S65/S85 throttle actuators - electrical failure SOLVED

[X5-User]

Originally Posted by omniphil

Do you mean internally?

I have some race grease for my bike, I assume that would probably work good. It's used for clutch and brake levers and stuff like that.

They say that electronics can fail as well

[omniphil]

Originally Posted by Bimmer-M3

They say that electronics can fail as well

After reading this thread it sounds like the electronics fail because the plastic wears out and the motor keeps hunting around causing excess heat to the FETs ?

[thekurgan]

Originally Posted by omniphil

Do you mean internally?

I have some race grease for my bike, I assume that would probably work good. It's used for clutch and brake levers and stuff like that.

Externally, I found mine dry and squeaky, which probably doesn't help the motor function. It's an extremely hot area where they reside. Maybe copper-based anti-seize would help.

[omniphil]

Originally Posted by thekurgan

Externally, I found mine dry and squeaky, which probably doesn't help the motor function. It's an extremely hot area where they reside. Maybe copper-based anti-seize would help.

Tin foil heat shielding?

[spyderco10]

Crud, my car just threw all those errors codes and went into limp mode. It's probably the TVAs as well.

[omniphil]

Originally Posted by spyderco10

Crud, my car just threw all those errors codes and went into limp mode. It's probably the TVAs as well.

How many miles on your car?

[spyderco10]

Originally Posted by omniphil

How many miles on your car?

It's got only 25,000. I started it up again after work and all of the codes were gone. I just ordered the Bavarian Technic tool so I can verify what the codes were. Hopefully it's not the throttle actuator, but then what else could it be?

[pbonsalb]

The problem starts intermittently. Restarting the car usually works to eliminate the codes and limp home mode in the early stages of the problem. Usually TPS or actuator related. TPS tend to work or not work whereas TVA fail intermittently before failing every time.

[Powashiftin]

Got these codes on my car and engine stuttering under 1k by giving it throttle. Dealer said it was bank 1 actuator. Just got the TA today. Looking to do be DIY tomorrow...

[jester17]

I take it this is what causes our Ms to lurch violently in 1st, yes? Here's a question: The SA at my dealership says they want me to wait until I have a CEL before looking at the issue even though I've been having the lurching problem... do you all agree, or should they be addressing the situation now? The car's a 2009 with a 1-year warranty in effect for about another 11 months...

Thanks!

[alpina-527]

Originally Posted by jester17

I take it this is what causes our Ms to lurch violently in 1st, yes? Here's a question: The SA at my dealership says they want me to wait until I have a CEL before looking at the issue even though I've been having the lurching problem... do you all agree, or should they be addressing the situation now? The car's a 2009 with a 1-year warranty in effect for about another 11 months...

Thanks!

A worn actuator won't give you the lurching. If anything at all is wrong inside the actuator, it throws a fault code.

Using low grade fuel can cause lurching.

[jester17]

Originally Posted by alpina-527

A worn actuator won't give you the lurching. If anything at all is wrong inside the actuator, it throws a fault code.

Using low grade fuel can cause lurching.

Hmmm.... I've never put anything but 93 in it. Could it be anything else? Happens about half the time...?

[pbonsalb]

I get a lurching sometimes on cold starts. If I turn off the power button it usually goes away. Just occurs sometimes and only until the car has warmed up a little.

[Beemdog]

Lurching can be solved with your throttle/rpm control. Also, if you are having issues with lurching, you can step the "Power" mode down to the slowest throttle response setting, at least until the car warms up.

In my experience, any high HP or quick throttle response car with low gearing and no torque converter (to add in a little slip) will lurch if driven with the wrong kind of throttle foot. You should have seen my first week in a Viper! The jerking motion itself adds into the problem as it feeds back to your right leg. It's like head-shake (steering oscillation) on a motorcycle-- 85% of it is the rider himself as part of the feedback loop.

[spyderco10]

Yup, the codes came on again, seems pretty constant. Somebody's making money selling all these TAs to us.

