CleanIsFast Journal: BMW X5 4.6iS

[crystalworks]

Originally Posted by CleanIsFast

I have already replaced the transmission fluid and filter. About 2,000 miles ago. Symptoms is the same before and after.

Possibly a bad wire harness transmitting bad temp readings?

If you did not replace the mechatronic harness sealing sleeve it would be a good idea. The shop I was at would not do trans service without also replacing that seal.

[X53Jay4.8is]

Originally Posted by crystalworks

If you did not replace the mechatronic harness sealing sleeve it would be a good idea. The shop I was at would not do trans service without also replacing that seal.

Original Poster I believe does not have the 6-speed Auto Trans so no Mechatronic with sealing sleeve. He has the 4.6is with 5-speed trans

[CleanIsFast]

Jay is correct, 4.6iS so only a 5-speed here (5HP24)

After reading this, I am more inclined to say it's a temperature thing with these transmissions: https://xoutpost.com/bmw-sav-forums/...-solution.html

Even after TC replacement, he was still having the 2-1 downshift. So, I've seen aftermarket coolers help along with different thermostats.

[bcredliner]

Originally Posted by CleanIsFast

I have already replaced the transmission fluid and filter. About 2,000 miles ago. Symptoms is the same before and after.

Possibly a bad wire harness transmitting bad temp readings?

I am certainly not a transmission expert but from my experience the symptoms don't really match up with bad temp sensor. However, I would eliminate the potential of an overheating problem by reading the pan temperature with an infrared heat reading tool after a few miles of driving.

There is wiring harness that goes into the transmission pan that does have a temp sensor on it that sometimes fail. It a fairly easy DIY but I wouldn't go there without more troubleshooting. And, there are other reasons the transmission could be overheating, if in fact, you verify that is the case.

As an aside, how did you verify the transmission is filled to the proper level?

[CleanIsFast]

Originally Posted by bcredliner

I am certainly not a transmission expert but from my experience the symptoms don't really match up with bad temp sensor. However, I would eliminate the potential of an overheating problem by reading the pan temperature with an infrared heat reading tool after a few miles of driving.

There is wiring harness that goes into the transmission pan that does have a temp sensor on it that sometimes fail. It a fairly easy DIY but I wouldn't go there without more troubleshooting. And, there are other reasons the transmission could be overheating, if in fact, you verify that is the case.

As an aside, how did you verify the transmission is filled to the proper level?

I mean I have to have some sort of trust in my local mechanic that he knows what he is doing. It took about 7-8L when it was refilled. Properly filled going through all the gears, driving, back on the lift and fillled again until overflow.

[bcredliner]

Originally Posted by CleanIsFast

I mean I have to have some sort of trust in my local mechanic that he knows what he is doing. It took about 7-8L when it was refilled. Properly filled going through all the gears, driving, back on the lift and fillled again until overflow.

Not challenging, thought is a good idea to make sure since low fluid can cause your symptoms. You mention driving in the process. The second fill should be done at or very close to 140 degrees.

[wpoll]

Originally Posted by bcredliner

Not challenging, thought is a good idea to make sure since low fluid can cause your symptoms. You mention driving in the process. The second fill should be done at or very close to 140 degrees.

+1 - if the second fill to obtain the correct level was after driving (even a short distance) then the fluid is likely to be too hot for a correct level check and the level will be slightly low.

[CleanIsFast]

Originally Posted by bcredliner

Not challenging, thought is a good idea to make sure since low fluid can cause your symptoms. You mention driving in the process. The second fill should be done at or very close to 140 degrees.

Originally Posted by wpoll

+1 - if the second fill to obtain the correct level was after driving (even a short distance) then the fluid is likely to be too hot for a correct level check and the level will be slightly low.

Okay, I ordered another liter of ZF AT Fluid and will top off (if necessary). I still don't think it'll aleviate the issue but cost of 1 liter is worth a try.

Also ordered a cabin filter to replace the old one. Just in time for pollen season.

[CleanIsFast]

Cabin filter replaced (amazing how big it is). Still waiting for a day to get underneath the beast and possibly top off the transmission fluid (if needed). I also ordered a blackstone oil lab kit for next oil service. Possibly get a quick oil analysis to see the relative health of the motor without dropping the oil pan.

Vehicle still pulls like a freight train. No real chain slap or "marble in can" noises at all. I have a startup squeal from the starter so that'll have to be replaced sometime soon. A bit embarassing having the startup squeak in public...Other times it starts up perfect - super quiet.

[CleanIsFast]

Okay these quotes are from the 4.6iS Registry thread. I didn't want to muddy up that thread about transmission woes.

"

Originally Posted by dannyzabolotny

Before you drop the oil pan and replace the heat sensor, plug in some kind of real time scan tool that can read the transmission temperature. If the sensor is on the fritz then it'll show some crazy number. My 540it had that issue in the winter, it would show the transmission temp as 130ºC after sitting all night! Now if the transmission temperature sensor is working and showing a correct number (as in, it starts cool when you start the car and rises as you drive) then that's not the issue. If the sensor starts showing a really high temperature when the car is at operating temperature, then you might have other issues like a bad transmission thermostat or a bad transmission heat exchanger. That's a very common issue with the early L322 Range Rovers (same M62tu and 5HP24).

Originally Posted by bcredliner

Symptoms are somewhat random shifts and sometimes will downshift from 5th to 4th or 3rd when you are cruising. I used infrared temp reader for verification and read OBC for error codes and saw I had the associated code. I don't think the 2-1 is a symptom of temp sensor and even if it is that is also a symptom of other issues.

Originally Posted by jopecasa

Have you tried clearing transmission adaptations via INPA?......might help.

"

Basically just need to get some software and look at the readings. But here is another wrench I'll throw in that I noticed today and it was a bit shocking.

So it was about 95*F yesterday so obviously I had the A/C on in the vehicle. I noticed on the way to work that the 2-1 downshift lurch wasn't there anymore. Completely gone, baffled...Then I thought to myself "well maybe the vehicle didn't get up to normal operating temperature 100%" - which could be possible since it's only about a 12 mile drive to work.

Figured I'd see if the same thing occured on the way back home that evening. Same scenario, blazing outside, A/C on. This time stuck in DC metro traffic (car fire on the highway), two lanes were closed off so it took a lot longer to get home. Vehicle was definitely up to normal operating temperature. Again, the 2-1 downshift lurch wasn't there...So, once I got off the highway I turned off the A/C and continued to drive as normal. Lo and behold...it came back!

My assumption, the A/C unit when on keeps the rev's slightly higher which 'somewhat' cured the transmission 2-1 downshift??? I highly doubt the A/C is cooling the transmission or transmission thermostat. This brings me back to - when the vehicle is in 'sport mode' the 2-1 downshift lurch is not there at all either. My assumption is that 'sport mode' keeps the rev's slightly higher as well. But the 2-1 downshift isn't present until 'normal operating temp' as well, any temp before and it's not there at all.

Maybe my vehicle is idling too low? Maybe I can program the rev's to be slightly higher?