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  #1  
Old 05-25-2022, 12:50 PM
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E70 N52 Extended Cranking at Startup

Hey all, recently noticed that our 2010 X5 30i is exhibiting extended cranking times when first starting the car. Instead of the "push-button-one second-start" it's more like "push-button-three seconds-start".

This is concerning. No codes or engine light on yet. Has anyone experienced this with an N52?
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  #2  
Old 05-25-2022, 12:55 PM
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Do you have a scanner that will pull the battery level histogram? It's a very good way to get a sense of is the problem more related to the battery or the starter.

Typical starter failure presents with the symptom you describe. Just takes longer to start. A defect in the starter will cause it to take much more current. It drops the voltage from the battery getting less torque at the starter, lower RPM.

Get a current reading on the starter cable and a load test on the battery
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Old 05-26-2022, 12:11 PM
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Quote:
Originally Posted by andrewwynn View Post
Do you have a scanner that will pull the battery level histogram? It's a very good way to get a sense of is the problem more related to the battery or the starter.

Typical starter failure presents with the symptom you describe. Just takes longer to start. A defect in the starter will cause it to take much more current. It drops the voltage from the battery getting less torque at the starter, lower RPM.

Get a current reading on the starter cable and a load test on the battery
Interesting perspective. I'm thinking its likely fuel pump/regulator related. I can't see how this would be related to the starter at all, it is functioning perfectly.
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Old 05-27-2022, 09:17 AM
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E70 N52 Extended Cranking at Startup

"extended cranking" is the primary symptom of a failing starter. So "functioning perfectly" may be inaccurate (though it also could be accurate)

The same symptom also comes from a weak battery or a bad ground or as you surmise: bad fuel pump or FPR.

You can eliminate bad ground by measurement of the voltage from B- jump point under the hood to the engine block while starting. Should be millivolts not say over 0.2-3v.

Usually you can eliminate battery as the cause by a load test.

You can test your theory of fuel supply with the FPR being the most likely candidate of failure by an overnight fuel pressure test. Hook up a gauge to the fuel rail and test it to see if you get 50 psi. Then turn off the car it should drop quickly to ≈ 40-43 but very slowly drop over the next 8-12 hours. It should still read 10-20# overnight.

I am not sure on N52 (I think that's your motor) on the rail pressure it may have been changed since M54 I'm more familiar with but I don't think it uses the stupid high pressure like N55/63.

You can also measure the voltage across B- B+ jump points during starting. I haven't measured that value on my or wife's e70 yet but I could do that for a rough baseline. My customer has an N52 based 328xi I could also measure that value.

What causes the starter related slow crank is shorts in the winding that increase current while reducing torque=power. The increased current drops more voltage (often by as much as two volts) which dramatically drops the power even more. The starting rpm will drop and it takes more seconds for the same number of power strokes to get the car started.

It's more evident on diesels, you read about it very often but will happen on any car.

That said, it's just as likely to be a fuel supply issue so start with checking whatever is the easiest.

You can check the voltage drop from the cig lighter to B+ under the hood and multiply by 300 to get a rough estimate of current. My m54 used to produce 0.75v on a first attempt and 0.625v on a restart (within about a minute).

I haven't done that test on my n55 or wife's N63 but I could do that test on customer's n52 as soon as tonight/tomorrow for an N52 baseline.

One last thought re: fuel pump. They get weaker and weaker over time at end of life but their site demise is masked by the FPR so they seem to fail quickly though they usually fail over 6-12 months.

Ideally a test of pressure at the pump is best but it takes a lot more effort to do that test.

I would measure the current draw to the starter to eliminate that variable since it's rare one that bites people in the ass. (I've read at least 5-6 cases where people replaced their perfectly ok battery to discover 2-5 months later the exact slow crank returns because the problem was the starter pulling 300 vs. 200 amps.)

Take your odometer and divide by your OBC average speed eg 149000/27=5518.519.

If that number is over 5000 the pump is on borrowed time. That number above is close to my actual values meaning i probably should at the least measure my low pressure pump's output myself.
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Last edited by andrewwynn; 05-27-2022 at 09:27 AM.
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Old 05-27-2022, 11:41 PM
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Quote:
Originally Posted by richardb View Post
Interesting perspective. I'm thinking its likely fuel pump/regulator related. I can't see how this would be related to the starter at all, it is functioning perfectly.

I haven't had to do fuel supply repair on the e70 yet. I forgot it uses an electronic module to control the pump. I don't know if that is just the equivalent of a fancy relay or does it work like Ford and I'm sure other cars and uses PWM or such to actually control the output pressure from the pump or does it use a spring FPR in the filter like the e53.
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Old 05-28-2022, 01:21 PM
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Thanks for the additional detailed comments! Appreciate it.

Some deep Googling shows the fuel pressure drop overnight issue like you described, I think this part is prone to developing a crack that relieves the pressure in the FPR part:

https://www.fcpeuro.com/products/bmw...ly-16117195469

There's also the main fuel pump:

https://www.fcpeuro.com/products/bmw...ly-16117195463

To be honest I'm not sure which side the fuel pressure regulator lives on. RealOEM doesn't describe it. Also, I've not seen a fuel filter anywhere on RealOEM or FCP Euro or the other shops.

Does the N52 E70 have no fuel filter? Weird.

Also just to note, the battery is new. Made a video on that here: https://youtu.be/sFIW61jRP4k
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Old 05-28-2022, 01:35 PM
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Just about to roll over 92,000 miles on the odometer! Current MPG on the computer has dropped significantly lately, showing 15.8 MPG. Next job is replacing the faulty DISA under the intake manifold, not sure how much this contributes to the poor MPG.

On an unrelated note, the "seat calibration" warning started coming up the other week. So perhaps the seat module is toast and not "going to sleep".

The problems just keep on coming, from the ultimate driving machine.

Last edited by richardb; 05-28-2022 at 02:13 PM.
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Old 05-28-2022, 02:12 PM
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Charging status histogram (battery)
Time with state of charge in range:

0-20% 0h
20-40% 0h
40-60% 0h
60-80% 0h
80-100% 758h

From a Foxwell NT510 Elite
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Old 05-29-2022, 10:05 AM
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Similar starting issue culprit for me was a fuel pump relay. It wouldn’t start the first time on cold or hot days.
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  #10  
Old 06-19-2022, 09:41 AM
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Quote:
Originally Posted by andrewwynn View Post
"extended cranking" is the primary symptom of a failing starter.
Couldn't agree more. Happened to me recently in the E70 3.0si, the starter fail3d totally at the most unexpected and inappropriate timing. So better have it repaired or replaced asap.

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