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Greenfingers

Throttle actuator gone bad

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For a few weeks now, I've noticed a noise that happens for about 3 seconds after switching the engine off. I had assumed it meant time for another new suspension bag, because it sounded like the air compressor was kicking in, although the car hasn't been dropping at all lately. Yesterday I thought to verify this by removing the fuse for the compressor and to my surprise discovered that the noise still happened each time the engine was switched off.

 

Then I realised that it seemed to be coming from the front of the car and after opening the bonnet and getting my daughter to switch the engine off, it became clear it was coming from the inlet manifold area. It sounds a bit like a solenoid switching on and of about 10 times per second, but more of a metallic clattering and quite alarmingly loud. Googling and searching on here hasn't brought up many suggestions, other than it could be related the throttle or swirl flaps, since they are active in the shut down process.

 

So I have just tried pulling off the electrical connector on the throttle body and lo and behold the noise has gone! Presumably, either the throttle valve itself has partially seized, or the gears are worn to the point of slipping. I'm relieved to know it's not swirl flap related, but surprised at the scarcity of reports on the web of similar occurrences.

 

Has anyone here had the same issue, or even had cause to dismantle their throttle body? It's raining outside atm, so I haven't started to strip it down yet and don't know whether it will be an easy fix or best to buy a replacement.

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Still raining, so I haven't tried dismantling yet. After doing some reading, I now wonder if this might actually be an electrical problem, rather than mechanical.

 

It seems there is a sensor in the unit which detects the position of the throttle plate. The car doesn't misbehave at all when driving or idling - just this sound (like gears slipping) for 3 or 4 seconds after switching off. Perhaps the problem is related to a faulty or missing signal from the position sensor? Having found some instructions on the web for doing a throttle reset, I tried pressing the accelerator down for 30 secs with ignition on and then pressing ignition again, but no joy.

 

The engine stops normally with no shuddering, which makes me think the throttle must be closing properly, so could it be that the components are all working fine, but the motor tries to keep running after closing the throttle because it doesn't get the signal to stop? I am guessing there must be an override which stops it after a few seconds to protect the motor etc.

 

I bet Matthew will have an idea about this.

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Sure this is normal, if my memory serves me right egr makes the noises ( if its same thing your on about ) just before you go dismantling things have another Google search. 

Edited by marko530d

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Thanks Marco. Yes, sure there are some normal noises, but this is new and loud (you would easily hear it from the other side of the road). It sounds a bit like a hammer drill!

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2 hours ago, Greenfingers said:

Thanks Marco. Yes, sure there are some normal noises, but this is new and loud (you would easily hear it from the other side of the road). It sounds a bit like a hammer drill!

Ah maybe upload a video, see if anyone can help you out buddy. 

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Get the codes read, if it is an error it'll flag up.  It (the throttle valve) will also prevent the car doing a DPF regen too, so it's best to get it sorted out sooner rather than later. 

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1 hour ago, dj1233 said:

Get the codes read, if it is an error it'll flag up.  It (the throttle valve) will also prevent the car doing a DPF regen too, so it's best to get it sorted out sooner rather than later. 

 

Thanks dj - my cheapo 'Autel' diagnostic tool doesn't detect anything and yes, I'm also aware that restricting the air supply is an important factor in raising the temperature to facilitate DPF regenerations.

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1 hour ago, IINexusII said:

If its like this then its normal

 

 

 

1 hour ago, IINexusII said:

If its like this then its normal

 

 

 

1 hour ago, IINexusII said:

If its like this then its normal

 

Yes Nexus, that sounds familiar. I believe it is something to do with the swirl flaps and purging of residual pressure on shutdown.

 

This sounds different and much louder - I will try to upload a video tomorrow.

 

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Okay, so I've just done my first ever Youtube video! Two actually.

 

The first one is with the electrical plug disconnected from the throttle body and shows what I understand to be a normal engine shutdown:-

 

 

The second one is with the throttle plug connected and demonstrates the issue:-

 

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4 minutes ago, Greenfingers said:

So having just dismantled the throttle, this is what I found:-

 

 


Well done for stripping it down and finding the cause. It’ll probably need a new throttle body though which is a real shame just for a couple of damaged cogs. 

Edited by Matthew Ashton

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Yes agreed good job on stripdown, how many miles and what age is your car if you dont mind me asking?

As far as I am aware the throttle (Diesel) is only used to shut the engine down, so once per drive cycle it opens at key on and closes at key off.

