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Idle Wild Problem - 92 3181

Discussion in 'E36 (1992-1999)' started by suva76, Sep 2, 2008.

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    suva76

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    Idle Wild

    Mahalo (thanks), JustOne!

    Very interesting about the alternator!

    I did not buy a specific AFM cleaner, but did use electronic-parts cleaner (on both the mechanism and the electronics); tried lubricant (spray, even light grease - numerous times - on the mechanism), but all to pretty-much no avail. The mechanism just would not close all the way after opening, so I presume that opening around its edges is what "confused" the sensor and got the idle zooming up and down. Last week, the thing was as bad as ever, stalling on me at stops.

    I had just about "thrown in the towel" when I decided to take it to a fine independent BMW mechanic, who focused on the spring mechanism in the electronics "compartment" atop the meter. He explained that the spring can be tightened (or loosened) - tightening of which should bring the "door" of the mechanism back to closed. However, for now, he tried spraying some lubricant around the spring mechanism (go for the "low-hanging fruit" first) and so far, it appears to be working OK. He showed me how to "do" the spring, so, if I have to, I can try that. I think that I would first go a step back and do what he did and spray lubricant again. I shoulda thought that it might not be a "door sticking" thing and could have been a spring malfunction, but it looked pretty obvious that the door was warped, so I figured THAT was the problem.

    Of course, it ain't over til it's over!
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    • Technical Service Advisor

    mooseheadm5

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    Do be careful messing with the spring. The screws that hold the clip that keeps the position of the spring sometimes will break off, or will strip the hole out when you go to retighten them. NEVER take your hand off the toothed wheel when messing with it and ALWAYS mark the original position of the wheel. If you let go and the spring uncoils, you will hate yourself because unless you know how many revolutions it went, you will not know how to get it back to normal. Tightening the spring will dampen throttle response and will make the car run slightly leaner for a given air flow. Loosening it will increase throttle response and will make it run slightly richer for a given air flow. Don't go more than 2 clicks in either direction if you can help it. You can move the wiper arm to compensate for the rich or lean running, but unless you have a good way to monitor the exhaust gases or are a good seat of the pants tuner, I don't recommend it. Look for burrs around the edge of the door, or for a lightly warped door. Good luck.
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    suva76

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    Idle Wild

    Excellent tips, Moose! And I did get similar cautions from the guy who helped me with it last weekend, including the one about only going two "clicks" at a time. Yeah, he also mentioned that tightening the spring would likely dampen the throttle response - I presume resulting in even less grunt when starting-off - just what this little 4-banger DOESN'T need! Anyway, yes, caution IS the word here! Thanks, again!

    just1318is guest

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    Yeah, i know that one! i am currently having a problem finding a new gauge cluster for my e34. apparently it can be a difficult dealing with this issue on these cars. anyway mooseheadm5 has great advice, i would definately use extreme caution when opening and adjusting your afm spring, the one on my 318is is sealed! i would go with his approach though, thats also the way i learned to do it in my auto tech classes. i have also been told how to test the voltage to the afm and i'm sure the bmw tech you went to knows how to test it or maybe he already did. i had also looked into changing my "door type" afm for one of the round plastic ones like on the later 318's but never followed through due to price... and the time to do all the searching and part # matching. but if you need to buy a new or rebuilt one you may be interested in this idea. happy wrenchin'!
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    suva76

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    Idle Wild

    Mahalo, "Just"!

    So far, the little spray of "Bitron" lubricant seems to be holding up. BTW, whilst the MAFM "control center" might APEAR to be "sealed", mine opens - you have to dig out the silicon (or whatever they used a the factory) sealant around the edge - a bit of a gooey job, and it actually goes down almost 1/4-inch, so you have to keep at it. Then you have to carefully pry the top off and voila! The sealant around the edges is apparently to keep dirt/moisture out.

    Dang, now ANOTHER problem - this time back to the '92 325is we have! The plastic neck for the upper radiator hose "gave up the ghost" yesterday. The GOOD part was that I was at my tech's house to work on other probs this bugger has! We were just about to remove a door panel when there was this "pop", then steam comin' from under the hood! I said, "This can't be a good sign!" in a classic understatement! Fortunately, there was enough of the lip left on the radiator side to get the hose back on. Seems to have held well on way home. Bought a cheap, Thailand-made radiator later (yeah, I know, you get what you pay for, etc., but we are not intending to keep the car a whole lot longer).

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