5-Series (E12,E28, E34, E39, E60)Chat relating to the BMW 5-Series of all generations. Specific models include: BMW 518, BMW 520, BMW 520i, BMW 530i, BMW 528i, BMW 530i, BMW 518i, BMW 524d, BMW 525i, BMW 525e, BMW 528e, BMW 540i, BMW 535i, BMW 520d, BMW 525td, BMW 525d, BMW 530d, BMW 525i/xi, BMW 530i/xi. (BMW 5-Series Forum)
My 1999 540i has lost power from 1000---3000rpms. It idles good and runs smooth until you get on it, then it bogs and has no power until about 3000rpms It is almost like a turbo kicking in. If you hold the accelerator steady... just above idle in park 1000 to 1500 rpms it drops to 500 then back to 1500 in a 1 second cycle frenzy. I pulled a code that was an off idle stumble and aging o2 sensors. The car has 80,000 miles and I do not know the service history. could o2 sensors cause this kind of problem? Any input would be greatly appreciated.
You pulled a code that was an off idle stumble and aging 02 sensors? Im not familiar with that sort of code. Do you have a # for the code? 02 sensors normally do not cause what you are describing. I would maybe check MAF and also check for vacuum leaks and check PCV plate.
I had a similar problem with my 540i, i also have hit 80k. It was fine idiling, but dead sluggish tootling about and when you wanted to jump out anywhere it didnt want to go, then all of a sudden your heads thrown back as it decides that you put your foot down 5 mins ago.
After lots of googling and not much help from BMW, i found that i had a faulty MAFS. If you look from your air filter box then run along the air intake hose there is a round cylinder with a sensor screwed into it, its easy to spot. Its a Bosch sensor and when you buy the sensor it comes with the round bit too, so dont worry about buying the funny torque screw drives with the centre hole in them.
I replaced mine and it was like someone had bolted on more engine, not only did it solve the problem it was a damn sight faster too. The MAFS isnt cheap, i was quoted about 180quid, i managed to get it cheaper, i have a friend who works at a parts counter for a dealer and he got me a good discount.
Do you have the yellow light on your dash to the bottom right, mine was on with this problem, it went off about a day after i replaced the MAFS.
ANy questions about this give me a shout.
__________________ "In a world without Fences who needs Gates"
I misstated one of the codes-- aging o2 sensors was correct, but it was an off idle mixture that was the other one (cylinder 1-4.) I replaced the o2 sensors.... with 80,000 miles they were due. It then set a code for a bad o2 sensor on the same bank (1-4) and started idling rough which made me think vacumn leak. I did track it down to the f air system(?) and found a bad hose. Right now it is running good. Thanks for all the help. My Chevrolet has 105,000 miles on it parts are half the price and I never have any trouble with it. Sometimes I wonder if BMW'S are worth it!.....BUT THEN YOU OPEN IT UP AND THE HANDLING IS SO AWESOME!!!! On another note to my British friend My maf sensor went bad on my 1984 Volvo and the car would barely run yet it would test good with a voltmeter (No self diagnostics on these). Replaced it and now the car will hit 60 in less than a minute! WOW
Im really glad you sorted it, i Just got mine back, had to get some wheels direct from BMW, expensive, but I have my baby back, will do some more pics of it later. Only thing is the accident i had had shocked my air condenser, so need a new one of those, more money down the pan, but shes worth it!!!
__________________ "In a world without Fences who needs Gates"
Well the goofy thing is back to running like crap again. Now it idles rough and is a little slow on pick up till about 2,000rpms. Here are the codes it set with a peake tool table OF ...1A Mixture control off idle cyl 1-4 ... 0A Pre cat o2 sensor (new) and 1C mixture control idle cyl 1-4 I wish I had a spare MAF, I would plug that in and see. I will check the pvc tommorrow and go from there. At least the codes are consistent.
Well i swapped the o2 sensor to cyl 5-8 and it set a code on that bank. Called the parts company and they are sending me a new o2 sensor. It seems I am getting a lot of name brand parts lately that turn out to be crap! I am not sure that will totally fix it, but it is running way rich.
not sure it this will help but, my 535 had a problem with stumbling and power loss, pretty harsh at times. It drove me nuts as it would disappear and then come back for no apparent reason. Anyway checked the codes that came up and none of them seemed to fix the problem. of course the codes wouldnt clear, so to see if the same codes would come up again. I did a hard clear by disconnecting the ECU. poof codes gone engine running great. I got a can of contact cleaner and cleaned the crap out of the ECU edge connectors and the plug and havent had it since. (knocking on wood right now). Just a shot in the dark
if not...it could be the oil separator, which is a vaccum leak.
Symptoms of a bad oil separator would include:
white/blue smoke out of your exhaust on acceleration
"sputtering" on acceleration and a "whistling" noise
Car moves normal at higher speeds (early stage...later stage, it gets worse)
Well I am finally back on the road again. Replaced the new failed o2 sensor and it ran much better, esp at idle and set no codes. Still did not feel right so I broke down and replaced the maf sensor. This fixed all the problems .........until it quit running and on restart would not idle. Finally limped it home and pulled a bad maf code. I just replaced the new bad maf and everything is perfect. Wow, what an ordeal...What is up with bosch parts? I have never seen so many bad parts coming from reputable sources. All the problems i have had are with parts made in Germany. Are they drinking too much beer over there, or did i just get a bad run of 3 parts? (see my brake thread) Thanks to all who helped with this cluster ----.
I have a hard time believing you had 3 bad parts, unless you were using cheap aftermarket parts. Maybe you had more than 1 problem going on or maybe the o2 sensor faults were related to the Maf failing. Either way time will tell to see if it is really fixed this time... I hope it is.
Also there is a reprogram that will get rid of the "aging" 02 sensor faults if your car falls in the production range. It is not a recall however so you would have to pay a dealer to perform the programming. The bulletin applies to E38, E39, E53 with M62TU produced from 09/98 up to 09/02 and you can have your dealer refer to SI B12 09 02
Thanks for the response....My guess is the aging o2 sensor was not the main problem, but when I replaced them it definitely created a problem. These were bosch oem parts in bosch boxes. Could be they were returns or something; anyway the car is still doing fine.
I worked as a professional auto mechanic and machinist for 10 years and was trained at Mid Florida Tech for 2 years. I never ran in to parts issues like these, but then they were not computer run when I was born either.
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