Edited by percha

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Yes, the two worn gears are obviously the problem and in particular, the wear on the small driving gear. It looks like the throttle hasn't been closing properly for some time, so I think it's time to find a replacement ASAP. If I had a 3D printer, I would try to reproduce the white gearwheel instead of having to fork out £100s. You would have thought that if the gear on the motor is made of brass (and showing no signs of wear), the others should be too. Old school BMWs wouldn't have used soft plastic like that and it's a shame to see such built in obsolescence on these modern cars.

 

It's only done 123k miles Percha. The shutdown doesn't seem affected, other than the racket it makes, but my concern is the inability to restrict airflow, which helps increase combustion temperature to assist DPF regens. The crescent gear does show more wear at a partially open position, so there must be a reason for this.

 

Anyway, it's back together and running again now, so wasn't too tricky to get to.

 

Matthew, do you know if a replacement will need coding or not? I'm hoping that the foot pedal trick will set the position sensor and that is all that's needed, but don't want to have a non runner if I replace it myself on the drive!

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32 minutes ago, Greenfingers said:

Yes, the two worn gears are obviously the problem and in particular, the wear on the small driving gear. It looks like the throttle hasn't been closing properly for some time, so I think it's time to find a replacement ASAP. If I had a 3D printer, I would try to reproduce the white gearwheel instead of having to fork out £100s. You would have thought that if the gear on the motor is made of brass (and showing no signs of wear), the others should be too. Old school BMWs wouldn't have used soft plastic like that and it's a shame to see such built in obsolescence on these modern cars.

 

It's only done 123k miles Percha. The shutdown doesn't seem affected, other than the racket it makes, but my concern is the inability to restrict airflow, which helps increase combustion temperature to assist DPF regens. The crescent gear does show more wear at a partially open position, so there must be a reason for this.

 

Anyway, it's back together and running again now, so wasn't too tricky to get to.

 

Matthew, do you know if a replacement will need coding or not? I'm hoping that the foot pedal trick will set the position sensor and that is all that's needed, but don't want to have a non runner if I replace it myself on the drive!

 

As has been said, no coding required:

 

Removing and installing/sealing throttle body (N57 D30 U/O/T 0)

1R6h4m3 Important!
Read and comply with notes on protection against damage from electrostatic discharge (ESD protection).
1Ly5z2h Necessary preliminary tasks:
1KeKxk7h Unlock and disconnect plug (1) on throttle valve assembly.
1KfAi0eq Note:

For purposes of clarity, the intake plenum is shown removed.

Release screws (1) on throttle valve assembly.

Tightening torque 13 54 1AZ.

Remove throttle valve assembly.

1KhlCBvv Installation note:
Release sealing ring (1) on intake plenum.
1Jvu2xy Installation note:

Check stored fault message.

Delete fault memory.

 

Edited by Matthew Ashton

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It is also used during the DPF regeneration phase and prevents the diesel engine from overrunning:

 

Throttle actuator

The electromotive throttle actuator is secured to the intake plenum.

A throttle valve is necessary for all diesel engines equipped with a particulate filter system. The throttle valve chokes the intake air to ensure that the necessary increased exhaust-gas temperatures required for regeneration of the particulate filter are reached.

The throttle-valve actuator closes when the engine is switched off. This counteracts the engine's tendency to vibrate during the shutdown phase.

Yet another function is preventing the engine from overrevving. When the DDE Digital Diesel Electronics system detects increases in engine speed although no corresponding rises in the injection quantity have occurred, it responds by closing the throttle valve to limit engine speed.

Functional description

The DDE control unit opens and closes the throttle valve actuator electrically. The throttle valve's precise current position must be registered at all times to as a condition for optimal control. This function is discharged by the throttle-valve sensor, which provides contactless monitoring of the throttle valve's position within the throttle-valve actuator.

FsLTRfUl

Item Explanation Item Explanation
1 Throttle actuator 2 Throttle valve
3 five-pin plug connection    

When no power is being applied spring force holds the throttle valve open within the throttle-valve actuator.

Structure and inner electrical connection

The servo-motor employed to adjust the position of the throttle valve is a DC motor. The throttle-valve sensor is a Hall-effect device. The hall effect sensor determines the revolutions of the servomotor. This provides the basis for calculating the position of the throttle valve.

FsNmynJu

Item Explanation Item Explanation
1 Throttle-valve actuator with throttle valve 2 Hall effect sensor
3 Electronic component with evaluation electronics    

Pin assignments

Pin Explanation
SIG1 Positive connection for controlling activation of throttle-valve actuator
SIG2 Negative connection for controlling activation of the throttle-valve actuator
5 V Voltage supply for throttle valve sensor
Terminal 31E Terminal 31E, electronics earth, throttle valve sensor
SIG3 Throttle-valve sensor signal

Signal shape and setpoint values

The DDE furnishes the 5-volt power and the earth connection for the throttle-valve actuator.

