I may have induced a problem with my Throttles - how to debug?

[eswaroop]

Ok, long story on my 09 M3.. Car was running fine, but coming up on 54k miles. Wanted to rebuild the TA's ahead of complete failure, so took the risk of taking them out and swapping out the gears.

Got myself a pair of used TA's (with at least one known bad one) to first learn how to rebuild the TA's and swapped out the gears myself on that pair first.

When I pulled my TA's instead of then rebuilding my own pair, I used the mechanicals(gear and spring assembly, the bottom part of the TA's except the boards) from the set I found used, and paired them with the good boards on my original TA's (probably first mistake) - tested the motors on both to be at least operational.. Put everything back together and car ran fine for at least a 1000 miles.


Now I got a little greedy I guess as I had read the TA linkages may be stiffening up and eventually cause the gears to fail, so decided to open the car back up to clean and lube them.. This is when things started going south.

When I lubed the throttle linkages. first I lubed bank 2, I used a penetrating lubricant (Wurth HHS-K) - the bank seemed to get a lot smoother and easier to operate the valves (at least by hand). But after a few minutes, I realized that this lubricant is also somewhat adhesive like when it dries, and gets a unique adhesive like consistency.. Anyways I panicked and did not use the same lube on Bank 1, instead opted for a different lube (penetrating lithium grease). Bank 2 got smoother as well, but was slightly stiffer - not as easy as bank 1 to operate.

Also when I was lubing the linkages, I moved the shafts longitudinally a bit to loosen them up (and possibly hurt the TA sensors? Not sure)

Anyway, I put everything back together, fired the car up and started getting error codes.. the same ones someone gets when a TA goes bad.. Bank 1 started failing pre-drive check at least once but then I turned off and started the car and unfortunately it went into limp mode.. I turned off the car, cleared the codes thinking maybe the linkage position was not calibrated and so reset codes, and restarted the car. Luckily, no codes appeared, so I assumed the error was a fluke and that all was good and put everything back together. Car drove fine for about 100 miles but then went into limp mode when driving today. Both bank 1 and bank 2 gave me errors.

Bank 1 - failed pre-drive check 2B21
Bank 2 - 2B16

Guess I panicked again, as I thought the mechanicals I used from the other set may be faulty, So I pulled out the TA's, rebuilt the original mechanicals of the TA's I had on the car with new gears, and put the TA's back on (essentially, back to original TA's with new gears) - And as my bad luck would have it, same errors still appeared

Bank 1 - failed pre-drive check 2B21
Bank 2 - 2B16

I almost gave up hope, but I tried one last step and swapped out bank 2 TA board for one from the used set I got and put everything back together.

The faults cleared and I was able to start her up normally once. But now I was weary with the intermittent nature of this whole exercise, so let her cool off and waited to try and re-test.

Sure enough, try to cycle again (No engine start, just power on to initiate the pre-drive checks and bank 1 fails pre-drive check)

Bottom line, I have one or more possible failure modes.

1) One ore more of the TA's are bad
2) Bank 1 is failing pre-drive check.

I am struggling a bit to decipher if the bad TA's are causing the bank 1 pre-drive check fail or if the tighter linkage is causing the check to fail.

What are my options forward? I am a bit worried that repeated pulling of the TA's may cause further induced failures eventually (bad connectors etc)

I could get a new set of TA's and swap them out to at least eliminate that possiblity of bad TA's but I doubt if it will fix the problem.

I am worried that the tighter linkage on bank 1 could cause the new TA's to fail prematurely.. Maybe try lubing it again until I can get it somewhat close to Bank 2? (I already tried cleaning it out and re-lubing, no luck)

Thoughts? Ideas? ( I posted the same on the TA thread as well but hoping this will drive some additional attention as the issue may be beyond just the actuators)

[pbonsalb]

If the banks don’t read the same, there is a problem. If one side is stickier that could be an issue.

