3 different motors, same blow by issue (lots of gas in oil)
09-14-10, 10:59 AM
#127
First off, 5-10% fuel diltuion in these cars is fairly common. What seems to cause it is rich (i.e. low 11s) fuel mixtures being pushed past the oil control rings under boost. Oil "blow-by" and/or insufficient crankcase venting is most likely NOT the primary driver of this problem - this entire thread seems to have side tracked down that rabbit trail, for whatever reason
09-14-10, 04:10 PM
#128
I can assure you that poor crank case ventilation will cause oil coming up your filler neck, i have seen it so many times. Having the incorrect level oil in an engine(i.e too much) will cause oil to come up as well.
If your mixtures are very rich. Dial them back. But your issue is crank case ventilation.
If your mixtures are very rich. Dial them back. But your issue is crank case ventilation.
09-16-10, 10:05 AM
#133
Sure did. I've also just bought 2 1.5" filters and am about to order two 1.5" npt nipples to weld or tap into the oil filler tube and oil cap.
edit: Maybe I should ask this again because maybe it got lost somewhere in the 5 pages of posts. Can improper crank case ventilation cause gas to get into the oil? I don't really have a big problem with oil coming out of the nipple at the top of the oil filler tube. My problem is that I get a ton of gas in the oil. Probably about a quart over within about a week or so of driving.
edit: Maybe I should ask this again because maybe it got lost somewhere in the 5 pages of posts. Can improper crank case ventilation cause gas to get into the oil? I don't really have a big problem with oil coming out of the nipple at the top of the oil filler tube. My problem is that I get a ton of gas in the oil. Probably about a quart over within about a week or so of driving.
Last edited by hondahater; 09-16-10 at 10:17 AM.
09-17-10, 12:21 AM
#134
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Just about every car with a factory turbo runs between 10:1 and 11:1 at WOT, and the newest crop of turbo piston engines are richer than that. But they also run very tight ring gaps and piston-to-wall clearance. Some level of dilution for modified turbo rotaries seems inevitable.
09-21-10, 06:01 PM
#137
This is my breather system.. my Oil pressure stays at 60psi.. Tapped the oil cap,. ran it into breather,. down back into the (2nd?) return in the oil pan from the stock twins.
sorry if this isnt what you are looking for, i just jumped in this and you asking for breather system pictures.
Last edited by Sandrock; 09-21-10 at 06:04 PM.
10-13-10, 05:30 AM
#140
talking head
/\/\ you do realise that up to 91,, engines are supposed to make 70 psi by 3000 rpm
and that FD is a notch higher again
and there is something wrong if above 3000 rpm it can never get to the point where its forcing the reg open at 70 psi
- no matter what was done to the crank jets-
i think you have a rather average gauge,,or some very contaminated fuel and a **** oil pump
---------------------
as for the OP,
and am i correct if i believe its an 850 / 1600 combo on a half or full bridge at 40 psi ( no engine vacuum ) base ?
if so,, what is your normal idle vacuums ?
can you also disclose your staging information please
please tell me you dont have rev stage at 1350 or 1500 rpms and vac stage at -10 or -5 ( inch Hg )
i have suspicions you are staging almost straight off idle ,, and basically running most of the time in post staging
this will amount to basically being nearly always in 4 injector operation,, with extremely poor fidelity due to the injector sizings
mazda intended staged injectors so you could take the first pair out to around 75 % duty with all the fidleity that gives before bringing in the other pair
with 850's it should be 2500- 3000 rpm and around 2 psi ,, before even a bridge runs them short of duty
also,, shift that cruise threshold so that it actually represents a vacuum you will see whilst cruising
if handset 2.5 D tuning
then this should be around -10 inch Hg and the WOT tune threshold should be at -5 inch HG or 0 psi
and that FD is a notch higher again
and there is something wrong if above 3000 rpm it can never get to the point where its forcing the reg open at 70 psi
- no matter what was done to the crank jets-
i think you have a rather average gauge,,or some very contaminated fuel and a **** oil pump
---------------------
as for the OP,
and am i correct if i believe its an 850 / 1600 combo on a half or full bridge at 40 psi ( no engine vacuum ) base ?
if so,, what is your normal idle vacuums ?
can you also disclose your staging information please
please tell me you dont have rev stage at 1350 or 1500 rpms and vac stage at -10 or -5 ( inch Hg )
i have suspicions you are staging almost straight off idle ,, and basically running most of the time in post staging
this will amount to basically being nearly always in 4 injector operation,, with extremely poor fidelity due to the injector sizings
mazda intended staged injectors so you could take the first pair out to around 75 % duty with all the fidleity that gives before bringing in the other pair
with 850's it should be 2500- 3000 rpm and around 2 psi ,, before even a bridge runs them short of duty
also,, shift that cruise threshold so that it actually represents a vacuum you will see whilst cruising
if handset 2.5 D tuning
then this should be around -10 inch Hg and the WOT tune threshold should be at -5 inch HG or 0 psi
10-14-10, 10:28 AM
#141
THanks for the input man I'm going to get all my microtech setting and post them on this page so you can see them and let me know if this is what's going on. I am no tuner so I really can't say for sure what's going on but I know I had my car tuned by kilo in florida but I'm sure he usually tunes for track rather than street. It was running rich at something like 10.5:1 in wide open throttle. But like I said I'll post the tune here. Also you are correct 850cc and 1600cc injectors. with a half bridge.
10-14-10, 03:31 PM
#142
bumpstart. If you want to stage 1700cc injectors are 3000rpm. Go right ahead. Will always be a flat spot. Stage them early and you wont have a flat spot.
10.5:1 is probably alittle rich unless your running 25psi+boost.
Posting your microtech settings here aint going to achieve anything. You need to get your car on the dyno and make sure your cruise settings are dialed in ok with at least 13.5 or leaner afrs in most areas. And on boost dial it back to mid 11s on your higher boost settings and low 12s in low boost areas.
10.5:1 is probably alittle rich unless your running 25psi+boost.
Posting your microtech settings here aint going to achieve anything. You need to get your car on the dyno and make sure your cruise settings are dialed in ok with at least 13.5 or leaner afrs in most areas. And on boost dial it back to mid 11s on your higher boost settings and low 12s in low boost areas.
10-14-10, 03:50 PM
#143
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I think your oil pressure will stay up even with high fuel dilution. Does it smell like gas? You should send it in, it's only $25, and post the result in the "UOA" thread in the third gen section. I have a hard time believing adding a catch can and breather really decreases fuel dilution all that much, but maybe it does....I still think it's blow-by past the oil control rings under high boost and rich mixtures
Last edited by no_more_rice; 10-14-10 at 03:54 PM.
10-14-10, 04:50 PM
#144
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had the same issues till i did this, drilled and tapped the by the oil filler tube for a -8 fitting and ran one from there and the other from the top of the oil filler neck. haven't had a problem since. i would have atleast a quart or two overfull in the sump from dilution within 1000 miles
http://forums.vwvortex.com/showthread.php?4360709
http://forums.vwvortex.com/showthread.php?4360709
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