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Thread: Oil Pressure loss under boost?

  1. #1

    Default Oil Pressure loss under boost?

    Anybody have any thoughts on why I would be seeing an apparent oil pressure loss when going into boost, and comes back to normal under no boost? Engine seems happy, but noticed this reviewing a quick datalog while playing with IEA. Could this be a sensor issue? Not sure how the oil pump would know when engine starts making boost. Engine is twin turbo 403" LS2 in a 4500 lb pickup. Pan holds about 7 quarts oil full. Happens in first 15 seconds of datalog. Global File & datalog attached. Any comments or recommendations on tune would also be appreciated.
    V5 E85 FIC IEA TEST 7-5-18.zip
    Triangle Run 8-2-18.zip

  2. #2
    Join Date
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    Default

    Do you have a vacuum pump on the engine?

  3. #3
    Join Date
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    Default

    Yeah, if it's pulling too much crankcase vacuum at higher RPM (the faster it spins), then it can indicate lower oil pressure.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  4. #4

    Default

    No vacuum pump. I do have crankcase pressure sensor and did not see any excess vacuum. I have two oil pressure sensors, one for the Holley and one for Dakota Digital. Gonna setup Go Pro to watch the Dakota Digital gauge and see if it drops too. Just seems odd it happens right when it starts making boost.

    UPDATE: Dakota Digital gauge did not drop under boost. The sensor for the Dakota Digital is on the oil distribution block to the turbos above the oil filter. Holley sensor is stock LS2 location.

  5. #5
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    Nov 2014
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    Default

    Can you switch the two transducers to see if the oil pressure drop follows the switch?

  6. #6

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    Pretty sure they are different threads, but I will check.

    UPDATE: I couldn't change the sensors, the threads were different. I did change the oil; not sure why, but problem solved!

  7. #7
    Join Date
    Nov 2014
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    Did you use a different type of oil or filter?

  8. #8

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    Same System 1 filter with 35 micron element. Oil is 5W-30 Royal Purple from 10W-30 Royal Purple. Only switched oil type because Walmart was out of 10W-30. It's been pretty hot here in FL. Would have thought thinner oil would have been worse, but it was worth a shot. Only use Royal Purple because it's easier to see on the dipstick with the Purple color.

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