erradic oil pressure?

[shagwag]

first of all if this is in the wrong place, sorry.

i was coming home from the dyno and out of nowhere my oil pressure gauge drops to 0 (stri x line gauge if that matters)
obviously i flipped out and shut off the engine and coasted off the highway. anyway i later discovered that the gauge reads pressure when the car is cold and when im above 2.5/3.5k rpms depending on temp. my idiot oil light does not come on when the gauge reads 0. i have actually been driving it around and no problems yet. so is it the cheapo oil pressure sender or is there some crazy oil pickup disaster in the making?

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[xIceHoundx]

Ive had similar problems lately, ive got glowshift gauges(came on the car) and ive seen it jump high and drop to 0 before but no oil light or engine code. I've been told by another subbie owner that using oil pressure gauges isnt very reliable because it bounces around so much on subarus and I would like to get my facts straight on oil pressure. Ive got a 2004 Impreza STi built engine

[KillerBMotorsport]

You want facts, we've got facts

Here are the factory specs...



Anytime there's an oil pressure issue take caution. It could be as simple as the sending unit/ gauge, a wiring problem or something more serious. If I were in your shoes I'd get a mechanical gauge and screw it into the OEM sensor location. Any shop should be able to perform this test too. If you have presure then it's a gauge/sender/wiring problem, if not TURN THE CAR OFF and check the oil level, pickup, pump, etc...

[xIceHoundx]

Thanks

[wrxwhat]

I have the STRi DSD gauge and my piece of **** gauge/sender does the same thing.... Usually drops to 0 after I've been cruising on the highway a while (200+ miles)

[KillerBMotorsport]

The senders can be ground sensitive. Tighten in town a wee bit more and see if the symptoms change.

[xIceHoundx]

To give you a better idea of my situation here is my mods list under the hood:
Engine:
-Agency Power Billet Pitch Stop
-APS Tumbler Valve Delete Assemblies
-Cobb Stage 1 Tuner Series Block
-Cobb Stage 2 Heads
-Cosworth Timing Belt Guide
-Cosworth Head Gasket
-Cosworth Subaru WRX STI EJ25 AVCS Cams
-Cosworth Subaru EJ20/25 Engine 2002-06 Modified Oil Pump
-Gates Racing Timing Belt
-Group N STi Engine Motor Mounts
-Group N Upgraded Transmission Mount
-NGK One Step Colder Iridium Spark Plugs
-Perrin Lightened Crank Pulley
-Fumoto Oil Drain Valve

Forced Induction, Intake, and Exhaust:
-APS Dual Vent FMIC Blow Off Valve Kit
-Cobb Tuning SF Intake
-Invidia G200 Titanium Tip Catback Exhaust
-Kartboy Exhaust Hangers
-Perrin Equal Length Header
-6SR/generic FMIC with upgraded red coated Perrin hot side pipes
-Perrin Rotated Mount GT3076R .82AR Turbo Kit
-Thermo-Tec Cool Tube Air Intake Heat Shield

Cooling:
-APR Carbon Fiber Radiator Shroud
-Nitrous Express N-tercooler Sprayer Kit
-Perrin Radiator Hose Kit
-PWR High Performance Radiator
-STi Radiator Cap Radiator Cap (1.3 Bar)
-Zerosports Thermostat
- Perrin Coolant Overflow Tank




Fuel System:
-Perrin Fuel Rail Kit
-Power Enterprise 850cc Injectors
-Walbro 255 LPH Fuel Pump & Install Kit

Engine Management and Electronics:
-Cobb Tuning AccessPort V2
-GlowShift 52mm Elite 7 Color 30psi Boost/Vacuum Gauge
-GlowShift 52mm Elite 7 Color Oil Pressure Gauge
-GlowShift 52mm Elite 7 Color Volt Gauge
-GlowShift Gray Triple 52mm Gauge Pillar Pod
-HKS CAMP CPU and Junction Box
-HKS CAMP EGT Sensor and Harness
-HKS CAMP Boost Sensor and Harness
-Optima Red Top Battery
-Perrin EBCS Universal Electronic Boost Solenoid
-PLX Devices R-500 Wideband Computer Kit w/EGT

Drivetrain:
-ACT Streetlite Flywheel
-ACT Street Disc Clutch Kit
-Kartboy Short Shifter and Bushings Combo
-Perrin Performance Shift Knob
-Techna-Fit Stainless Steel Clutch Line

The chassis has just over 40k miles and the engine has somewhere around 10k, it has a Cosworth Subaru EJ20/25 Engine 2002-06 Modified Oil Pump, I assume that would make my oil pressure read off pretty high? I dont have too much faith in the gauge as it not long ago was flickering and cutting off completely but now is back to always staying on, but its usually reading somewhere between 100-120psi, from time to time around 80psi.

