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Thread: HERE'S A FIX if your E46 won't idle and you have a K&N filter upgrade 2000 323i

  1. #1
    Join Date
    Dec 2018
    Location
    Knoxville,TN
    Posts
    19
    My Cars
    2000 323i

    HERE'S A FIX if your E46 won't idle and you have a K&N filter upgrade 2000 323i

    So, out of nowhere I go to start my ultra reliable 2000 323i and I have no instrument cluster, nor dash lights. I've gotta go, so I drive it anyway. A couple of hours later I take off again, get about a half mile from home and it dies. Can't get it to idle. So, I limp it back home and start a diagnosis. My Actron ODB-II is showing P1421 and P0101 which is the mass airflow sensor. I get some good advice from this forum and decide my four year old battery might be dying, although it's showing no symptoms. So, I swap it out and sure enough I get the instrument cluster back, but it still won't idle. So, next I get the special sensor cleaner and use the whole can, following the directions exactly. Still won't idle, so I order a new one making sure the numbers match. Install it and it still won't idle. I can keep it running if I goose the throttle though. Some more advice recommends checking the idle control valve, so I hit Youtube and see the procedure. However, my 323i had been modified before I bought it to include a K&N filter upgrade, which made getting to the ICV really tough, plus now my car doesn't look like the tutorials. At this point I can't figure out for the life of me why I lost the cluster and idle within hours of each other, so I figure it's gotta be electronic, which is why my first move was to replace the MAF. So, what I learned was I could take the small inlet hose loose (the end of the ICV with the actual valve, opposite the wiring harness), which I now think may be a part of the K&N upgrade kit. Since I couldn't see inside the ICV, I shot it with the other can of intake cleaner that came with the MAF cleaner pack. Again, I can't see inside, nor can I shake it to see if the valve is moving freely, so I take a small 3" flat head and gently move it around once I felt it bottom out, and sure enough I feel it move. I then shoot it again with the cleaner (it wasn't filthy, but there was some buildup) and wipe it out. I put it back together and whatta you know, no "service engine soon" light and it idles like a champ. The moral is apparently even a slightly weak battery can cause two seemingly fairly unrelated issues, so if this happens to you, here's my advice: 1) Check the battery. I was getting 12.35V and I'm told I should have between 14-14.2V. 2) clean the MAF and if that doesn't solve it, a new one is 20.00 on Amazon. 3) if that still doesn't solve it just get to the valve end of the ICV (after checking the harness) and shoot it a couple of times with intake cleaner. I'm told not to use too much, as it can seep into the bearings and dissolve the grease. I think the key was to clean it, gently move it around, and clean it again. Hope this helps.

    **UPDATE**

    Ok, so how does a weak battery affect the instrument cluster and the Idle Control Valve? Seems completely (almost) unrelated, right? Here's the hypothosis: When I drove the car the first time that day, it was the first very cold day we'd had so far. As such, it put extra demand on my weak battery, but hadn't yet affected my ICV. A few hours later, after the car had cooled back off, it started fine, but I warmed it up a little, and after a half mile or so of driving the ICV started moving (probably closing) and it was at that point the weak battery apparently affected the ECB, which controls the ICV. When that happened, the ICV became immobile and was essentially stuck at wherever it was at the time, which caused the no start/no idle problem. When I changed the battery, it solved the power problem, but since the car couldn't start the ECB couldn't send the ICV new instructions. That's why when I jostled the valve it allowed the engine to start, which allowed the ECB to send new instructions to the IDV, effectively "resetting" it.
    Last edited by bpmgmt; 01-16-2019 at 02:20 PM.

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