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Thread: faulty lambda control

  1. #1
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    faulty lambda control

    In an attempt to reset my base air/fuel mixture I noticed a loud buzz if the Lambda control is hooked up, has anyone else encountered this? Does anyone know of any testing procedures? Thanks

  2. #2
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    The Buzz is the Frequency Control Module and starts buzzing when the fuel pump socket is jumpered, if it did not buzz you'd have a problem . See FAQ's to reset and fine tune Air Fuel Mixture-- excerpt "Re-Adjust Base Mixture Setting
    If you’ve done major fuel system work such as swapping fuel distributor, AFM, WUR, fixed major vacuum leaks or have a non-running car it may be a good idea to re-set your base mixture setting to correct a grossly misadjusted mixture. To do this, jumper the fuel pump. Turn the mixture screw clockwise (rich) until you hear the injectors start to spray. They will make an audible squeel/humming noise. Back off counter clockwise (lean) till they stop, then back off another 1/8 turn. This should get the mixture setting close enough for the car to at least run assuming there are no other problems." --Fine Tuning Mixture Setting---ect.

    <strong>


    Randy
    Last edited by 320iAman; 06-11-2018 at 10:06 AM.

  3. #3
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    If the engine runs, no need to set the 'base mix'. Just fine tune it when the engine is warmed up. For the non-lambda, there's a 'finger in the tail-pipe' test, revealing a small amount of black soot is good after a drive around the block. For the lambda equipped, there's an o2 sensor voltage test - maybe Randy can elaborate on that for you
    Tbd

  4. #4
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    Covered in the Video and FAQ's...

    Randy

  5. #5
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    Need to clarify, I was following the procedure in FAQ to reset base mixture. Car currently does not run. I am trying to get it to run with the Lambda control as it has not been hooked up in years although it had been running since then. Car has sat for the past winter. I was wondering if anyone has ever dealt with that going bad. Thanks for the replies

  6. #6
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    If it buzzes when fuel pump socket is jumpered its good, these rarely go bad.

    From Faq's

    3 - Adjust by Frequency Valve Duty Cycle
    You can also back probe the frequency valve with a dwell meter with the motor running and with the O2 sensor plugged in. With a dwell meter you can read the duty cycle of the valve, you target value is 45 degrees.

    Dwell Meter degrees to Duty Cycle %

    Dwell meter angle measurement / ( 360/ No of Cylinders)

    Example

    45 /(360/4)= 45 /90 = 50% Duty Cycle

    45 Degree Angle = 50% Duty Cycle

    For Dwell Meters and Multimeters with Duty Cycle %

    Randy
    Last edited by 320iAman; 06-12-2018 at 10:25 AM.

  7. #7
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    Thanks Randy ^

    Quote Originally Posted by jayona View Post
    Need to clarify, I was following the procedure in FAQ to reset base mixture. Car currently does not run. I am trying to get it to run with the Lambda control as it has not been hooked up in years although it had been running since then. Car has sat for the past winter. I was wondering if anyone has ever dealt with that going bad. Thanks for the replies
    I've only heard of bad wires at the frequency valve, bad ground wire for the lambda and bad o2 sensor causing trouble with the Lambda unit. Not trouble with the Lambda itself. The fuel pump relay energizes the lambda relay - so that has to be working too, of course.

    Have you done any other tests with the fuel system, checked for vacuum leaks, etc?

    Here's a pdf file, electric manual for your '82. save a copy...

    1981-1983
    http://www.findmymerchant.com/images..._1981-1983.pdf
    Last edited by epmedia; 06-12-2018 at 05:50 PM.
    Tbd

  8. #8
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    Thanks for the collective input. Car currently is not running so probing the frequency valve is not possible. All vacuum lines are new but have been double checked with starter fluid. Vehicle has spark and fuel and it ran before I put it away for the winter. At that time I replaced a couple vacuum lines, bought a new coil but it was still able to start, just harder as temperatures dropped. That was 5 months ago, thought I could fiddle with the fuel mixture and get it to start but I could not. That is when I decided to readjust to base mixture(and reattach Lambda control), in doing so I came upon this noise. As soon as I unplug the Lambda control it stops. My first thought was a faulty computer but didn't think to identify where the noise was coming from. It's possible its the frequency valve, sounds different without the engine running. Either way, with the the Lambda control hooked up or not car does not start. It had been running for 6 years without the control hooked up as it was disconnected by a BMW mechanic that said it was possibly faulty. Car was running rough at the time and I took it to a large BMW shop in Broomfield where this guy worked (and was greatly respected). Got the car back and never hooked the Lambda system back up. I've got a fuel pressure gauge on order.

