My idle oil pressure is at around 60 psi. When I rev it to 3000 rpm while the engine is cold, it maxes out at about 100-110 psi. This all looks normal.

I have noticed in the last few hours that my oil pressure is somehow falling with high RPM especially when the engine is warmed up. When I rev the motor, it goes as low as 40 psi. Idle is always normal at around 50-60psi. When I rev the motor, it climbs to maybe 80psi at about 2500rpm then starts to fall at around 3000rpm and continues to fall until 5000rpm+ to minimum of about 30-40psi after which I let go of the accelerator. My initial search seems to indicate crack in the pick-up tube and/or tube gasket/o-ring, but I haven't done anything. I have just about 200miles on the motor. I just changed the filter and oil to 15-50w mobil synthetic. It's the same thing. When it's cold, it's fine, but as it warms up, pressure falls as rev goes up.

Any ideas?

 

How old is the sensor? They fail/read badly, often.

 

I'm using Defi sensor, not OEM sensor.. I wouldn't think a faulty sensor could cause it to read low only at high rpm?

 

faulty is what faulty does

EDIT, to be less cryptic: faulty sensors can cause all kinds of strange readings depending on how they are actually failing

 

You might consider removing the sensor you put on, and screwing in a known good mechanical oil pressure checker (gauge on end of short piece of hose with screw fitting) and verifying that this is really happening.

If it is, then no matter how fresh the engine may be, something is off in there and needs further investigation before it goes dramatically bad.

 

great info. thanks.

I was about to rip open the oil pan to see whether pick up tube was cracked. I'll check with the mech gauge first.

SA3R, I am copying your avatar for my rx8club handle. It sums up how I feel too lol.

 

No problem!

Good luck

 

If you are truly having oil pressure issues you have something WAY wrong with the motor. I've yet to see an oil pickup tube that was cracked, I have seen them with crud (RTV bits) clogging the intake or a huge slab of RTV sealing it to the block that was blocking oil flow.

But, if you're going to go through the pain in the *** of dropping the oil pan, I'd pull the motor and go through things. Could be a failed front cover O-ring or bad oil pump. Pulling the pan and front cover will give you answers, but I would pull the engine to do that.

Again, TEST FIRST to make sure that's the problem with a mechanical gauge. Or get a new OEM sender and use the handy-dandy gauge that's on the dash that works perfectly well.

Dale

 

I spoke with Mazdatrix yesterday, and they say they are 100% sure this is o-ring problem between front cover & the front housing (they even have a nice FAQ article on this very problem on their website). I forgot to mention earlier because I didn't think it was a big deal, but I have D-series 20b with 12A front cover. I'm using 12A front cover mount to mount the 20b engine to the subframe. Mazdatrix said mismatched earlier front cover with late model front housing and my history is most definite for the o-ring issue. It makes perfect sense to me too after reading their FAQ section. For better or worse, I am very convinced that this is the problem I have, so the pan is coming down. I hope pulling the pan can give me a clear view of the oil passage between front housing & cover. If there's a gasket, bulged out o-ring, or gap in it, I know that's the problem. I will report once the pan is completely off, probably this wknd.