? Find a way to recycle the one out of my tailpipe (especially when idling..)
But I am not saying mine does not have a problem (I hope and think it does not, it's just what I heard and learnt from rotaries).

mazdachump

iTrader: (3)

try turning the variable resistor on the passenger side struttower to the lean side

mikevoch89146

iTrader: (1)

The variable resistor is also good for faking a smog pass.

mdeserteagle50

Ok....will turnig the variable resistor to the lean affect performance???? We dont have smog tests in richmond, va yet.....Not trying to jinx us because i heard it was hell for rotaries to pass!!!!

RotaryRocket88

iTrader: (7)

You have to jumper the initial set coupler by the leading coil before adjusting the variable resistor. Once you do adjust it, it will only affect the mixture at idle. Once you increase engine speed, the ecu map will take over.

Does the car have cats & are they in good condition? They should be taking care of excess fuel vapor in the exhaust.

How much oil is the motor burning? Gray / black smoke is indicative of excess oil in the combustion chamber. Does it go away after the car warms up?

rnz520

iTrader: (10)

If the MAF sensor is bad you can usually tell, my S13 was pretty atrocious, like a constant flame out the exhaust and 10MPG, not to mention it washed my oil down and had to change it. This is interesting how rotaries are so different.

Rotarded-at-last

I hope i pass smog!!!!

mdeserteagle50

Well, from time to time there is a lil bit of blue smoke when I crank her sometimes in the morning.If it isnt driven daily....I already know the engine is going, just basically driving it till it dies. Got a couple spare 13b's that i got and hopefully I wont have to hunt for any more housings, I can just use what I have...
As far as the cats, there is only one, and its basically non-existent....The car doesnt burn oil, but for some reason it leaks it by the oil filter...Changed the oil filter dozens of times, used different brands, but i only tightened the way your supposed to. And I have never double gasketed.....