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S14B20 O2 sensor

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  • S14B20 O2 sensor

    Hi everyone!

    I have a 320is, and the s14b20 doesn't hav an o2 sensor. My car have a rich mixture and i can't approve the anual revision. I know there's a switch in the ECU that let me adjust the ignition and fuel in the combustion called FQS (Fuel quality switch). I'm affraid to move the switch and get a lean mixture. Could be an o2 sensor installed with a wideband to set a correct ratio? could be added to the standard ECU the original S14b23 O2 sensor? another suggestion ?

    Regards!
    Juan

  • #2
    Hi Juan,
    I think probably the best first step is to check the tuning and address any known issues just go through everything, absolute last thing would be adjust the FQS switch position in the DME.
    Think of it this way it would have been good when new and now it is older it is not so good, start with the basics check valve clearance then compressions, plug leads , plugs, cylinder head to exhaust studs for being tight, intake gaskets, check throttle sync and clean the throttle air bypass screws.

    Replace the water temp sender for the DME

    Hope that may help
    Dave.


    E30 M3 1987
    Mini Clubman GT
    BMW E36 323 Msport
    Toyota Corona
    KTM 200EXC
    Honda CB50 (1979)

    Comment


    • #3
      Thanks Dave!

      I already have cleaned the throttle bodyes, check de AFM, replace the fuel pressure regulator, repair the ICV, replace the transistors at the DME, cheked the throttle switch, adjust camshaft position and the car seems to have the ignition unsyncronized and a rich mixture.

      The water temp sensor still original. I can change it.

      My point is that the car have no feedback from the output, i don't have that feedback too and i don't want to make a hole in a piston :P. That's why i'm asking if there's a simple way to add an O2 sensor to the original DME or another solution to avoide this.

      Thanks again!

      Comment


      • #4
        Hi Juan, Dave is correct, something is not to spec. Have you checked the intake vacuum (300mBar or 22.5 cmHg) and idle ( steady at 850rpm)? I suspect you have a vacuum leak. It is not a simple matter to wire in a O2 sensor. Your ECU data Eprom would need to be changed to one which used an O2 sensor. The 320is was only available in Europe so you are limited to a source of a new ECU (087) or at the least a data Eprom. A competent mechanic with a CO analyser should be able to use the readings to diagnosis where your problem is.

        Keep us posted.

        Comment


        • #5
          I would fit a wideband o2 sensor and gauge, work out where your engine is too rich or too lean, rectify and get the annual approval.

          Converting your dme and wiring harness to closed loop like a us
          ​​​ spec car would be too involved. It could be done I guess but a headache. You would need to adjust the dme to s14b20 specs also somehow...

          Comment


          • #6
            Has she passed the annual inspection last year? What level of CO (carbon monoxide) must you stay below of at idle during the inspection?
            What level do you get at what rpm?

            A vacuum leak would lean the mixture on an engine without lambda control whilst the OP is trying to remedy a rich running engine...

            I have a 320is and fitted a cat and closed loop lambda control. It requires the addition of the wires to the oxygen sensor and one extra to replicate the blue and black connectors that the M3 has in order to run open or closed loop. No change of eprom required but it is a must to keep using 98 RON or higher octane fuel.

            Too rich can be caused by
            -a faulty (the blue one) coolant temp sensor or its wiring (~200 Ohm it should read at engine operating temp)
            -leaking injectors
            -fuel pressure too high due to faulty pressure regulator
            -ignition dropping out and fuel only burns partially in the hot exhaust. --> is this what you mean by ignition unsynchronised?

            How have you checked the afm?

            A rich mixture won't burn a hole in the piston, only a lean mixture will. Since you say you have a rich mixture but are afraid of damaging a piston I wonder if you might be using the rich and lean the wrong way around?

            That's 6 questions for you in order to assist you in solving your problem.
            Answer all six and I'll be back to try and help you to solve this.

