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Registered User
Join Date: May 2012
Posts: 13
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1992 325i erradic idle
My BMW idles goes up and down from 800rpms to 16-1800 over and over , but when I pull off the mass air flow sensor plug in the idle goes down to 600 and I have a feeling that it might also be the idle air control valve, any help is appreciated!!
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05-29-2012, 10:09 PM
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Registered
Join Date: Sep 2005
Location: Sacramento CA
Posts: 1,147
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More likely an air leak in the intake tubing, a dirty throttle body, or a vacuum leak.
Dismantle everything from the air filter to the intake manifold. Clean the MAF, throttle body, and idle air control valve with MAF cleaner. Check all tubing for cracks. If you still have a problem, get some starter fluid (ether) and start looking for vacuum leaks. |
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05-30-2012, 05:36 AM
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Ben. T
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I had the exact same issue, and the thing we've found out is two key things about our cars
1: BMW has a system in the car that reads what the temperature of the car is, so when the car starts up, the idling should be much higher. Mine sometimes revs all the way to 2000 rpm 2: I replaced mine with idle control sensors that I knew had worked from a previous car and it has helped immensely. Because of the programming, you have to unplug, then replug your ECU after you do the swap, but after that you should be able to start right up. the only other point is this: don't press the pedal at all during start up. It confuses the programming and increases the revving issues. Hope that this helps! |
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06-06-2012, 03:56 PM
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bostongrun
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The idle control valve only provides air when the throttle body is closed. If your idle control was bad you would find your car killing when you take your foot off the accelerator. I would venture that you have a rip in the air intake bellows elbow, a very common problem. It causes a big air leak.
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06-24-2012, 01:45 PM
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Registered
Join Date: Oct 2005
Location: Florida
Posts: 668
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Sorry, I didn't notice the origenal date of this post, it is one of those ones that seem to come back from the dead. The guy may have sold the car by now. I won't erase my comment incase someone else finds it useful.
Reply three weeks late was.... All true, and it could sound confusing to someone who has this problem, but never had to diagnose it. Do first, exactly what Manilito said. A BMW with an intake air leak will not idle correctly. The engine control module cannot get control of the idle if it cannot control the inlet air. If that does not correct it, then it gets a little complicated. First, there is no such thing as "idle sensors". The engine control module uses information from several sensors to maintain idle. MAF sensor. Mass air flow. (volume) intake air temperature sensor Crank shaft position sensor. Cam shaft position sensor Throttle position sensor O2 sensors The engine control module then uses this information to send the signals to; The idle control valve, (which is better discribed as an idle AIR control valve), The ignition coils, to control the ignition timing and the fuel injectors, to control fuel delivery. If there are no leaks, and the idle conrol valve is clean. look for fault codes. if you get a lamda code it is a o2 sensor, very common cause of poor idle.
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74 911 targa blk on blk, Carrera fend., tires & whls. gone, missed 85 325e bought new, totaled after 20 years & 465K miles, trouble free service. 01 Ford Ranger 4dr stpsd 4wd. I drive,here 88 325i convert. only 98k miles,gone, sold 93 325i.here, 98 Z-3 roadster. gone, 08 128 cabro gone Last edited by coolbear1; 06-30-2012 at 10:21 PM.. |
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06-30-2012, 09:29 PM
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