Bimmerfest - BMW Forums - View Single Post - 01 740iL Transmission problem
View Single Post
Old 08-29-2009, 12:26 AM
LAJoshua LAJoshua is offline
Registered User
Location: Sebastopol, CA
Join Date: Aug 2009
Posts: 1
Send a message via Yahoo to LAJoshua
Mein Auto: 2000 740i Sport
Hi everyone,

Hope I can help. This will be a little long-winded, but hopefully helpful so bear with me. I bought my 2000 740i Sport last July. Not 10 miles from the guy I bought it from I was in stop and go traffic waiting to go through a bridge toll booth and after stopping I noticed my car was very sluggish to pull up to the booth. Same when I was pulling out. I noticed on the dash a transmission failsafe warning aka limp mode. Not knowing what this is since I had never owned a BMW before, I drove it all the way home this way.

I actually pulled over at one point to get some tape because my left front turn signal popped out of its holder. Great way to start eh? Turned out one of the clips was busted and just needed to replace the signal. Sadly I had turned off the car, but did not take the key out of the ignition. I later found out that when the car goes into failsafe mode you need to pull over immediately and take the key out of the ignition and then restart. This resets the tranny computer. It does not eliminate the problem necessarily, but takes you out of failsafe.

The seller was willing to take it back, but since I was already home I wanted to take it to a shop before I brought it back so as not to damage it anymore than it may be. I ended up deciding to keep it and although the tranny has been a problem, I was told that the rest of the car was in great shape. So the shop I took it to said the OBD codes read Transmission Gear Monitoring and Turbine Speed Sensor. So they recommended I replace the sensor and do a tranny service. So they did the sensor and thankfully the seller paid for the diagnoses, transmission speed sensor replacement, filter and pan gasket replacement and fluid because I later found out that it may not have been necessary.

The shop I took it to specialized in Mercedes more so than BMW and my new, excellent shop told me that they probably read the code and duped me into replacing the sensor. The car went into failsafe again within a month. At the same time saying that if the fluid came out black(which it did) the tranny was not in good shape and after replacing the fluid, if it doesn't die within 3000 miles it will be ok. The new shop said bad idea to do the service because as mentioned above, when replacing old fluid with new you may cause some debris to break loose with the fluid being so good and actually encourage the tranny to fail. Guess the 1st shop was right in a sense and either knew they were trying to break my tranny or did not understand that what they recommended was not a good idea. In addition, after much diagnoses of continued problems with the tranny at my new shop they went in to check the condition of the fluid and noticed it was a pint short of fluid from that service which they said was pretty big. Seems the right amount of fluid is quite critical to their function according to my guys.

So after abandoning the previous guys and switching to my new shop(Bavarian Tuning in Santa Rosa, CA), I decided to go ahead and start doing some Dinan upgrades. Done pretty much everything except intake manifold and supercharger. Once I did the upgrades I again was having problems with my tranny. Weird stuff. When I would accelerate on to the freeway in manual mode the tranny would hang up in 3rd going to 4th. Rather than shift up to 4th and thus reducing the rpms it would actually hang in 3rd and rev up and once I took my foot off the accelerator would slam into 4th violently. So we tried to figure out what it was. The guys were convinced it was a software problem and not the tranny even with the previous history. They gave some reasons. According to them these trannys are somewhat intelligent and learn your driving style so that if the previous owner was say an old lady and you are much more aggressive, it would take some time for the computer to readjust to your driving style. May be more bull****, but I trust these guys. SO eventually after having more problems they brought Dinan and BMW into the mix.

They decided to offload the Dinan software and the original BMW software since there was an update to the BMW software. So they reloaded the updated software and had me drive it around for a few days. That's also when they noticed the low fluid and topped that off. Had no problems for a couple of days so we then loaded the Dinan software back on. The car drive the best it ever has for the first few days. No real problems. Then one day the problems came back again slowly.

Now before you start accusing these guys of duping me also I should tell you that besides the normal charges of doing the Dinan parts and software installation, all the diagnostic work and calls to Dinan and BMW were done for free. I have noticed two things about when this failsafe happens. Failsafe always happens on an incline and the car either acts up or goes into failsafe always after the car and transmission is warmed up and been driven for a while. So after all that......the conclusion is that it is the tranny itself and it needs to be fixed....LOLOLOL. Sucks doesn't it???? Being a ZF tranny they said there are only 6 shops in the US approved to rebuild these trannys and luckily one is in South San Francisco. I believe the quote is around $3700 versus a new one for $6000+. I'm told that the rebuild is excellent and no need for a new one. So I plan to do it relatively soon. I can drive the car fine, but get scared around the hills and spirited driving. It will eventually die on me so I might as well get it done and enjoy all the Dinan upgrades instead of fear that my tranny is going to explode on me.

Hope this was helpful. Sorry I didn't have a better outcome for you guys, but it seems that these trannys are pretty notorious for dying around 90K and mine was at 82K when I bought it and is now at 91K.

Last edited by M.Wong; 08-29-2009 at 12:18 PM. Reason: Just added some paragraph spacing
Reply With Quote