High oil pressure w/ 3rd cylinder misfire
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This is a discussion on High oil pressure w/ 3rd cylinder misfire within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; First off, I am new to subaru's so bear with me. I have an 03 wrx that came with a ...

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    High oil pressure w/ 3rd cylinder misfire

    First off, I am new to subaru's so bear with me. I have an 03 wrx that came with a stage 2 map with only stage 2 clutch and exhaust. Recently the check engine light came on and the oil pressure, normally running at 70 psi while running and 25 psi idle, went to 100. Went away but checked the code and said 3rd cylinder misfire. replaced the spark plugs and oil pressure still would not fall below 100 even after running. Got oil replaced and ecu reset to stock, but I'm still hearing a whining noise coming from near up under the hood (checked the brakes, wheels, and axels as other threads have recommended). Going to check the FPR hose tomorrow, but engine pressure is still at 100 in idle and drops to 80 when warm and 40 at idle, but still runs to 100 randomly. Is this healthy or wtf is going on? not to mention i miss not going above 5 psi boost anymore so the sooner i get this fixed the sooner i get this mapped. please help

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    OMG WTF MainFrame's Avatar
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    Where is the pressure sending unit attached? Is the gauge mechanical, or electrical? A bad ground in my electrical oil pressure gauge sending unit would cause it to read higher than normal. It would make more sense that the gauge is reading wrong than the oil pressure suddenly rising. The oil pump turns with the rotation of the engine, so it can't be spinning any faster than it was before. I suppose there could be something in it clogging the bypass, but the oil only bypasses at 90psi and above, so even if the bypass is shut the pressure should still go down to ~20psi at idle.

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    The guage is electrical, not sure where the sending unit is attatched. I'll check the bypass when i get off work tonight, that could be the problem since it isnt bypassing after 90 and not dropping to 20 psi at idle, i'm either sitting at 30 or 40 in idle then go to 80 to 90 running, hitting 100 in 3rd, drops to 90 in 4th, then back to 100 in 5th. slowing down from 5th it does sound like it's not releasing pressure like it should be. Thanks for the advice mainframe, gonna try and see if i have a bad ground then move on to the sending unit

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    OMG WTF MainFrame's Avatar
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    How are you planning on checking the bypass valve? If you're going to go to the trouble of pulling your oil pump off you might as well replace it.

    30-40 at idle and 80-90 running won't be a problem. Oil pressure shouldn't have anything to do with what gear you're in, it's solely RPM dependent. You could just sit in neutral and free rev to see what pressures you're hitting at what RPM. You should be hitting 90psi near redline, and 30 or 40 psi at warm idle isn't going to hurt anything.

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    90s not bothering me. it's the 100 when i'm running warm and rpms arent effecting the oil pressure and it's just rising on it's own or sitting at 100. so ur probably right, i'll have to replace the pump and my buddy will be coming over tomorrow or monday to help me with that. i'll let you know how it goes. thanks for the help

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    OMG WTF MainFrame's Avatar
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    Before doing all that I would at least pickup a $20 mechanical gauge from Autozone to double check your readings. If it reads the same then go ahead with the new pump.. probably wouldn't be a bad idea to flush the engine while you're at it.

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    haha yeah, i'm just paranoid as hell right now and my minds jumping all over. tomorrow i'll be testing the wires and hopefully it'll just be a switch or a bad wire or 1 of a 100 other small things that don't require any work to the timing belt. not to mention a diagnostic is a whole lot cheaper before jumping to replacing my oil pump

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    faulty sending unit (car came with electrical gauges). I will be replacing these tomorrow

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    OMG WTF MainFrame's Avatar
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    Bingo! Glad to hear it's just the gauge.



    I have Prosport gauges and I have had to replace my oil pressure sending unit three times already (and now it's starting to act funky again).

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    ironically it started working again, but it's definitely faulty so i'm going with this... Auto Meter 2422 - Auto Meter Traditional Chrome Analog Gauges - Overview - SummitRacing.com

    No power supply, all chord. When i'm not close to broke i'll change it to braided steel cable. And the only reason why i say it's faulty is because it's telling me about 20 psi higher than i'm actually reading at times and even though it kicked back in and started working again, it still reads high up to 90 in 4th, but then again this may be normal without my previous stage 2 map, which i'm still pretty unhappy about losing.
    And i'll say this about pro-sport; the sending unit definitely seems unreliable so if you go with the performance series and get the oil pressure conversion plate you can still use prosports if you like them, but ur getting direct oil pressure from the filter (another model comes with dual water/oil temp but whatever) from that conversion plate. However u still have to attach 3 power chords for lighting to ur inner fuse box *thumbs down* just some research i did

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    and re-reading that i meant oil FILTER conversion plate with dual water/ oil PRESSURE outputs

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    damn, it's still a third cylinder misfire and thats what i'm hearing whining sometimes, though the electrical sensor is definitely lagging. looking forward to my new gauge and heading over to the misfire thread

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