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Steve
01-06-1999, 09:21 PM
6 months ago I purchased an 89 525i. Overall it is in very good condition. When cold the idle is perfect, after a minute or two it is rough. Very smooth acceleration. I replaced one small vaccum hose which slightly improved idle. Does this sound familiar to anyone else?<p>

ron
01-06-1999, 10:36 PM
<i>: 6 months ago I purchased an 89 525i. Overall it is in very good condition. When cold the idle is perfect, after a minute or two it is rough. Very smooth acceleration. I replaced one small vaccum hose which slightly improved idle. Does this sound familiar to anyone else?<p></i>Steve, sure does! See my note from jan 5 "Idle thoughts..." and John Orlando's answer. I haven't tried the reboot idea yet, but it sure sounds like it's worth a try...just have that radio code handy after you reconnect. You didn't say what rpm you're seeing, but i was told it should be between 625-700 with all accessories off. Good luck<br>ron<br>89 525i

Michel
01-07-1999, 10:02 AM
One possibility could be your o2 sensor. I have a 1993 525 (m50)and had some idle problems like you described. I changed the 02 sensor and it runs much better. <p>When the car is started and the engine is cold, the computer sends the injectors a certain amount of fuel regardless of emissions (open loop operation). Once the engine has warmed up to 500-600 degrees it transitions to the "closed loop operation". The closed loop operation takes into account how much fuel is being wasted or needed in the fuel/air mixture. This is detected by the o2 sensor in the exhaust system (detects whether lean or rich). The sensor sends this info back to the computer in order to adjust the proper air/fuel mixture which is sent to the injectors. This is where you might be getting bad feedback and the computer is sending info that will cause your engine to idle rough. <p>This worked on my m50 engine. I don't think the logic would change among the different BMW engines produced in the late 80's/early 90's. Just look into this and good luck.<p>If you have any more questions about this subject, I will be happy to try and answer them on this subject.

ron
01-07-1999, 01:17 PM
<br></i>Michel, are there any other symptoms for a bad O2 sensor? The suckers aren't cheap. TIA<br>ron<br>89 e34

TBM
01-08-1999, 01:05 AM
I beleive there is a test procedure for the O2 sensor in the Bentley manual. As far as replacing, I have used genereic (4) wire FORD sensors. Same signal, heater, and thread. They are also about half the price of the Bosch original ($85 for the Ford, 160 for the Bosch). Check out www.mesaperformance.com. These guys know there stuff and can supply the cheaper O2 sensor. Its BMW orignal, but I bet both the bosch and Ford unit are manufactered in the sam place.. They look exactley like each other.<p>TBM<br>89 525i<br>85 325e

Michel
01-08-1999, 04:50 PM
Other symptoms I encountered were sluggishness, low gas mileage, and hesitation when I accelerated pretty hard. You might want to check and see if there are any holes in your down pipe (pipe leading from the exhaust manifold to the catalytic converter). If there is a hole it will cause the o2 sensor to send invalid air/fuel mixture to the computer.<p>If everything is clear you might want to use some chevron techron injector cleaner. Due to the fact that your car is an '89 it might be good to take your injectors out and have them "backwashed". This allows any debris which may have built up over time to be expelled from the opposite, larger end of the injector. If the injectors' spray pattern is drippy instead of a fine mist, then this will cause you to have a rough idle.<p>Good Luck!<p>By the way, IMPARTS sells your o2 sensor for $105 (Bosch) which is cheaper than the dealer.


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