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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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Old 01-03-2018, 11:14 AM
aktansrt aktansrt is offline
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Both Camshaft Sensors and Burn Failure in all six cylinders

I wanted to report my experience, and the final solution in hopes that it might help someone diagnose and quickly fix a similar issue like mine.

It started a few months ago in my 2000 E39 with M52TU engine at 168K miles. While running, usually in city driving, after a stop at a red light etc, the engine would hesitate and choke, lose power with noticeable jerkiness, and then shut off once pulled over. The problem only occurred when the engine was warm, in fact, when the oil temperature reached to normal operating levels and not before that. It would happen during idle, as well as accelerating, but hardly on the highway.

The codes suggested both crankshaft sensors to be problematic (both intake and exhaust side), and burn failure in all six cylinders.

I replaced both crankshaft sensors with BMW ones. Problem remained. It very much seemed like an electrical issue, and not a crack in the intake hoses, i.e. unmetered air being introduced into the system.

Along the way of diagnosis, I cleaned the idle control valve, replaced all coils and spark plugs. The DISA valve was replaced not long ago. The problem still remained.

When I was watching "Nathan's DIY" YouTube channel --- A big thank you goes to Nathan ---, I heard him say that these M52TUs sometime cannot distinguish between crankshaft and camshaft sensor problems. So I decided to change the crankshaft sensor as a last resort.

When I took it out, I saw that there was motor oil in the connector that plugs into the crankshaft sensor. Cleaned it with MAF sensor cleaner and an air gun, put in the new OEM sensor, put everything back together, and the problem is solved.

I figured the ECU is indeed unable to tell whether the crankshaft or camshaft sensors are problematic, and in this case, since the oil is impeding the signal, it assumed the crankshaft signal to be the reference, which made it conclude that both camshaft sensors are off. But what are the chances of both sensors going bad at the same time? Long story short, if you have a similar issue, it might very well be your crankshaft sensor. It might be a good idea to check and perhaps replace it around 150K miles.

Last edited by aktansrt; 01-03-2018 at 11:15 AM.
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Old 01-03-2018, 12:14 PM
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Thanks for your experience.
Crankshaft sensor signal - as long as it is working - supposed to be a better reference since the camshaft angle is affected by the Vanos. And the camshaft gives a signal at every 180 degree turn while the crankshaft signal's resolution is around 5 degrees.

A single camshaft signal is not reliable for that reason. On later models the engine is able to run on both camshaft signals if the crankshaft fails. By monitoring both camshaft signals the Vanos operation can be calculated/confirmed, but this isn't a perfect solution since the only information is the time and the angle between the intake and exhaust, a differential value instead of an absolute angle of each.

ps: there is a typo in your post about intake/exhaust "crankshaft" sensors
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Old 01-03-2018, 12:18 PM
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here you can see the difference between the crankshaft (top) and the camshaft signal (bottom)
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Old 01-03-2018, 01:26 PM
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Quote:
Originally Posted by aktansrt View Post
---, I heard him say that these M52TUs sometime cannot distinguish between crankshaft and camshaft sensor problems.
This isnt something special to the bmw motor..

all motors.. will suffer the same..

cam crank and knock.. is all one big downstream single *inshort.

thats why the timing degree (so you know which way the motor is leaning)
and the secondary input from downstream... (letting you know how its reading)

its very very simple.. once you understand the language, Its elementary compare to PLC and logic controllers non the less.. it still has to preform with in its boundarys
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Old 01-03-2018, 02:36 PM
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Quite informative - thanks for posting.

What caused the oil in the connector? If memory is correct, the crankshaft sensor is below the starter, which doesn't seem like an area where oil typically pools up...Leaky oil filter housing gasket? Maybe a drip from the high side of the valve cover gasket?

I also like Nathan, but he does cut a lot of corners, and some repairs on cars (like valve cover and head gasket) seem to come back for a re-do with some frequency. He is also not likely to ever put 80-100k miles on any single car he owns. He gets credit, though, for digging in to these cars
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burn failure, camshaft sensor, city driving, crankshaft sensors, e39, m52tu, misfire, warm engine


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