Hello,

sorry to come up again with a prob, guess probs is a price to pay for old cars.

Yes its no joke, my oil level is climbing. Last week i checked oil on half cooled down engine and found
the level +- 5mm over the "F" full mark.
Thought its because it is warm or it could be reading error.
Running Castrol edge 10W60 all year round.

Did check it 2 times again once with cold engine and once 1 hr after ride, still 5mm over "F".
Used a flat surface to park the car on.

Was confused about the fact that my oil level is climbing, I did put about 1/4 l of oil in it
few months back (ca 1.5k to 2k) dont remember exactly, to reach the "F" mark. Now its 5 mm over "F".

Found out the dipstick smelled like gas, so I checked oil filler, removed the cap and it smelled like gas real good.
(Real good means you can clearly smell the gas in the oil filler, of course it smells like
oil too but the gas is very noticeable)
I am wondering how gas comes into the oil pan ??

I am always taking good care of my 7, but this time I guess there could be hiding
something bad inside my engine.

car:
1986 gxl NA stock engine, 1 st motor (139k km)
RB ignition wires and new coil
New plugs and oil 3000 km before
0,5 l premix to full tank


Any help is greatly appreciated

Thank you very much
Steven

 

an overly rich running condition or flooding issue will put fuel into the crankcase.

 

Hi Karack,

thanks for your answer.

Yes my car is running rich, I know that rotary engines are running a bit rich from factory but mine could
be one of those who are running still richer. I can smell the raw fuel when cruising
with opened roof.

It does not flood, at least I havent had the problem.
Sometimes it can get a bit tricky to start when hot (shutting hot engine down multiple times in a few mins)
It takes 2 or 3 seconds more to start then, thats all.

I get 330 km out of a full tank. Accidentally I found out last week that after 350 km the engine shuts down
due to empty fuel cell.

So nothing more than 330 km to 350 km on a tank.

Regars
Steven

EDIT:

Can you explain me how fuel comes into the oilpan due to rich condition or flooding ?
I dont get this right away.

 

330km, if highway is fairly poor for an RX7 so it may be quite overly rich due to various reasons.
the main reason for running rich is improper idle setting, misadjusted TPS, ignition timing, worn spark plugs, faulty leading coil or fuel pressure regulator. an oversized or rewired fuel pump can also overpressurize the injectors and cause the car to run overly rich, if it has an upgraded fuel pump, faulty pump relay, or rewired fuel pump directly to the battery without any fuel trim computer to adjust it.

the fuel makes its way into the crankcase when the chamber is saturated with fuel. under normal conditions when running the fuel is in vapor form and never liquifies on any internal surface before being ignited and burned by the combustion process.

in overly rich conditions the fuel can be sprayed in much larger than necessary amounts which coat the internals with raw fuel while the engine is running. the raw fuel is pushed past the oil seal wipers as the combustion pressure is much higher than the crankcase system pressure while the engine is running. worn side seal clearances in conjunction with rich conditions will cause this to go a step further with excessive oil system dilution.

 

Thanks Karack for the explanation, now I got it.

Forgot to mention that I have a K&N drop in.

I tried to improve the MPG, this led me to change the already rotten ignition wires
with RB silicone ones (damn expensive), and I did put a new coil in, had it laying around so why dont use it. (Brand new Bosch coil)
It feels as if the engine is running smoother than before the changes.
But nonetheless it does *pop* sometimes when shifting, sometimes quiet, sometimes very loud.

New plugs installed as mentioned.

The rest is all stock, stock fuel pump/relay/wiring.
Secondaries are working at 3800 rpm, I can feel them kicking in.
I am using 95 octane over here, the lowest I can get.
The engine is pulling strong from 1500 to 8000 so I guess it has good compression.
I can measure its compression tomorrow. Got a new tester.
Idle is nice too.

TPS can be checked and adjusted, correct ? I remeber crossing about a how to for doing this.
-> Putting on my to do list

Assuming I did a tune up, and the car is not running excessive rich anymore. Does this
reduce the fuel passing to the oil system significant ? So after the oil change it wont climb anymore ?

Regards
Steven

 

Update:

I adjusted the TPS (engine to op. temp.) with the resistance method.

