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Thread: Engine Code Questions

  1. #1
    12 PSI Boost
    Join Date
    Aug 2018
    Windsor Ontario
    SVO's: 1986 work in progres

    Engine Code Questions

    Got my car running (and yes the new clutch works) but I put the code scanner on and showed the following codes
    1. code 25 knock sensor not detected Is there a way of testing this sensor I know that if its not pinging its not a issue but I want to make sure sensor is ok.
    2. Code 34 I have removed the egr hence the code but is there a issue or problem with removing it?
    3. Code 41 Its says its running lean have a wideband o2 sensor( from Stinger) with stock ecu and a air/fuel gauge that is reading 10.5 which says rich. I have disconnected the temp and cooling fan and installed aftermarket cooling fan should I tie in the original temp sensor wiring so it sends a signal to the ecu . Just guessing at that but im sure someone else has experienced this

  2. #2
    OVER-BOOST!! Bruce's Avatar
    Join Date
    Apr 2003
    SVO's: 86 1E
    Not sure what temp sensor you are referencing as removed. You need the temp sensor in the top of the intake manifold to tell the computer how much fuel you need.

  3. #3
    OVER-BOOST!! GAboySVO's Avatar
    Join Date
    Dec 2002
    Acworth, GA
    SVO's: 2 - 9Ls
    Code 25 is normal as no one i know has been able to perform the throttle blip test to the scanners liking.

    Code 34: The EGR is a smog related device. Waste gas recirulated into the intake has the effect of reducing knock, but it is not required.

    Code 41: Do you have the wide band sending a signal to the ECU or just to the gauge? If not, then that would cause the rich condition as seen on your wide band because its not getting a signal from the O2 sensor.

    The temp gauge sender and fan temp switch do not feed info to the ECU so it has no effect on the AFR. The ECT in the middle of the lower intake does send a signal to the ECU and can affect the fuel requirements.
    Mike S

    '86 SVO 9L Leather
    '86 SVO 9L Road Warrior
    '96 300ZXTT

  4. #4
    OVER-BOOST!! svono50's Avatar
    Join Date
    Apr 2002
    Streamwood, IL
    SVO's: 86 1C
    I think I have had success on the throttle blip test a couple times, but it is certainly rare and ultimately not that important in most situations.

    The analog output on the wideband would need to go to the EEC, while the digital output would go to an appropriate gage from what I have read. My old skool Halmeter uses the factory O2 sensor output, so I am not well versed on the wideband setups.

    There are (3) coolant temp sensors on our engines, 1) EEC temp feed on the top/center of the lower intake, 2) Dash gauge feed on the driver's side of the block and 3) Cooling fan feed on the bottom side of the lower intake facing back toward the driver. Those second (2) locations are from memory, so don't shoot me if I mixed them up.
    86 SVO Mustang
    17 Cooper S Clubman ALL4

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