A bridge circuit (H bridge) is used to activate the servomotor. This permits activation of the servomotor in the opposite direction. The bridge circuit is monitored diagnostically. H-bridge designates an electrical gearshift with 5 shift elements in the shape of a capital H for shifting between.

FuvSPD9D

Item Explanation Item Explanation
1 Throttle-valve position in % 2 "Maximum" characteristic curve
3 "Minimum" characteristic curve 4 Throttle-valve aperture in degrees

Please note the following specifications for the throttle-valve actuator:

Variable Value
Servomotor supply voltage 5 Volts
Activation frequency for servomotor 1300 Hz
Blocking current for servomotor 4 A
Electrical power supply for throttle-valve sensor 4.5 to 5.5 V
Current draw of throttle-valve sensor 10 mA
Operating temperature range for throttle-valve sensor and servo-motor -40 °C to 140 °C

Diagnosis instructions

Failure of the component

Should the throttle-valve sensor fail the following symptoms can be expected:

  • Fault entry in the engine control unit
  • Emergency operation with substitute value (limited engine torque)
  • Check Control message

If the servomotor fails, the following behaviour is to be expected:

  • Fault entry in the engine control unit
  • The throttle-valve assumes its mechanical emergency-air position
  • Check Control message

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Looks like this is the part number: 13547806231 £354 list from BMW but available as an OEM unit much cheaper than that.

 

Make sure you buy the relevant seals as well: 11617801943 and 11618506786

 

 

Edited by Matthew Ashton

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23 minutes ago, Matthew Ashton said:

Looks like this is the part number: 13547806231 £354 list from BMW but available as an OEM unit much cheaper than that.

 

 

Thanks for all the information! That part number is exactly correct and the cheapest aftermarket part I can find is about £200 - it's probably what one would expect, but poor value for a diy fixer like myself. I've already found a brass gearwheel in china with the same number of teeth and am very tempted to give it a try for £15, but it would take a few weeks to get here and no guarantee it will work. I would buy a used part if it was fit for purpose, but if mine failed after 120k miles, that seems like a bad idea.

 

I'm surprised to see so few reports of similar failures. There must be plenty of higher mileage cars than mine around, so why haven't more people had the same problem?

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https://www.ebay.co.uk/itm/Control-Flap-Air-Supply-Luftregelventil-Cog-For-BMW-X5-X6-3er-5er-7er-/114355121160?_trksid=p2349624.m46890.l49286

 

What about this repair kit, comes from Germany.

 

Replacement cogs are metal.

 

Edited by marko530d

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10 minutes ago, marko530d said:

 

Thank you Marko, I did see that kit and believe it would work. It's not super cheap and it would be easier to buy a new unit, but I started wondering when I found this :-

 

https://www.ebay.co.uk/itm/Throttle-Body-Spacer-Auto-Car-Throttle-Body-Repair-Kit-With-Gear-Gear-Part-Screw/393069872475

 

I know I'm a cheapskate, but only when it makes sense!

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It's almost funny when you realise that almost all of these parts are made cheaply in China, but some of us unwittingly end up paying many times the price for the same components, because they are supposedly produced by a bona fide company in Europe!

 

I never ever subscribed to the old addage 'you get what you pay for'. OEM BMW parts are more like 'fools gold'!

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14 minutes ago, Greenfingers said:

 

Thank you Marko, I did see that kit and believe it would work. It's not super cheap and it would be easier to buy a new unit, but I started wondering when I found this :-

 

https://www.ebay.co.uk/itm/Throttle-Body-Spacer-Auto-Car-Throttle-Body-Repair-Kit-With-Gear-Gear-Part-Screw/393069872475

 

I know I'm a cheapskate, but only when it makes sense!

:lol::lol:

 

That 1 dont state it fits N57.

 

Even second hand units are around £100.

 

Nothing wrong with repairing rather then replacing buddy.

 

 

https://www.ebay.co.uk/itm/Control-Valve-Air-Supply-Air-Control-Valve-Gear-for-BMW-x5-x6-3er-5er-7er-/163427622368?_trksid=p2349624.m46890.l49286

 

This ones a tad cheaper.

Edited by marko530d

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Just now, marko530d said:

:lol::lol:

 

That 1 dont state it fits N57

 

I know, but that's exactly my point. Look at the picture and count the number of teeth on the gears, then decide if it is actually the same part.

 

That part will probably work as a replacement for hundreds of different model numbers. It's all about economy of scale for the producers and car companies. Why would you design a new part specially for 1 model of car, when there are already millions of products already available that would work?

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