Another thing ive noticed and believe is unrelated to the oil system is a ticking heard from the engine that I believe is valves and rockers. Im assuming its just a gap between the two that needs to be closed, but if anything has any ideas please let me know as im new to subaru and their engines.

[scby rex]

I think its just the cheap made in taiwan sender stri uses.

[ScoobyAficionado]

Interesting! Does anyone have that spec sheet for one of the newer Subarus with the 11mm pump?

[john 1badSTI]

yes I have a sheet with all the pumps listed--the 11mm pump relief valve is set to pop off at 78psi oil pressure at 6000 rpm is supposed to be 56.8 psi and 14psi at 600 rpm. I hope this helps.

[jaybirde978]

I had a glow sport elecric sender in which the sender passage was improperly drilled ,I had exact same issues your experiencing ,I removed it, finished drilling it ,Since then it has performed flawlessly...I do notice a fluxuation when the alternator has a large demand on it ,being a electronic sender I assume the alternator winding is causing issue whith the winding in the sensor.I hope this helps also ,simple truth teller, hook up a tee & use a manual handheld psi gauge to calibrate your readings

Jay

[ScoobyAficionado]

Originally Posted by john 1badSTI

yes I have a sheet with all the pumps listed--the 11mm pump relief valve is set to pop off at 78psi oil pressure at 6000 rpm is supposed to be 56.8 psi and 14psi at 600 rpm. I hope this helps.

Thanks! It's actually more the flow # that I'm looking for to compare with the 10mm pump at 5000rpm.

P.S.: DeFi oil pressure gauge: No problems after 6 years.

[CKxx]

I'd grab a non-POS gauge before I did anything else.

[john 1badSTI]

Originally Posted by ScoobyAficionado

Thanks! It's actually more the flow # that I'm looking for to compare with the 10mm pump at 5000rpm.

P.S.: DeFi oil pressure gauge: No problems after 6 years.

the flow of 11mm pump-6.4l/min at 600rpm,63l/min at 6000---10mm-4.6l/min@600,47 l/min@6000. and defi is all I run even though they are more expensive but my motto is you get what you pay for.

[ScoobyAficionado]

Thanks... are you sure that's 63L at 6000rpm on the 11mm? The 10mm above says it's 47L at 5000?

Just checking. Wouldn't want any half-truths on da internetz. Maybe they changed the RPM statement with model years.

[john 1badSTI]

The sheet I am getting my info from is straight from subaru and lists all info on the 9mm,10mm,11mm,and 12mm pumps.and yes it is 63l@6000 and for some reason they do rate the 10mm at 47l@5000 and 6000 rpm on the sheet.

[ScoobyAficionado]

Thanks for clarifying John!

Ahem... could I trouble you for 12mm too? I lost a motor in a long corner with a 12mm oil pump and a stock oil pan and I'm trying to measure just how stupid I really was.

[john 1badSTI]

sure here they are--6.5l/min@600rpm 59l/min@6000rpm 14psi@600rpm 85psi@6000rpm relief valve set at 85 psi.Chances are with the stock pan and hi volume of the 12mm pump you sucked the pan dry and starved a bearing.

[shagwag]

soooo. i bought a new sender meant only for vdo gauges. turns out they mean it. my pressure read backwards it would idle at "80" and drop to "40" at higher rpm's. heheh anyway it was a pos sender. are "stack" brand gauges any good. im looking at the electronic 52mm oil press gauge for a 100 bucks. they have dsd ones for 250 but thats a bit steep for a glorified autometer.

[ScoobyAficionado]

Originally Posted by john 1badSTI

sure here they are--6.5l/min@600rpm 59l/min@6000rpm 14psi@600rpm 85psi@6000rpm relief valve set at 85 psi.Chances are with the stock pan and hi volume of the 12mm pump you sucked the pan dry and starved a bearing.

Yes, that's what the theory has always been. My second built motor had a 7qt oil pan. It's for sale, BTW, since it won't fit a Twinscroll setup.

Anyone else find it odd that the 11mm pump increases flow by 16L, then the 12mm upgrade drops that flow by 4L?

Typical Subaru errors in it's documentation?