Throttle Actuator Circuit Fix (Possibly)

pubo · 09-05-2018, 12:08 AM

Okay here goes. After months of procrastination, I've finally got my arse off to write this fix for these morbidly expensive actuator units. Got most of my info to start off from here, hence I'd thought it'll be fair for me to share it since I'm not planning to capitalize on the information. Credits to the existing threads for proper disassembles and preliminary troubleshooting.

To take the damn things off, refer to
http://www.m3post.com/forums/showthread.php?t=735033

As for the circuit fix refer to this thread
http://www.m3post.com/forums/showthread.php?t=1068709

The critical point would be to replace the mosfets with one which performs better than the HUFA76429D3ST_F085T-ND which is mentioned in the thread above. I'm using AUIRFR2905Z on both actuators, 5 per actuator.

View post on imgur.com

The parameter to look out for (besides the usual package size, voltage rating, current rating, vgs threshold voltage etc) would be the Reverse Recovered Charge of the Mosfet's body diode. And yes, this FET is automotive qualified as per AEC-Q101 as well.

HUFA76429D3ST

View post on imgur.com

AUIRFR2905Z

View post on imgur.com

The whole issue with people replacing them mosfets and having only some slight chance of rectifying the actuator's circuit issue would be the replacement mostet's revese recovery response isn't acting fast enough to prevent the backlash from the DC motor of the throttle actuator. This in turn causes the throttle actuators jerk on the de-energising phase of the actuator which would cause the self test to fail on startup. From my tests any mosfet with reverse recovery QRR of less than 50nC works fine with our modules. I have only ever tested with 6 units of throttle actuators, 2 of them from my own car so do take note of that.

I've used a pair of the fixed unit on my e90 for about a year now without any issues whatsoever. Swapped out the worned oem gears with i6 automotive replacement gears. Usual disclaimer, you're going to have to do this fix on your own risk yada yada yada. Hope this will be of some help to another owner who isn't prepared to fork out thousands for a replacement unit. The END

blk33 · 04-29-2022, 11:55 PM

Hi Pubo
I'm wondering if you had success with the MOSFETs AUIRFR2905Z in the throttle actuators?

Regards
Rob

ertech · 10-24-2022, 10:08 AM

did you end up using AUIRFR2905Z?

thanks

09-05-2018, 12:08 AM	#1
pubo New Member 3 Rep 18 Posts Drives: E90 M3 Join Date: Jan 2016 Location: Sydney iTrader: (0)	Throttle Actuator Circuit Fix (Possibly) Okay here goes. After months of procrastination, I've finally got my arse off to write this fix for these morbidly expensive actuator units. Got most of my info to start off from here, hence I'd thought it'll be fair for me to share it since I'm not planning to capitalize on the information. Credits to the existing threads for proper disassembles and preliminary troubleshooting. To take the damn things off, refer to http://www.m3post.com/forums/showthread.php?t=735033 As for the circuit fix refer to this thread http://www.m3post.com/forums/showthread.php?t=1068709 The critical point would be to replace the mosfets with one which performs better than the HUFA76429D3ST_F085T-ND which is mentioned in the thread above. I'm using AUIRFR2905Z on both actuators, 5 per actuator. View post on imgur.com The parameter to look out for (besides the usual package size, voltage rating, current rating, vgs threshold voltage etc) would be the Reverse Recovered Charge of the Mosfet's body diode. And yes, this FET is automotive qualified as per AEC-Q101 as well. HUFA76429D3ST View post on imgur.com AUIRFR2905Z View post on imgur.com The whole issue with people replacing them mosfets and having only some slight chance of rectifying the actuator's circuit issue would be the replacement mostet's revese recovery response isn't acting fast enough to prevent the backlash from the DC motor of the throttle actuator. This in turn causes the throttle actuators jerk on the de-energising phase of the actuator which would cause the self test to fail on startup. From my tests any mosfet with reverse recovery QRR of less than 50nC works fine with our modules. I have only ever tested with 6 units of throttle actuators, 2 of them from my own car so do take note of that. I've used a pair of the fixed unit on my e90 for about a year now without any issues whatsoever. Swapped out the worned oem gears with i6 automotive replacement gears. Usual disclaimer, you're going to have to do this fix on your own risk yada yada yada. Hope this will be of some help to another owner who isn't prepared to fork out thousands for a replacement unit. The END Last edited by pubo; 09-05-2018 at 12:20 AM..
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04-29-2022, 11:55 PM	#2
blk33 Enlisted Member 5 Rep 39 Posts Drives: 2009 E92 M3 Join Date: Aug 2020 Location: Geelong iTrader: (0)	Hi Pubo I'm wondering if you had success with the MOSFETs AUIRFR2905Z in the throttle actuators? Regards Rob
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10-24-2022, 10:08 AM	#3
ertech New Member 0 Rep 7 Posts Drives: bmw 2009 M3 Join Date: Oct 2022 Location: montreal iTrader: (0)	did you end up using AUIRFR2905Z? thanks
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