[eswaroop]

Originally Posted by pbonsalb

If the banks don’t read the same, there is a problem. If one side is stickier that could be an issue.

Thanks, thats what I was thinking as well. I bit the bullet and used the same HHS-K lube generously on bank 1 yesterday, seems to have loosened it up. Cleared the faults and hooked everything back up - she's running fine so far (50 miles in, multiple start stops, no codes - ...yet.)

I hooked up the diagnostics reader and watched the TA actual % open data - bank 1 seems to oscillate at idle from a 0.2% to 0%, sometimes even -0.1%

Bank 2 seems to hold stable at idle at 0%

Have to drive it really hard for TA's to really open up - flooring the pedals gets me to about 85% - 89% on both banks regular driving (2k - 3k rpm range) - they barely open, to about 5-10% Not sure if that's normal..

[randrews15]

I've never heard of anyone living the linkages on the TAs. I'm not sure what that may of done other than put a lubricant in an area that it wasn't meant for. You're in a tough spot and it will be interesting to see how it resolves itself.

[eswaroop]

Originally Posted by randrews15

I've never heard of anyone living the linkages on the TAs. I'm not sure what that may of done other than put a lubricant in an area that it wasn't meant for. You're in a tough spot and it will be interesting to see how it resolves itself.

Sticky situation to say the least.. Attached a picture of the areas that I cleaned dirt / debris and lubricated.. Picture is not from my car, just sample I downloaded.

[randrews15]

Originally Posted by eswaroop

Sticky situation to say the least.. Attached a picture of the areas that I cleaned dirt / debris and lubricated.. Picture is not from my car, just sample I downloaded.

I wonder if some BMW techs on here can chime in and offer some insight. I'm really curious as what the solution will be.

[SAMM3Y]

Just to confirm when you rebuilt the TA's you wound the spring once and made sure the pins for actuator motor to the ECM fully engaged? I'd check those pins make sure they're nice and tight..

[eswaroop]

Originally Posted by SAMM3Y

Just to confirm when you rebuilt the TA's you wound the spring once and made sure the pins for actuator motor to the ECM fully engaged? I'd check those pins make sure they're nice and tight..

Yes, wound the spring once - how do I make the pins tight? maybe there's a way to nudge the clips on the board.. I did notice they progressively got a bit loose the more times I swapped the boards around..

The wound spring does sit a tad lower than when I first opened them up - not sure why, because I kept track of how much it unwound when I opened them first and then wound it back the same way..

[SAMM3Y]

Originally Posted by eswaroop

Yes, wound the spring once - how do I make the pins tight? maybe there's a way to nudge the clips on the board.. I did notice they progressively got a bit loose the more times I swapped the boards around..

The wound spring does sit a tad lower than when I first opened them up - not sure why, because I kept track of how much it unwound when I opened them first and then wound it back the same way..

You can squeeze the plastic terminal housing with a pair of needle nose on the ecm gently to tighten up the connection or slightly bend the pins to make sure they're making good contact. As long as the gear isn't fouling inside the actuator it shouldn't be an issue. I actually felt mine sat higher than the previous. How does the assembly look and feel when you exercise it when it's assembled and installed with the throttle linkage?

[eswaroop]

Originally Posted by SAMM3Y

You can squeeze the plastic terminal housing with a pair of needle nose on the ecm gently to tighten up the connection or slightly bend the pins to make sure they're making good contact. As long as the gear isn't fouling inside the actuator it shouldn't be an issue. I actually felt mine sat higher than the previous. How does the assembly look and feel when you exercise it when it's assembled and installed with the throttle linkage?

Will try this if I get the limp mode again. Before I installed them back, checked for smooth operation, they seemed fine. One of them did have a slight rubbing noise which seemed like the motor brush(es) (Presume these are brushed motors?)