Was set at 1,2 kOhm, I set it to 0,99 kOhm. *yeah*
Ideally it should have 1 kOhm (http://fc3spro.com/TECH/HOWTO/TPS/tps.html)

I noticed:

TPS is increasing resistance properly as expected until 4,6 kOhm there it stops.
This is equivalent to about 60 % of throttle.
Shouldn t it go to 5 or 6 kOhm all the way to WOT ??
Or am I missing something ??

Regards
Steven

 

nope, it basically is like a switch to tell the ECU if the throttle is opened or closed. it should read ~4.6Kohms at around 40% throttle.

next step is to double check ignition timing then i would also look at the fuel pressure to see if possibly someone put in an upgraded fuel pump.

 

Thanks,

good to know that its working right.

Fuel pump should be an easy check, but not fuel pressure, dont have the instruments for this.

Timing is on my list too, althought I never did it. Guess with an howto it will work too.

Another question: Can the fuel ratio be adjusted on our cars, so I could lean it out a small bit when I checked the rest ?

Could a clogged cat have an influence on the fuel mixture ?
The O2 sensor has been checked last time it went to a shop.
Although I prefer doing things myself. I have to doublecheck the shops work
to make sure they did it right. That way I might also do it myself, saves me headaches and money.

Sending the injectors off for cleaning would be a nice move. But i dont want to take the uim off and have no car for weeks.
Primaries are a pita to reach.
Cant unbolt the uim on the parking lot.

Regars
Steven

 

definitely sounds like fuel in the crankcase. This is actually common on heavily modified turbo engines experiencing oil dilution from hard driving. It is happened to me multiple times.

Is the crankcase ventilation working?

 

a clogged cat could be a problem but you would notice a severe lack of performance higher in the RPM range.

there really is no way to make more than small adjustments to the fuel system, which is via the variable resistor on the RF strut tower. warm up the car and let it idle down, then adjust the screw counterclockwise until the engine starts to stumble then turn it back about 1/8 turn clockwise. the rest is up to the AFM, injectors, fuel pump and plumbing.

i doubt there is anything wrong with the crank ventilation system, usually the symptoms are the reverse of these.

 

Thanks Karack,

just returned from the compression test.

Results (cold engine):

Front rotor: 110 PSI, 120 PSI (with oil sprayed on the rotor)
Rear rotor: 95 PSI, 115 PSI (with oil sprayed on the rotor)



Remember, first engine with 139000 km (+- 86000 miles) on it.
Measured at the Trailing spark plug holes, with EGI fuse pulled.

I checked the apex seals and rotor faces through the leading spark plug holes with a lcd video borescope.
And turned the engine over by hand.

I have seen lots (!) of carbon buildup on all 6 faces.
When an apex seal passed the plug hole I stopped and could see a tiny movement of the
apex seal when I firmly pushed the engine further.
It is very minimal but its there.

I am now cleaning the plugs which are showing signs of running too rich (dark black)
Of course checked plugs before spraying oil on the rotors
Plugs are sitting now in parts cleaner and waiting to be cleaned.

Any ideas ?

Steven

 

might try a water injection treatment on the engine, there will be a little wobble to the apex seals if you rock the engine back and forth. the 95 psi face would have me a little worried but i also always use the leading plug holes for the compression test(lower spark plugs), remove the EGI fuse, hold the throttle wide open and have the engine fully warmed up during the test for the most accurate results.

the plugs may be a little bit black on the actual faces but the insulator and firing points should be tan to white in color.

 

Thanks Karack,

will do the water injection trick asap. Does this eat the carbon away or will it cause
the carbon coverage to break away ?

After cleaning I put the plugs back and went for a spin, the car was bogging and shaking like
crazy on some rpms. I felt as If I were riding rodeo.
As if there were a hidden rev limiter, rpm needle bouncing back and forth on the following rpms:

First at 3000 rpm, then at 6500 rpm, then 5500 rpm and now at 3000 rpm.
Seems as if the bogging is randomly.

Checked coils, checked for interchanged plug wires - nothing.

Took the cap of the distributor (Yes my car is EU spec so distributor) off and found
that the contact points on the rotor and cap were pretty damaged.
Contact pins were not smooth but had buckles and other irregularitys on.

Did fairly sanded the contacts and the issue went away immediatly, but came back
a while later.

Will order new plugs, new cap and new rotor tomorrow by the local parts dealer.



Any help is greatly appreciated. This 7 is my dd.

Regards
Steven

 

Sounds crazy,but have you tried a thicker oil?