  9. #9
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    With the Frequency Modulation Valve running with the Fuel pump jumpered, this leaves it out as it is good. My next thought would be the lambda relay, I'd change this out or test it. Too test it see post #11 .when the circuit is complete you'd hear an audible "Click",, if you dont want to test buy one they are $8-12 on ebay ect.

    The top part of this is how 80-83 are wired,,bottom is my upgrade or Hella upgrade.. One can see that the fuel pump relay when energized turns on the Lambda Relay and not vice versa.

    IMG-5_page1_image1.jpg

    Lambda Relay Bosch 0332019151( 5 male spade terminals) and is listed wrong usually as fuel pump relay..Ebay has them and so forth. The FMV is a Solenoid Valve. [S/V] in the diagram. Keep truckin on this you'll get it running. A few clicks of your mouse and diagram get enlarged to huge. Bosch Relay 0332019109 is recommended.

    Randy
    Last edited by 320iAman; 07-04-2018 at 01:39 AM. Reason: Got rid of example and put in actual

  10. #10
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    Once again, thanks for all the thoughtful info. This forum continues to amaze me with all the helpful and talented minds. I will test/swap the relay this weekend

    "The top part of this is how 80-83 are wired,,bottom is my upgrade or Hella upgrade.. One can see that the fuel pump relay when energized turns on the Lambda Relay and not vice versa." - impressive


  11. #11
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    Okay a little update the lambda relay in the diagram I drew, to test this relay the pins 85 and 86 are hooked up to 12 volt source and as soon as the circuit is complete by connection to either pin an audible click can be heard if the relay is good. Its very remote that the connection of 30 to 87-87 would not be good--this connection is the audible click heard when the little spring loaded bar snaps down or the points click together making the 30-87-87 connection. the pin numbers are on the back side next to the pins for easier identification and a little relay circuit diagram is on the side.

    I just tested the same relay we discussing 86 is ground(- batt pole) and 85(+ batt pole) and is power and got my spare relay to click, click, click, this relay uses a diode with forward bias from 85 to 86. This is Bosch 0332019019 , 0332019012 is forward biased reverse of 0332019019.

    On regular Bosch relay without diode protection- 0332019151 test 85 -,gnd,, 86 +, power is used to test it for click,click click.

    the diagram above is good

    Randy
    Last edited by 320iAman; 06-20-2018 at 11:14 PM.

  12. #12
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    It's pumping fuel and getting spark?
    Does any fuel squirt out the cold start injector when the the starter-motor is turning?
    Are the spark plugs wet with fuel/oil?
    Does the exhaust tail-pipe smell like gasoline after a few failed start attempts?

    Is the car still equipped with the original cloth braided hoses on the suction side of the external fuel pump? If so, they must be replaced because sucking air bubbles and possibly seeping some fuel. * if you have to replace these 3 pieces of hose (connected to the metal "Y" fitting), I highly suggest you put the 3mm allen-head fuel-mix-adjust-screw back to it's original setting before trying to start the engine.

    Be careful not to flood the engine with fuel, it's very easy to flood if you're not familiar with behavior of the k-jet system.
    Last edited by epmedia; 06-15-2018 at 06:45 PM.
    Tbd

  13. #13
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    Quote Originally Posted by epmedia View Post
    It's pumping fuel and getting spark?
    Does any fuel squirt out the cold start injector when the the starter-motor is turning?
    Are the spark plugs wet with fuel/oil?
    Does the exhaust tail-pipe smell like gasoline after a few failed start attempts?

    Is the car still equipped with the original cloth braided hoses on the suction side of the external fuel pump? If so, they must be replaced because sucking air bubbles and possibly seeping some fuel. * if you have to replace these 3 pieces of hose (connected to the metal "Y" fitting), I highly suggest you put the 3mm allen-head fuel-mix-adjust-screw back to it's original setting before trying to start the engine.

