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Thread: HVAC related EML issue???

  1. #1

    HVAC related EML issue???

    Hello Mafia,

    I am a long time member who NEVER posts, but I do lurk and read a ton of info on this forum. I hope to contribute more in the future....

    I am a pretty experienced hack mechanic and have been trying to trouble shoot an issue on my 03 Mystic ZHP sedan. I recently changed out the DISA, Cleaned the ICV and MAF and replaced the CCV with the foam coated cold weather pieces. I was having much complained about cold weather rough idle start conditions... After much internet research and tearing the whole thing apart I found that the lower CCV drain hose to the oil pan was not fully seated and creating a vacuum leak. I replaced it and have had a perfect idle at start up ever since no matter how cold or long the car has sat. (I also cleaned out the dipstick tube where yellow sludge can accumulate at the bottom of the CCV drain hose)

    The issue I am now facing may be related. Twice since I performed all the work my car has gone in to limp mode while driving. Both times I was able to pull over and restart the car by turning off the HVAC system and then cycling power with the key to position 2 and off. It is mind boggling to me how the HVAC system could be causing my car to go in to EML mode. A little history.... I have replaced the battery several times in my car since purchasing it in 2006. I did some research years ago and found internet info about a parasitic draw from HVAC (FSR), but my car did not exhibit any of the fluctuating fan speed or post shutdown continuous fan symptoms so I never replaced the FSR. I did however start using a tip that I found which was to simply "reset" the car by turning the key to position 2 without starting every time I shut the car down. This has magically helped me to keep my battery charged for several years without replacement. But now I am experiencing the EML issue which is very sporadic. As I mentioned earlier I believe the HVAC is part of my problem as both times I have gone in to EML mode I have had to shutdown the HVAC system in order to cycle power and get the car running normally again. Is this just a coincidence? Has anyone ever experienced this before? Note that the first time this happened I cranked the heat after a cold day on the golf course and the car went in to EML mode at about 35MPH after 10-15 minutes of driving. The second time the car went in to EML mode I had the AC on fairly cold and was stopped at a traffic light with the car idling in 80 degree heat outside.

    I pulled codes after the first heat on/ cold day EML issue but have not had a chance to pull codes again after the more recent warm day A/C issue. All I got was some mis-fire codes.

    I have read that there is a known issue with HVAC programming that can be re-flashed by the dealer. If anyone knows anything about this, please arm me with info before I walk in to the dealer with a Mystery problem that they will surely take advantage of...

    Thanks much!

    On a side note I am more than happy to help ZHP owners in the DC area (Northern VA specifically) with garage work space, tools, lift and an extra set of hands for less than 1 day projects at my home if needed.

  2. #2
    Join Date
    Jan 1970
    Location
    Lebanon, OH
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    37,868
    OK. Go ahead and pull codes again, then report back.

    FSR parasitic drain shows all of the same characteristics as one that's failing?

    This is not a "normal" issue.

    Have you consulted with dealer regarding the re-flash comment?
    "Flame suit NOT REQUIRED!!!"
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  3. #3
    Join Date
    Jun 2011
    Location
    Redondo Beach, CA
    Posts
    1,943
    I've heard of the EML light going off due to a vacuum leak. Check out this thread:

    http://www.bmw-driver.net/forum/showthread.php?t=15140

    I believe the culprit is #3 in this diagram:

    http://www.realoem.com/bmw/showparts...03&hg=11&fg=45

    Might be worth inspecting.
    2006 CiC 6MT
    ZHP, Cold Weather, Xenon
    Sapphire Black / Black Leather / Black Cube

  4. #4
    Join Date
    Jun 2011
    Location
    Indiana
    Posts
    24
    HVAC and EML may be related to the engine speed increase when the A/C compressor is turned on?
    The ECU increases the engine speed when the compressor is engaged.

    Have you checked for any codes in the HVAC and possibly the DSC/ABS systems in addition to the OBDII emission codes?

    Switching conditions for the magnetic clutch:
    ON:A/C button ON and evaporator temperature > 4C (depending on the outside temperature) and coolant temperature < 117C and terminal 30 at control unit > 9.7 Volt.
    OFF: A/C button OFF or evaporator temperature < 3C (depending on outside temperature) or blower stage 0 or coolant temperature > 120C or terminal 15 OFF or terminal 30 < 9 Volt.
    Switching conditions for DME AC idle boost:
    When the A/C button is pressed, the heating/air conditioning system requests an idle speed boost via the K-bus in order to provide adequate cooling capacity at idle speed.
    ON: A/C button ON and outside temperature > -10C.
    OFF: A/C button and DME_KO OFF or blower 0 and DME_KO OFF or outside temperature < -10C and DME_KO OFF
    DME_KO compressor activation:
    The DME/DDE receives the instruction to switch on the compressor via the K-bus. Provided full load cutout is not active, the DME switches on the compressor via a relay. The load moment of the A/C compressor is derived from the pressure sensor signal and passed on to the DME/DDE via the K-bus.

  5. #5
    Sorry for the delay in getting more info back to you helpful folks..... I hate it when people start threads and never resolve them. So I followed Dane's advice and went to pull the codes again, only problem was that for some reason my Peake/Bavauto code reader kept getting error messages and would not read codes. This set me back about a week until I decided to go to Autozone and buy a new actron code reader. In the meantime the car went in to EML limp mode again while returning from a dentist appointment, same conditions as previously stated only this time it was a mild morning and the HVAC system was completely off which blows my theory of HVAC having anything to do with my problem......

    I have been scouring the web for more info and here is where I am at:

    The car gave me code P1632 Throttle Actuation.

    I have found reference all over the net to a common wiring issue in the E46 engine harness, which makes sense because my problem is intermittent. It must be electrical because it only goes in to EML mode randomly and can easily be reset to normal operating conditions.

    I am going to try to carefully examine the engine wiring harness today and pay close attention to the connections at the throttle body. I can replace the entire wiring harness for less than $400, but hate to take on that much work and expense if there is one or two bad wires that can easily be fixed. The problem is that I am not very good with electrical system diagnosis and feel like I am searching for a needle in a haystack.... Can anyone chime in that may have had a similar "common issue" with their ZHP? It would be very much appreciated if someone could point me to the specific area of the engine wiring harness to look...

    THANKS!! (I will report back all findings and hopefully a solution in the end!)

  6. #6
    Information that I forgot to include: I actually replaced the FSR thinking that it was part of the problem. Good news is I had the old style and now have the new style with more pins. Fan speed seems much better and does not hunt anymore. Bad news is that I still have my EML issue which seems to be completely unrelated...

    Thanks again for any and all help. Cold beer on this fine Memorial weekend in NoVa for anyone that can help me diagnose and solve this nagging problem...

  7. #7
    Update: Upon inspection, I found that the plastic electrical connector on the throttle body has a crack in the plastic connection housing. There is a half moon piece broken of which is leaving the internal electrical connection somewhat exposed to the elements. The connecter still works, but there is definitely a piece missing from the connector that unfortunately is on the TB side of the connection. Could this exposed connection be causing my throttle response adaptation issue?.....

    I have cleaned the connection and applied some dielectric grease. I am also going to try to cover the connection a bit with some electrical tape..... We'll see if this fixes it....

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