 

thicker oil may also help, if you are using anything less than 10W30. i wouldn't go any thinner on the viscosity than that, the higher the mileage is the thicker the oil should be that you use such as 10W40 year round or even 20W50 in summer if you don't mind a little bit of power loss for additional lubrication.

the water injection breaks up the carbon and sends it out the exhaust. i'm not sure what would cause the bogging issue aside from some of the things you mentioned with the distributor or maybe some water in electrical connectors.

 

Thanks at all

I am currently running castrol edge 10W60, If I find some quality 20W50 at the parts store I will try It out.
I dont want to go below xxW50 as for the summer we get high temperatures here. A pity they dont make any 20W60.


If I can get extra lubrication for a small power loss then count me in !
A/C is removed (as I found out today counting the belts) I havent remarked this until today.

Asked google for a while and I am pretty sure that my distributor and rotor are shot.
PO surely never changed them, and so they look like.

Tomorrow I go to the part store and order my stuff, hope that it fixes my issues.
Want it to run clean before I do an oilchange.

Regards
Steven








PS: My part list so far:

Distributor parts

1x Distributor cap: 24-310B-8245
1x Rotor: 24-303A-8245


Spark plugs:

2x NGK: BUR9EQ
2x NGK: BUR7EQ


Belts:

1x Alternator / Waterpump: 18-381A-8311
1x Airpump: 13-7150-N304
1x Power steering: 15-9090-N326-9U

 

Hell, ordered my parts today and will get them tomorrow.

412 $ (310 €) for the list above, thats one hell of expensive !

But I need my car running asap so I cant wait weeks for stuff to arrive from the states.

Plugs alone were 80 $ (60€)

 

Alright, I have had the same problem with gas in the oil, like a 1/4 of the L to F distance, above F in 2000 miles.

I also have another problem, the car being slower than hell and never see'ing any AFR richer than 14.7 besides idle. S4 Non-turbo car/ECU/injectors with S5 engine/manifolds. Also with a walbro 255. Seeing 18's 19's AFR at WOT.

This has led me to put a little more blame on the side compression seals/oil control rings/and side plate step wear.

I did see the mention of liquid gas as the idea to blame, but regardless of how rich or lean you are, before combustion all the seals have to put up with raw un-ignited gas, until in the combustion phase.

The turbo car did this effect to me first. (you can smell the gas in the oil after around 500 miles on a new oil change) I also found the same answer, of it's near 11 flat AFR, and running 14 psi, of course gas is going to get past those seals. But I don't believe that soo much now.

Also, The rx8 does have an extra seal in between the side compression seal and the outer oil control ring. Not sure 100% what for, but seems would definitely help.

Just my thoughts. Not sure if I'm right at all?

 

Hello,

thanks for all the answers.
So here is an update for so far. Oil level is still climbing very fairly. No codes so far.

Replaced the plugs distributor cap/rotor and changed back the wires to ngk ones and it ran smoother.

Today I cleaned all the contacts on the coils and replaced the High performance coil with the stock unit.

Did a test run and it ran great ! No backfiring and it doesnt shut down on itself when I
put it out of gear. Idle is perfect now. I get 650 to 700 rpm on hot and 1500 rpm cold.
The exhaust sound also changed a lot, no blubbering anymore.
Its amazing

So now I guess its time to get new oil and filter in it. I believe the poor ignition caused fuel
to collect on the sides and slip through the seals.

I scratched the paint on the oil filter with a knife a bit so i will be able to tell if the shop
did put a new filter on it and not just on the bill I know there are some freaky bastards out there.
The new oil will be obvious, new castrol smells so tasty ...
I dont trust shops over the lenght of a nose.

Regards
Steven

 

your car will struggle to run if your wideband was reading 18-19AFRs accurately at WOT. even with a smog pump it shouldn't be higher than about 14.5AFR at WOT/mid to high RPM before your EGTs start to run hot. basically your wideband is faulty or needs to be recalibrated.

fuel going into the crankcase even on non turbo engines without boost pressure is a known issue, usually it is worsened by worn internals such as worn iron side plates that don't seal very well due to excessive step wear but not always, excessive rich conditions will put fuel into the oil.

take that theory and build a motor from all brand new parts and i doubt you will see nearly as much fuel/oil dilution even if the car was running excessively rich, simply because it is sealing better. alternately if the car is running proper AFRs it shouldn't be pushing fuel into the oil even if the engine was rather high in mileage unless it was having issues with flooding during starting.