    Be careful not to flood the engine with fuel, it's very easy to flood if you're not familiar with behavior of the k-jet system.
    Thanks Epmedia, I have seen you offer up this advice enough times that I did it about two years ago, definitely needed it. Car is getting spark and fuel and was starting/running in November but as it got colder it got progressively harder to start. I'm fairly confident I can get it running without the Lambda Control hooked up but don't want to run without it anymore. I was wondering how the Cold Start Valve (as well as WUR, Frequency Valve, Idle Air) function without the Lambda input. I have always assumed it was running rich just to compensate. Never had problems with hot or cold starts before last winter unless it sat for days and even then issues were negligible. As for checking the cold start, plugs and tailpipe, I have not. Just got my fuel pressure gauge today so I plan on properly testing all fuel related components as soon as I am not swamped at work.

  14. #14
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    Basically the Cold Start Valve operates when the starter is engaged as its on the same line and shuts off when the key is not in the start position. The frequency valve will not run when the O2 sensor is disconnected as it runs when the ECU gets certain input from the O2 sensor after warm up and more fuel is required due to too much air in the exhaust detected by the O2 sensor.

    The Wur is independent of the O2 sensor its on the fuel pump relay circuit.

    Randy
    Last edited by 320iAman; 06-16-2018 at 12:53 AM.

  15. #15
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    First video is with Lambda control disconnected, fuel pump jumped. Second video is with Lambda control connected. Switched out the relay and it buzzed just as the second video.
    Attachment 632298




  16. #16
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    Quote Originally Posted by jayona View Post
    First video is with Lambda control disconnected, fuel pump jumped. Second video is with Lambda control connected. Switched out the relay and it buzzed just as the second video.
    Attachment 632298



    Hi Jayona, I can hear the injector(s) squirting fuel when you first turn on the key. This means the engine is probably getting flooded with fuel when you try to start it. Try leaning the fuel mix 1/8 turn (CCW on the 3mm allen screw). If the injector(s) still make the 'squirting/whistle' noise after the first 1/8 turn ccw adjustment, do another 1/8 turn ccw. Keep record of your adjustments!

    Hopefully it's just an adjustment issue, and not something like a stuck fuel meter piston/plunger...
    Tbd

  17. #17
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    Quote Originally Posted by epmedia View Post
    Hi Jayona, I can hear the injector(s) squirting fuel when you first turn on the key. This means the engine is probably getting flooded with fuel when you try to start it. Try leaning the fuel mix 1/8 turn (CCW on the 3mm allen screw). If the injector(s) still make the 'squirting/whistle' noise after the first 1/8 turn ccw adjustment, do another 1/8 turn ccw. Keep record of your adjustments!

    Hopefully it's just an adjustment issue, and not something like a stuck fuel meter piston/plunger...
    Thanks Epmedia for posting the videos. Is it possible for the injectors to only whistle when the Lambda Control is hooked up? They don't squeal with the LC disconnected and I had to give the adjustment screw more than a full turn for them to begin to make noise, I then backed off per instructions. With the the LC connected, the noise is immediate and much louder than the injectors. I thought it might be the Frequency Valve because its so loud but it sounds different to me without the engine running. I can get a vid of the injectors being made to squeal w/o the LC.

  18. #18
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    Quote Originally Posted by jayona View Post
    Thanks Epmedia for posting the videos. Is it possible for the injectors to only whistle when the Lambda Control is hooked up? They don't squeal with the LC disconnected and I had to give the adjustment screw more than a full turn for them to begin to make noise, I then backed off per instructions. With the the LC connected, the noise is immediate and much louder than the injectors. I thought it might be the Frequency Valve because its so loud but it sounds different to me without the engine running. I can get a vid of the injectors being made to squeal w/o the LC.
    All I know is that the injectors should not squirt fuel (whistle) by just turning the key on.

    --- just thinking out loud here...
    Maybe the Lambda was disconnected because the 'throttle switch' was/is stuck in the closed position? (simulating full throttle). Even maybe said switch and the 'speed relay' are stuck in closed position causing symptoms of over-rich fuel mix adjustment? Possible, I suppose.

    That pulse valve gets it's pulse-signals from the Lambda unit, based on sensing of O2 sensor, throttle switch, coolant switch and speed relay. The pulse valve manipulates the fuel control pressure. Fuel control pressure will affect how the 3mm fuel mix screw should be adjusted.
    Tbd

  19. #19
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    Running 1980-83 with out the frequency modulation valve hooked up and working these 1.8L will go down in power still run though and pretty well. The ECU is stopped from adjusting fuel when cold during warm up by the 17 deg Celsius Engine temperature Switch, @ 3500 rpms due to the speed relay and at full throttle due too the WOT switches.

    Randy
    Last edited by 320iAman; 06-29-2018 at 10:34 AM.

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