[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 am also operating a bit blind - a good troubleshooting software would go a long way here? What should I get?