so, my idle is really low, about 600. it's always been this low. when it was bone stock, and now with 19lb injectors and an m30 afm. i have adjusted the gear in the afm so i believe it's at the best setting now, but it still runs rich at idle and it's really low. sometimes when i first start the car, it will run really roughly (400-900 rpm jump), and sometimes when it finally idles, it will smell like fuel and the check engine light will turn on until i r3v my engine. so, how can i lean out my idle and hopefully raise it a few rpms?
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That really sounds more like a leaking vacuum line. There are a multitude of little hoses connected to the throttle body and intake mani. any air leak after the AFM will make wierd things happen.
Adjusting the AFM isnt a good idea without a means of precisely seeing what it does to the air/fuel ratio.
Also check and clean the idle air control valve.--Will -
The AFM is non-adjustable. Don't fuck around with it. Something else is wrong with your car.Comment
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ok, well i'll check for vacuum leaks. all the metal connectors to the throttle body are pretty much loose and stripped... air could be getting in through that. i know where the stock afm gear position gear was, so i could always put it back, i've just heard that a lot of people said it ran best when the spring was loosened two click of the gear. any other advice? i didnt think it'd be a vacuum leak because it's so rich, and i figured extra air would mean lean, not richComment
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Well, more fuel and more air. Got the programming to boot?
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no, im running stock chip. i figured, it was built to adjust the air and fuel mixture, why can't it do the same with my setup? it does run very well, throughout the range. i did find one leak, so the idle isnt rough anymore, but its still on the low side and if i rev the engine, it will drop to about 400 rpms, almost stall (lights dim), but then it'll recover. do i really need a chip, or is there something that controls the idle that i can adjust?Comment
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there is nothing you can do to adjust the idle - all you can really do is make sure there are no leaks and everything is working (clean/working ICV, properly adjusted TPS, etc).
aftermarket chips tend to leave the idle stock anywayComment
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there is a way to adjust AFR on m20s, it's an allen bolt on your AFM, usually covered by a little blue cap so no one would ever mess with it. You do need proper equipment and knowledge.Comment
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You have something else wrong, however if you want to raise the idle a little you can jump the ECU to make it think the A/C compressor is on. That raises it a little bit.
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lol thanks guys. problem was fixed over a year agoComment
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i got an 87 325 with this same problem. but i have no vac leaks. how did you fix yours? if i go the jumper route what pins should i jump? would they be the ones in the ECU or the ICM?Comment
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The most common causes of this are intake leaks, a sticky or bad ICV, a bad or misadjusted TPS, or an aged O2 sensor. The only sure way of tell if there are intake leaks is to have a smoke test run. The O2 sensor has a useful life of 100k and is a scheduled maintenance item. There are other possibilities, but work through those possibilities first.The car makes it possible, but the driver makes it happen.
Jim Levie, Huntsville, ALComment
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jim, ive been chasing this idle problem for 3 months. i tallied up today how much ive spent on parts and diagnostics and smoke tests to be told by several shops that they cant find out why my car wont idle right. ive spent $2176.71 i could have bought a good working truck for that. i love this car. its uber fun to drive but i cant keep tossing money at a problem that evidently no one can find to actually fix. if soldering a jumper in the ECM or the ICM so my car thinks the a/c is on and keeps the idle where its supposed to be, then thats what i want to do. im at a lose of other options.Comment
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I'm just reading this posts,
here is my experience with idle on my 91 325i.
new FPR, New plugs , new AFM, working ICV, New ECU temp sensor, and still rough idle.
my mistake awas I was following the Bently's recomended gap for valeve adjustment,( not to mention terrible 10, 11 MPG) I readjusted the valve clearance to about 10% bigger than what Bently was suggesting and everything fell in it's place , immediate smoother idle and immediate increase in MPG it went from 10 - 11 to 17-118 MPG
try the valve clearance adjustment and also regap the spark plugs to about 10% bigger than recommended in Bentley manual, you will have a better idle if there is no leak .
hope this was helpful
HenryComment
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