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high oil pressure, knock sensor codes, flat spot in accelera

This is a discussion on high oil pressure, knock sensor codes, flat spot in accelera within the General Help forums, part of the LSx Technical Help Section category; i have been battling a knock sensor low voltage code for a few weeks now. gave my car to the ...

  1. #1
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    high oil pressure, knock sensor codes, flat spot in accelera

    i have been battling a knock sensor low voltage code for a few weeks now. gave my car to the ship i go to to replace the sensors and the whip. all ohmed out good yet the codes still come in

    so i replaced my Throttle Position Sensor yesterday (the old one has no spring return and it is all jumpy on the ohm meter so i figured it was shot) from an idea form a buddy, and the car ran normal, no codes, oil pressure was normal. prier to replacing the Throttle Position Sensor replaced and this morning i fire it up and i get a knock sensor 1 low voltage code a few miles down the road, and my oil pressure is running high. ( normal 40 at idle and 55 WOT, high is 55 at idle and 65-75 at WOT. i re-calibrate the Throttle positioning sensor ( unplug it and turn the key to run without starting the car for 30 sec, turn off the key and plug the Throttle Position Sensor back in) the car is back to normal, no codes and normal oil pressure. i can see on my tuner that it is at .39% throttle at idle and it is reading 0 in the mornings before i touch it. it throws the codes above.

    i have had my knock sensors replaced along with the wiring twice, ohmed it all out and checked both knock sensors are working properly. and the ac signals seem to be getting to the ECM as they should be

    the last piece in the puzzle would be a ECM right?.

    i just cant find a connection between my oil pressure, knock sensors and the flat spot in my acceleration and how the TPS replcement fixes them all. and why i have to re-caliberate the sensor everyday i go to drive my car.

    fyi i do have the diablo sport tune in the car along with 3.73 rear which is corected with the tuner. its the same issues weather i put the factory tune or the diablo one in the car.

    sorry for jumping around but thanks for any ideas you all have?.
    Last edited by Stephen Thiede; 11-25-2014 at 08:23 AM.

  2. #2
    Spaz is My Mentor SMWS6TA's Avatar
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    Sounds like you have a wire harness issue. Who replaced the knock sensors, you or a shop?

    It's very easy to pinch the wire harness if in a hurry.

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    the shop did the first time. i did the 2nd.

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    Spaz is My Mentor SMWS6TA's Avatar
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    Regarding the knock sensor it's easy to break, they are in a very bad location. So it's possible the OPSU might need replacing.

    I would trace all the wires from the TPS & IAC back to the the ECM as well as the KS wires to make sure they aren't pinched or cut.

    Once you know that then you can move on to other checks. It may mean taking a voltage reader and check the wires from the ECM to the sensor.

    I do not envy you, electronic gremlins are a bitch to find.

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    sry but opsu? iac?

    i got the other ones lol

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    Spaz is My Mentor SMWS6TA's Avatar
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    OPSU - Oil Pressure Sending Unit - Located on drivers side behind the intake.
    IAC -Idle Air Control Sensor - Located above the TPS. I say check this one because it's in the same wire loom as the TPS



    When's the last time you cleaned your MAF sensor?

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    havnt cleaned it since last year i think.

    the opsu was replaced last month to see if that was my high oil pressure problem. same reading with the old one and the new one.

    i will order a iac tonight with a can of MAF cleaner.

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    Spaz is My Mentor SMWS6TA's Avatar
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    no need to order the IAC yet. Like I said it looks like a wire loom issue.


    BTW when you say idle, what rpm? Also what is the high reading rpms? I ask because the oil pressure readings look normal to me.

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    normal 40 at idle and 55 WOT, high is 55 at idle and 65-75 at WOT

    idle is around 700-800

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    Strange sounding issue. How about a ground wire that was missed or broken somewhere along the way?

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    i didnt see any grounds that were loose or disconnected. ill have to go thru my engine bay again and see.

    next time its warn out. we are looking at a but of snow for the holiday. is there a ground guild to the various ground points in the engine bay that i can reference so i dont miss any?

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    Spaz is My Mentor SMWS6TA's Avatar
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    there are 1 on the passenger side cylinder head and 2 on the drivers side, all in the back. It's possible one got broke but not sure how.

    It could be a bent/broken pin in a connector or ecm. Like I said electrical gremlins suck.


    What oil weight are you using?

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    I once pulled a single wire out of the wire harness itself that leads back to the MAP sensor and OPS. The harness and wires looked good, but just a slight tug on the wires while holding the black connector is how i found the problem. The connector i am speaking off is located to the left of the intake and throttle body when looking at the engine. May not be your problem, but I bet you have a simular issue. The wires inside the connector itself will make just enough contact to not show up until they vibrate around while the engine is running or driving around. Of course I realize all this AFTER replacing the stupid MAP sensor. Which is also a fun thing to do! LOL

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    yea i will be checking the grounds and the harness once the snow melts. we got 6 inches today. prob this weekend.

    ill let you guys know what i find.

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