[Dumpspec]

Originally Posted by Sean1933

I'm sure many of you are aware of, or experienced first hand, the common faults with the throttle actuators fitted to both of the above M3/M5 engines. I recently suffer this same failure and was determined not to path the stealers £800 each, especially when you really should be replacing both.

Many people are aware of the gear wearing issue and a couple of members have started to manufacture replacement gear sets which is awesome. However the secondary failure on quite a few actuators seems to be electrical, as many suspect, this being due to the backlash of the worn gears causing constant adjustment and overheating of the electrics. When this happens it seemed only a new replacement from BMW was the answer. Well I think I have cracked it.

My failure started when I was 60 miles from home so triggered I would try and get it home instead of waiting 3hrs for an AA low loader. Jerky throttle response followed by the eventual Christmas tree dashboard and error messages. The journey home was painful, but rather fun, as she hated cruising by WOT was fine . Having read the codes it registered P1628 being bank 1 throttle actuator. Once I was home, she was stuck permanently in limp mode and failed the pre-start actuator test. Following removal of both actuators I inspected and noted the gears were worn as many of us have come to find. Thinking this just meant I had to get the gears sorted I rotated the middle gear through 180degrees (less worn contact points) and refitted, hoping no codes would flag. No such luck, same code. I removed again and swapped the electrics over but left the main actuator bodies in their original positions - the only error then registered P161F being bank 2 throttle actuator, confirming the error had followed the board, not the gears. I removed both actuators for further inspection and found - you can see one of the MOSFET transistors is rather black:

https://www.dropbox.com/s/6ea8rpk62u...%2056.jpg?dl=0

I then removed the blown Fet using an iron and de-older braid:

https://www.dropbox.com/s/n0jfuq79kd...%2043.jpg?dl=0

Following lots of investigation I located a replacement source from the states, this is the part - each board has 5, so just I case the others were fried but I bought spares, 15 in total ( they cost £2 each inc postage):

https://www.dropbox.com/s/tez8wix9xb...%2033.jpg?dl=0
https://www.dropbox.com/s/1snj7mvju7...%2015.jpg?dl=0

And here is it fitted:
https://www.dropbox.com/s/49oac6syy0...%2001.jpg?dl=0

Following refitting, she started first time, no error code on pre-check Annandale no error when running for 10 mins ( with tests at various throttle positions). As a side note, these engines sound epic without the plenum fitted!!!

Plan now will be to get the gears changed for new ones, but all in all a massive result I feel. 2 new, 'improved actuators' for under half the price of 1 new one. RESULT.

anyone in bay area has tried this method? i currently have a defect throttle actuator in bank one. it is intermittent and only shows code once in awhile.

[s2kvee]

Originally Posted by dumpm3

anyone in bay area has tried this method? i currently have a defect throttle actuator in bank one. it is intermittent and only shows code once in awhile.

Me too... My car has been nothing but problems after problems... But then again that's what I get for getting mine from an auction... If u ever try this method.. Lmk, I'm in the Bay Area as well. I may possibly be taking out my actuator to inspect it.. Perhaps it's as simple as a $1 chip replacement..

[s2kvee]

Has anyone tried, rotating the gear or if possibly flipping the gear, as well as replace the chip? Ok noticed the OP stated he rotated the gear 180* to an area that's less worn, but that was before he had replaced the mosfet transistor...

[spyderco10]

OK, it's my throttle actuator, bank 2. Guess I'll be replacing it

[OverRev]

bank 2 is driver side or passenger side? cause my is bank 1 is causing problem and i wonder which side it is.

[bmwlover0725]

Originally Posted by OverRev

bank 2 is driver side or passenger side? cause my is bank 1 is causing problem and i wonder which side it is.

Bank 1 is passenger side. My bank 1 failed, but I replaced both. Next time this happens I'll just do a gear set. They weren't out when I did mine. I have a DIY video I made for this whole topic. I just haven't uploaded it yet.

[conscom]

Originally Posted by omniphil

It would seem like some good preventative maintenance would be to replace the gears early considering what the actuators cost.

I don't suppose there's a source to just get the stock plastic gears themselves?

Go to odometergears.com US$225 for 2 sets. You don't want to mate metal gears to plastic.