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Steve
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Category: BMW
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Experience:  BMW Expert
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BMW 523i: I have a BMW 523i E39 1998 M52 Engine. Sympoms were,

Resolved Question:

I have a BMW 523i E39 1998 M52 Engine. Sympoms were, cutting out when stationary and when hot. I have replaced the Dual Temp Sensor, the Cam shaft position sensor and the Crank shaft position sensor. The MAF was replaced last year. The cutting out when hot has stopped so I guess the Dual temp sensor fixed that fault but the car is now very down on power in the midrange and if I look at the rev counter whilst trying to accelerate in 3rd gear or upwards it "jerks" rather than moves up smoothly. Also the idle seems to be a bit low....6kish rpm, not sure if this is related. Any ideas please
Submitted: 5 years ago.
Category: BMW
Expert:  Steve replied 5 years ago.

Hello and welcome to JustAnswer BMW,

My name is XXXXX XXXXX it will be my pleasure to assist you today.
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How many miles on the car?

Customer: replied 5 years ago.
125000
Expert:  Steve replied 5 years ago.

Thanks,

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I suggest you check fuel pressure to make sure it is adequate (50psi).

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Also this sounds like it might be a clogged catalytic converter - so this is another avenue to pursue.

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Also, if you are able to have a diagnostic done that can read live data that would also be very helpful in helping to run down any vaules that are out of alignment.

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I hope that is helpful. Please let me know if I can be of any further assistance, or clarify anything for you.

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It was my pleasure to help today, and I wish you the best with your repair and with your vehicle going forward.

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Many thanks,

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Steve

Customer: replied 5 years ago.
Steve,

If it is any of the above are they simple (cheap) fixes or expensive.

If fuel pressure is low how ease to fix?

If Cat blocked is does this mean a new exhaust

If valves out of alignment can they be re-aligned and at what cost

Expert:  Steve replied 5 years ago.

A blocked cat can sometimes be cleared out. You can also install aftermarket cats for not that much (few hundred).

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Fuel pressue would be either the pressure regulator or fuel pump, neither is very expensive.

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If its a valve problem it would be considerably more expensive - 800 to 1000 I would estimate.

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Please let me know if you have further questions.

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Many thanks,

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Steve

Steve and other BMW Specialists are ready to help you
Customer: replied 5 years ago.
ok...can you explain the erratic rev counter.....it gets to say 3krpm in 3rd then when I accelerate the rev counter "jumps" up to say 4.5krpm then seems to stick there then moves on which is why I was thinking more elctronic than mechanical fault.....last one promise....will hit accept after this...

Cheers
Expert:  Steve replied 5 years ago.
Any of the above could possibly cause it. Could also be engine computer related, but that would be very unusual. The best way to determine with certainty will be a scan that reads live data. Hope that helps. Please do not forget to press the green accept button on my post above. Thanks. Steve

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