            Comment


            • #7
              Good info hardtailer

              Comment


              • #8
                Originally posted by jwbavalon View Post
                Hi Juan, Dave is correct, something is not to spec. Have you checked the intake vacuum (300mBar or 22.5 cmHg) and idle ( steady at 850rpm)? I suspect you have a vacuum leak. It is not a simple matter to wire in a O2 sensor. Your ECU data Eprom would need to be changed to one which used an O2 sensor. The 320is was only available in Europe so you are limited to a source of a new ECU (087) or at the least a data Eprom. A competent mechanic with a CO analyser should be able to use the readings to diagnosis where your problem is.

                Keep us posted.
                Hi jwbavalon. I don't have the tool to check the intake vacuum. It's a thing to review in the car. The Idle stay at 900 rpm. I think there isn't a leak because the engine would be accelerate by itself.



                Comment


                • #9
                  Originally posted by hardtailer View Post
                  Has she passed the annual inspection last year? What level of CO (carbon monoxide) must you stay below of at idle during the inspection?
                  What level do you get at what rpm?

                  A vacuum leak would lean the mixture on an engine without lambda control whilst the OP is trying to remedy a rich running engine...

                  I have a 320is and fitted a cat and closed loop lambda control. It requires the addition of the wires to the oxygen sensor and one extra to replicate the blue and black connectors that the M3 has in order to run open or closed loop. No change of eprom required but it is a must to keep using 98 RON or higher octane fuel.

                  Too rich can be caused by
                  -a faulty (the blue one) coolant temp sensor or its wiring (~200 Ohm it should read at engine operating temp)
                  -leaking injectors
                  -fuel pressure too high due to faulty pressure regulator
                  -ignition dropping out and fuel only burns partially in the hot exhaust. --> is this what you mean by ignition unsynchronised?

                  How have you checked the afm?

                  A rich mixture won't burn a hole in the piston, only a lean mixture will. Since you say you have a rich mixture but are afraid of damaging a piston I wonder if you might be using the rich and lean the wrong way around?

                  That's 6 questions for you in order to assist you in solving your problem.
                  Answer all six and I'll be back to try and help you to solve this.
                  Hi hardtailer!. Great info! So, adding an O2 sensor seems very simple!. Do you use the M3 o2 sensor or a generic bosch?
                  - I'm waiting to arrive the new coolant temp sensor.
                  - The injectors was controlled and all is fine.
                  - The fuel pressure regultator is new.
                  - I think the spark is a little before that had to be. So if i could correct the spark time may i have more fuel detonated.
                  - AFM was checked and it's ok!

                  My car have a rich mixture. I'm affraid to get a lean mixture by correcting the spark and set less fuel and by consecuence make a hole in a piston :P

                  Thanks again!

                  Comment


                  • #10
                    Generic bosch 3-wire lambda sensor will do.

                    I'll ask again as you didn't answer the question only repeated the result:
                    How have you checked the afm?
                    Ask the workshop how they did it if you didn't do it yourself.

                    You didn't answer:
                    Has she passed the annual inspection last year? What level of CO (carbon monoxide) must you stay below of at idle during the inspection?
                    What level do you get at what rpm?

                    'I don't know' is an acceptable answer, no answer I find insulting as the effort I put into this is greater than the effort you are obviously willing to put into solving your (not my) problem.


                    Comment


                    • #11
                      Hi Hardtailer.

                      Sorry for th inconvenience. I didn't understand your question about AFM. I sent it to an especialist to clean the tracks and check the impedance . I don't know how many but he said that have the correct values. i'll ask to him.

                      I missed up to answer your question about CO and HC levels. I'm from Argentina and the revision it's a joke...they have a few sites to do the revision but the have different read values. I have passed before the anual revision and now i'm not. The values are:

                      - GASES : CONTAMINATION LEVEL TOO HIGH CO AT IDLE: (4,29);% CO. OTROS: (415,00); PPM HC, (9,45);% CO2

                      - GASES :CONTAMINATION LEVEL TOO HIGH HC AT IDLE: (415,00); PPM HC. OTROS: (4,29);% CO, (9,45);% CO2

                      - GASES : CONTAMINATION LEVEL TOO HIGH CO AT 2500RPM: (3,22)% CO. OTROS: (383,00) PPM HC, (7,07)% CO2

                      I'm not sure but i think the CO is 2% and the HC is 650 ppm (and i can't understand why i have an observation).

                      Thanks again and sorry for the inconvenience.

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