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Thread: It Was The Darn Donuts That Ate My Lunch!

  1. #1
    Join Date
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    It Was The Darn Donuts That Ate My Lunch!

    I changed out the other new CIS with the old oem wire/sensor and car ran beautifully. I changed one of the new sensors a week ago and finally got around to replacing the other wire this afternoon. Then I went on a 2 1/2 test drive this evening and I did not have any intermittent problems, trans fail-safe mode, or LHM issues. I could not detect any hesitation when slowing a bit while cruising along on the interstate. Engine responded perfectly, dropping down a gear if I got in to the throttle hard enough, or just applying power and slowly accelerating up to 80 or 90 mph.

    Now I would like to notify the manufacturer and relay my experience. I did test the resistance of all the sensors I have including two NIB sensors I bought to test, the old bmw sensors, and those on new sparkplug wire set I bought from Turner. All of the sensors tested around .3 ohm except for one on the new wire set. I changed that a week or so ago with the old bmw wire and that did not correct the problem until I replaced the second one. I am wondering if the silicone insulation on new wire sets is too thick and possibly disrupting the signal? Sure would be nice to figure out why the aftermarket sensors are faulty because the wire sets appear to be of good quality using German-made Beru and Bremi connectors. The donut sensor has no brand or identifying marks on it though.

    I also changed the MAF sensors last weekend since the car had the original sensors. I bought two new Walker Products sensors and they seem to work just fine. I called Walker and spoke to a tech and he said their sensors with dual thermistors should work much better than the old wire filament design used on the cars when new. He said the thermistors are much more precise and durable than the wire filaments. He also said that K&N types of oiled filters will not harm the MAF sensors as long as the filters are not dripping wet with oil. He said the K&N filters work fine right out of the box, just dont over soak them with oil when cleaned.
    Last edited by JDP530; 04-04-2018 at 11:17 PM.

  2. #2
    Join Date
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    Quote Originally Posted by JDP530 View Post
    I also changed the MAF sensors last weekend since the car had the original sensors. I bought two new Walker Products sensors and they seem to work just fine. I called Walker and spoke to a tech and he said their sensors with dual thermistors should work much better than the old wire filament design used on the cars when new. He said the thermistors are much more precise and durable than the wire filaments. He also said that K&N types of oiled filters will not harm the MAF sensors as long as the filters are not dripping wet with oil. He said the K&N filters work fine right out of the box, just dont over soak them with oil when cleaned.
    This is interesting, my experience so far with single wire mafs from ebay was quite the opposite. There is still a box full of them at late Jon's ranch, all useless.
    Keep us posted on how the car runs with these, maybe Walker worked some magic on these or just used much higher quality components.

  3. #3
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    Quote Originally Posted by dragon850 View Post
    This is interesting, my experience so far with single wire mafs from ebay was quite the opposite. There is still a box full of them at late Jon's ranch, all useless.
    Keep us posted on how the car runs with these, maybe Walker worked some magic on these or just used much higher quality components.
    There are actually two standoffs in the inner velocity tube each with a thermistor mounted on it. If I am not mistaken, one of the thermistors has a constant voltage going to it and the other varies depending on the flow of air across it. I guess the DME determines what the airflow or mass of air is based on the differences in voltage between the two thermistors? Maybe Scott can explain the thermistor theory so we can better understand how the sensor operates.

  4. #4
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    Quote Originally Posted by JDP530 View Post
    ... K&N types of oiled filters will not harm the MAF sensors as long as the filters are not dripping wet with oil. He said the K&N filters work fine right out of the box, just dont over soak them with oil when cleaned.
    The problem is that the K&N filters by design have to rely on a fairly good oil coating to trap the smaller particles of dirt from being ingested into the engine. Personally, running a quality paper filter seems much safer (and also less expensive than the K&N's).
    '93 850Ci - Mineralweiß Metallic

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  5. #5
    Join Date
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    Glad to hear you got it sorted out, JD.

    - - - Updated - - -

    +1 with TxGR8. So which brand is considered to be offering quality air filters? I typically use Mann or Mahle. What does everyone else use?

  6. #6
    Join Date
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    Quote Originally Posted by TxGR8White View Post
    The problem is that the K&N filters by design have to rely on a fairly good oil coating to trap the smaller particles of dirt from being ingested into the engine. Personally, running a quality paper filter seems much safer (and also less expensive than the K&N's).
    I am using the Wix right now. Would be interesting to know which filters provide the best filtering and with the least resistance.

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