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90 bmw o2 sensor 525i


troysmith
08-27-2007, 06:53 PM
i have had a surging problem with this car for sometime and no good results i noticed there is no change in anything by unpluging the fuel pressure regulator so i thought maybe that could be part of the problem then just a few days ago i unplugged the o2 sensor and the car runs way better.. alot more low end torque going up hills in OD .. what exactly is this telling me? do i need a new o2 sensor or is this one telling the computer the car is rich or lean and making the fuel compensate for it .. im alittle confused but i am driving it with the o2 unpluged..

sidewinder69
09-01-2007, 09:53 PM
I have the exact same problem with my 92 535i. Mine does the surge but only when it is at operating temp (noticed that today.)

It really doesn't surge anymore? That's mint. So I guess what it's telling the engine to do is cut the fuel so that it doesn't overheat, only problem with that is then the temp drops too much and the O2 sensor tells the engine to increase fuel causing the surge.

Does it surge while driving, or just while idling? Mine only surges when at operating temp and sitting idle. BTW it calms down a bit when I shift it into neutral on automatic tranny. Or when in neutral and revving it just a bit (200 rpm over normal idle.)

Take a look at your ICV. And clean it if it's dirty. I linked the site in another post, so find it.

Also calm down, some of us have jobs/lives that we have to live and therefore can't be on here 24/7. If I can help in any way I try to post (when I can) ideas/possible solutions, that doesn't mean they will necessarily work either. If you feel you aren't getting answers to your questions by all means go to another site, hopefully someone can help you out.

troysmith
09-05-2007, 08:01 PM
thanks man i was just having a bad day but you have been a big help and you seem to know what your talking about so i trust you and you opinions... mine does it when im pushing it kinda hard but now that i have the o2 sensor unpluged it doesnt do it at all.. as a matter of fact it has alot more torque going up hills it doesnt downshift anymore.. runs lots better but i know it isnt right with that unpluged..thanks for you help you always seem to be there when i have a question so thanks and if you find out anything new let me know..good day to all

sidewinder69
09-09-2007, 01:19 AM
Honestly if I think I can lend a hand I throw the hopeful answer in there.

Although usually if someone has a problem I'll try and find an answer on another website. That's why I post links all the time.

Yeah the thing with pulling the O2 sensor is that you'll have a lot more fuel being sprayed in cause the engine is just guessing at the correct air/fuel ratio, the shitty thing about that is you could start getting backfires because you have raw fuel pissing out of your exhaust. Hence the extra torque uphills due to an increased fuel to air ratio.

From www.howstuffworks.com: "When the oxygen sensor fails, the computer can no longer sense the air/fuel ratio, so it ends up guessing. Your car performs poorly and uses more fuel than it needs to."

Also your Catalytic Converter is designed to burn off pollution causing chemicals left in your exhaust. To perform the chemical reaction it needs to be very hot so if you push your car hard uphill then turn the engine off your Cat could possibly start burning that raw fuel left in the exhaust and you could have an exhaust fire...not good.

Also try buying a $5-$10 bottle of fuel injector cleaner. It DOES work if your injectors are gummed up. See if that helps, it's a lot better than buying that expensive ass O2 sensor. Then again you might just have to bite the bullet and get a new sensor.

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