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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 5 Series > E39 (1997 - 2003)

E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 01-18-2013, 03:07 PM
gomolka30 gomolka30 is offline
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Mein Auto: 2001 530i
Pleasant Surprise

On my way home from work today I noticed a slight change in how my car was driving. For the past couple of months I noticed that my car was running a little bit rough and throwing a lean code. So in the middle of driving, the steptronic changed up a gear and at this point the rough condition went away. I look down at the dash, and the SES light went off. Fairly soon after the MPG computer started to climb as well.

My question to all all out there, what do you think could have been the issue?

For a while, my car has been throwing P0171 and P0174, occasionally P0313. Fuel pressure is good. Just recently it has thrown P0430. Not sure if it is a bad cat or sensor yet.

Today's weather conditions were some of the coldest and driest yet this winter, around 32F high and low humidity.

I'll reset the codes and see if it throws anything new.
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  #2  
Old 01-18-2013, 05:01 PM
edjack edjack is offline
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Sounds like a vacuum leak in the intake tract. Carefully inspect the bellows around the entire length and circumference, which can tear. Inspect other hoses, too.

The cat efficiency code can often be fixed by replacing the post-cat O2 sensor, but I'd fix the vacuum leaks first.
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  #3  
Old 01-18-2013, 07:24 PM
gomolka30 gomolka30 is offline
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I'm guessing there is a vacuum leak somewhere too. Not sure where yet. But don't you think cold dry air would make the crack worse and let in more air? That's my confusion. What suddenly happened to cure a month long (small) problem? And it definitely was sudden. The rough running condition was actually accentuated for a brief moment just before it got better. Due to this I suspected something was either sticking or plugged, unrelated to the lean codes. Maybe a slightly sticky valve, or a progressively clogging cat that freed itself because of increased exhaust pressure. What works against this theory is that the engine seems to rev great if you get on the gas. It's the intermediate/light throttle where the rumbling occurs. When I first bought the car I suspected either engine or transmission mounts.

I'm going for a drive now. I'll reset the codes and take a spin. The engine is cold, 28F right now outside and sitting for 5hr.
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  #4  
Old 01-18-2013, 08:32 PM
gomolka30 gomolka30 is offline
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Yeah, so the SES was triggered only a couple miles into the run, 3 pending codes, the normal 0171 and 0174, and also P1093. LT fuel trim is about +4% in both banks, and ST fuel trim is about +23% in both banks. Surely a vacuum leak somewhere. I'm still stumped on why the SES light went off during my ride home and the engine seemed extra smooth.

My o2 sensors seem to be reading OK. Pre cats fluctuate but usualy read .3-.8V. The post cats are both reading right around .1V. I doubt I got the cats hot enough to do their job properly. Only a 3 mile round-trip.
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  #5  
Old 01-18-2013, 08:41 PM
pleiades pleiades is offline
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Probably a fat loogie of heavy CCV phlegm has temporarily plugged your vac leak before continuing on its merry way toward an injector.
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  #6  
Old 01-18-2013, 08:50 PM
gomolka30 gomolka30 is offline
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Haha, you could very well be correct. I have no idea how bad my CCV system is working. I'll try the classic oil filler cap test tomorrow.

My oil dipstick only once showed a tiny dot of mayo. It almost always is clean oil. Are there other easily accessible CCV tubes I can use to test for proper function?
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  #7  
Old 01-19-2013, 09:44 AM
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bluebee bluebee is offline
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Vacuum leak.

Lift the bimmer and look at it from below to trace the lower CCV hose from the dipstick to the CCV.

Betcha, if yours hasn't been replaced with the newly designed version, that it's cracked one inch below the CCV.
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  #8  
Old 01-19-2013, 10:55 AM
gomolka30 gomolka30 is offline
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I don't doubt it. It's rough on the body trying to do anything like that with limited daylight in a northeast winter (although it is quite nice outside today). Do I need to take off the plastic splash guard?

Actually, I may have found a culprit of the majority of my air leak. I temporarily swapped in a good DISA and my short term fuel trim was close to 0%. Once the car was fully warmed up, the short term moved into negative territory, about -15%, with long term still at +3-4%. The standard P017x went away, but was still throwing code P1093.

It seems like my car should be able to make it through the winter fine. Once spring time comes, I'll look to replace lots of vacuum lines, new DISA, probably new CCV system, new plugs, and check coils. I might get the injectors cleaned as well. Pretty sure there are no air leaks around the injectors from a carb cleaner spray test.
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