[SAMM3Y]

Originally Posted by eswaroop

Will try this if I get the limp mode again. Before I installed them back, checked for smooth operation, they seemed fine. One of them did have a slight rubbing noise which seemed like the motor brush(es) (Presume these are brushed motors?)

No I believe they are brushless motors with multiple hall sensors that's how they determine position.. if you hand turn the motors without any gears in the actuator it spins very freely..

[eswaroop]

Originally Posted by SAMM3Y

No I believe they are brushless motors with multiple hall sensors that's how they determine position.. if you hand turn the motors without any gears in the actuator it spins very freely..

Ah - I might have a new gear that's fouling just slightly with the covering plate then.. Darn!

Might be worth doing a DIY walking first timers through how to properly rebuild an actuator (At least the gear portion to begin with and maybe the mosfets and other components too for those who venture) - There were some videos on youtube for the gear replacement I followed but they left out the pitfalls to watch out for I guess..

Might explain why it may fail after a prolonged heat episode - the components expand.. possibly forcing the gear mechanism to seize.

[eswaroop]

Originally Posted by eswaroop

Yes, wound the spring once - how do I make the pins tight? maybe there's a way to nudge the clips on the board.. I did notice they progressively got a bit loose the more times I swapped the boards around..

The wound spring does sit a tad lower than when I first opened them up - not sure why, because I kept track of how much it unwound when I opened them first and then wound it back the same way..

See how the spring seats ( seems tad lower than the original in the well doesnt it? )

This picture is from the practice rebuild

[eswaroop]

Found something else very interesting on closer inspection of the practice build - the new center full gear has more play than the old center gear! ( Both tested with new half gear in place )
Makes me question the effectiveness of the new set of gears ! These were from a company called Tafmet from Poland

[randrews15]

Originally Posted by eswaroop

Found something else very interesting on closer inspection of the practice build - the new center full gear has more play than the old center gear! ( Both tested with new half gear in place )
Makes me question the effectiveness of the new set of gears ! These were from a company called Tafmet from Poland

Not to be mean, but when were the Polish revered for their engineering and craftsmanship. Just saying....

[mapster37]

best thing to do at this point: close the hood. put all parts in a box and tow it to a professional....

[SAMM3Y]

I used the gears from the UK, can't remember the brand but was very impressed with the quality..

[roastbeef]

Originally Posted by mapster37

best thing to do at this point: close the hood. put all parts in a box and tow it to a professional....

this.

car was fine until you decided to be proactive. its been said on here you don't need to lubricate these as most lubricants attract dust. sounds like a perpetual chasing of problems created by the op.

[eswaroop]

Originally Posted by roastbeef

this.

car was fine until you decided to be proactive. its been said on here you don't need to lubricate these as most lubricants attract dust. sounds like a perpetual chasing of problems created by the op.

Don't fix something that ain't broken.. true - Should have snapped some pictures of before but the linkages especially on bank 1 were just covered in dust and grit and very tight / squeaky to operate..

What's done is done - the lube does seem to have helped and the car is driving great so far

Seems like the throttle adaptation algorithm may be taking it's time to normalize to the new configuration - the TA response curves were very sharp earlier but the readings are smoothing out now - let's see how she perks up..

May clean out dust that collects over next couple of months and just maintain her a bit better - will also get a sense of the dust issue.

[RHORD1]

You do know BMW has extended the warranty on the throttle actuators 10year/120000 miles. Not all but some. I could tell you if you gave me the last 7 of your vin.

[eswaroop]

Originally Posted by RHORD1

You do know BMW has extended the warranty on the throttle actuators 10year/120000 miles. Not all but some. I could tell you if you gave me the last 7 of your vin.

P361585

Did not know that - heard about the idle actuator warranty though

[alefcole]

Originally Posted by RHORD1

You do know BMW has extended the warranty on the throttle actuators 10year/120000 miles. Not all but some. I could tell you if you gave me the last 7 of your vin.

Please let me know

E368142

Do you have link, document?