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Thread: sources of vacuum leaks 535i

  1. #1
    Join Date
    Jun 2007
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    colorado
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    Default sources of vacuum leaks 535i

    I have been chasing a 1222 code and have searched and read most of what's on this site for causes of a 1222 code.
    I have replaced O2,plugs,wires,cap,rotor various vacuum hoses. I most likely have a vacuum leak. If I was reading right, a bad oil dipstick O-ring can cause a vacuum leak.

    To take that source of vacuum leak furthur, I know I have a bad pan gasket. It leaks and I found a hunk of it hanging out of the side of the pan when I looked at it on the ramps.

    My question - Can a bad pan gasket cause a 1222 code?

  2. #2
    Join Date
    Dec 2003
    Posts
    1,639

    Default Try starting here

    Does your car idle smooth? If you have a large vac leak, it will idle like crap. A small vac leak will cause a slightly rough idle. Small vac leak should not be enough to trip a 1222 code.

    Assuming it idles fine, check the fuse to the O2 sensor power circuit to make sure the fuse is not blown. Do a code clear and see if you still get the same error.

    Jeff
    Bellevue WA
    90 535iM - not much stock remains. 3.7 liters, ported head, cammed, 3.73 diffy, M5 brakes, MAFed, yadda yadda yadda
    86 Porsche 951 - Track Toy

  3. #3
    Join Date
    Sep 2006
    Location
    Coarsegold CA
    Posts
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    Default

    Quote Originally Posted by skidmark
    I have been chasing a 1222 code and have searched and read most of what's on this site for causes of a 1222 code.
    I have replaced O2,plugs,wires,cap,rotor various vacuum hoses. I most likely have a vacuum leak. If I was reading right, a bad oil dipstick O-ring can cause a vacuum leak.

    To take that source of vacuum leak furthur, I know I have a bad pan gasket. It leaks and I found a hunk of it hanging out of the side of the pan when I looked at it on the ramps.

    My question - Can a bad pan gasket cause a 1222 code?
    A 1221 or 1222 code can represent a symptom rather than a problem.

    In my case I had both those codes and the problem was fuel related which caused the mixture to go off and trigger the codes.

    Other than the code, how does it start, run etc.

    Good Luck
    Don
    1994 530it 147,000
    1983 300SD 278,000 (running soybean oil)
    1980 300TD 135,000 (running soybean oil)

  4. #4
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    Oldham, England
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    3,078

    Default 1222 code

    From what I remember this code can be generated by anything that causes the mixture to be too rich or too lean. A quick look at a plug will tell you which. I read somewhere a quick way to test if your inlet vacuum is OK is to place a plastic bag over the oil filler cap hole and see if it gets sucked inwards.
    Oct '00 E46 330i. Feb '92 525i (departed)

  5. #5
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    colorado
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    Default

    Thank you for the replys. The car does idle like crap. It does not die but sounds like it wants to. It sounds/feels like it's missing. It takes about 15 seconds after starting the car until the check engine light comes on. If I blip the throttle the light goes out(again taking about 15 seconds to come back on) If I slowly increase revs the light will stay lit (tried it to about 3k rpm and it stayed lit) when I let off the throttle the light goes out. Once under way the light stays out until I settle at a certain rev (say on the highway) then comes back on.

    I tried re-setting codes by reseating both ecu harness. The code comes back. The code did change from a 1221 to 1222 after replacing many things plugs, wires, o2, fuel filter, any vacuum hose brittle or cracked, valve cover gasket.

    I cleaned the ICV and camshaft sensor (oil leak had it a mess).

    The old plugs that came out where sorty white colored. (lean I think)

    Car seems to run OK when I get on it, and gets decent MPG 16 in town 22 on highway.
    Last edited by skidmark; 07-12-2007 at 04:56 PM. Reason: updates

  6. #6
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    Default

    Plugs should be a sort of yellow colour. White sounds like its running too lean. If your vacuum hoses are sound I'd be thinking fuel pressure - maybe the regulator? A pressure check would soon tell
    Oct '00 E46 330i. Feb '92 525i (departed)

  7. #7
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    Default

    Quote Originally Posted by skidmark
    Thank you for the replys. The car does idle like crap. It does not die but sounds like it wants to. It sounds/feels like it's missing. It takes about 15 seconds after starting the car until the check engine light comes on. If I blip the throttle the light goes out(again taking about 15 seconds to come back on) If I slowly increase revs the light will stay lit (tried it to about 3k rpm and it stayed lit) when I let off the throttle the light goes out. Once under way the light stays out until I settle at a certain rev (say on the highway) then comes back on.

    I tried re-setting codes by reseating both ecu harness. The code comes back. The code did change from a 1221 to 1222 after replacing many things plugs, wires, o2, fuel filter, any vacuum hose brittle or cracked, valve cover gasket.

    I cleaned the ICV and camshaft sensor (oil leak had it a mess).

    The old plugs that came out where sorty white colored. (lean I think)

    Car seems to run OK when I get on it, and gets decent MPG 16 in town 22 on highway.
    Did you replace those items by diagnosing each and found them to be out of spec or did you replace them in an attempt to cover all the bases? I ask because...

    If you have a manual, you can follow the various procedures to determine what the condition is of parts, rather than replace them....going forward.
    There are a lot of possibilities.

    Bentley's says your symptoms can be caused by...

    Idle stabilizer valve
    Throttle position switch
    Large intake system leak
    Fuel pressure being too low or too high
    Faulty coolant temp sensor
    Faulty oxygen sensor
    Leaking fuel injectors
    Broken or corroded electrical connections
    Broken or corroded ground connections
    CO content too low or too high
    Input signals to DME Motronic ECM missing, ECM in limp mode
    Faulty DME Motronic ECM

    If you have a fuel pressure gauge, run those tests first. If you don't have one, you can get one good enough to diagnose the fuel system at Harbor Freight for about $15.00


    Don
    1994 530it 147,000
    1983 300SD 278,000 (running soybean oil)
    1980 300TD 135,000 (running soybean oil)

  8. #8
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    Jun 2007
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    colorado
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    Default

    Yes I do have the bentleys. The items I replaced were all original equipment. (car has 60k) I do have a pressure gauge. Where is the best place to tap into the fuel line?

  9. #9
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    Coarsegold CA
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    Default

    I would follow Bentley's... that way you have a source to walk you through each diagnostic test having said that..... I did not follow Bentley's (lol) on the fuel pressure test.

    First find your fuse for the fuel pump, pull it and start the engine to bring the pressure down....

    I disconnected the fuel line (supply side) at the rail (I have a 3.0 V8) and connected the gauge there.

    Your going to need several readings...

    Running (put the fuse back)
    After shut down... check it in 30 mins or longer and note FP drop (should hold close to original psi (listed in Bentley's).
    With the FPR vacuum line disconnected (it should rise)
    Slight crimping of the rubber fuel return (off the rail) should increase.
    Finally you probably should do a fuel output test. XX amount in 30 seconds (I think) In Bentley's.

    With that info, you will know what the condition of the fuel system is....if it isn't right, another level of diagnostics will be necessary to narrow down the problem.

    Don
    1994 530it 147,000
    1983 300SD 278,000 (running soybean oil)
    1980 300TD 135,000 (running soybean oil)

  10. #10
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    Jun 2007
    Location
    colorado
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    Default

    Don, I notice you have a wagon. I've got an 03 325xiT. I will do the fuel pressure test this weekend. Thanks for all of your advice. I need to follow thru on the various things Bentleys suggest for this 1222 code. I was hoping some of the things I already did was going to fix it, but at least this is a good way to go thru and get familar with the operating system on this car.

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