Transmission Issues at High Speed

[NCGenesis]

2011 4.6 Genesis Sedan w/144,000 (approx)
When at speed in top gear on the highway when passing... If I step on the gas and cause the engine/trans to drop into a lower gear to accelerate to pass, all of a sudden the engine races (to around 4K) and does not recover. What does that mean?

This has happened multiple times lately and I've tried to diagnose the exact situation. Long story short, it seems like the tranny drops down into a lower gear to pass (I think maybe two gears down) and if I let up on the gas it still maintains in the same gear and at high RPM. That said, I even pulled over behind slower cars and try to let the syatem recover, but the engine stays at high RPM in the lower gear. It seems the only way to reset the situation is to pull off the road and turn the car off. Then the system resets and things seem to work as normal. But when I get up to speed again and force the situation, it will happen again. So, in order to get home when on the highway at reasonably high speed 70, 80 and 90 I just have to be gentle and don't make it drop down to a lower gear for passing.

Second, I have pushed the tranny at lower speeds around town and it works fine. It will drop down to a lower gear and recover.

Yikes, I'm worried I can't take this thing on road trips. This has happened on the last three road trips.

Your input is appreciated,
I like my beast.

 

[RSpectnewbie]

Is this in sport mode or normal mode? Sounds like it is kicking into sport mode and will not change gears until 6,000 rpm.

Maybe try switching into sport mode and use it to raise the gears, if it is happening in normal mode. Then switch back.

If it's in normal mode, something is def. funky with the tranny.

 

[Gunkk]

2011 4.6 Genesis Sedan w/144,000 (approx)
When at speed in top gear on the highway when passing... If I step on the gas and cause the engine/trans to drop into a lower gear to accelerate to pass, all of a sudden the engine races (to around 4K) and does not recover. What does that mean?

This has happened multiple times lately and I've tried to diagnose the exact situation. Long story short, it seems like the tranny drops down into a lower gear to pass (I think maybe two gears down) and if I let up on the gas it still maintains in the same gear and at high RPM. That said, I even pulled over behind slower cars and try to let the syatem recover, but the engine stays at high RPM in the lower gear. It seems the only way to reset the situation is to pull off the road and turn the car off. Then the system resets and things seem to work as normal. But when I get up to speed again and force the situation, it will happen again. So, in order to get home when on the highway at reasonably high speed 70, 80 and 90 I just have to be gentle and don't make it drop down to a lower gear for passing.

I presume there is/was no check engine light or codes. Does manumatic "M" mode still work when this happens and can you manually change gears back into 6? What if you pop the trans in Neutral then back into Drive? Any other symptoms (rough or other delayed shifts, slipping, etc.).

IIRC the 2011 4.6 has the ZF 6HP26 trans, so from this link, "If your car has over 100K, shifting issues at this mileage are likely due to a worn valve body."

But before jumping down that rabbit hole I'd recommend that you pay a couple hondos to a competent import transmission shop do a proper diagnosis (there are a lot of ZF's in BMWs).

Is this in sport mode or normal mode? Sounds like it is kicking into sport mode and will not change gears until 6,000 rpm.

Maybe try switching into sport mode and use it to raise the gears, if it is happening in normal mode. Then switch back.

If it's in normal mode, something is def. funky with the tranny.

There is no sport mode in the 1st gen 4.6.

The Mistress (my 2017 ZL1) has such a mode called "Performance Shift Mode" that will kick in and downshift automatically and hold the RPMs up in the "racing zone" if certain conditions are met (like matting the throttle or taking a sweeping turn at high G at high speed) ... but it has a 5-10 second timeout that will return the car back to normal behavior if you don't also continue to play. It's like a little puppy that jumps up and wags its tail at you and says "LETS GO PLAY!"

 

[RSpectnewbie]

I have a "sport mode" in my '13 Rspec, at least I call it sport mode. Can manually change gears but it won't shift automatically until about 6,000 rpm or above.

 

[Gunkk]

Ahh yes, sorry, I now realize that some folks call Sport Mode what I call "manu-matic," or "M" mode, which is where you move the shift lever from "D" to the side and into the +/- slot for manual shifting.

 

[RSpectnewbie]

I understand the confusion as they did come out with a sport mode in later models. I just figured it as sport mode for that year.

 

[NCGenesis]

I presume there is/was no check engine light or codes. Does manumatic "M" mode still work when this happens and can you manually change gears back into 6? What if you pop the trans in Neutral then back into Drive? Any other symptoms (rough or other delayed shifts, slipping, etc.).

IIRC the 2011 4.6 has the ZF 6HP26 trans, so from this link, "If your car has over 100K, shifting issues at this mileage are likely due to a worn valve body."

But before jumping down that rabbit hole I'd recommend that you pay a couple hondos to a competent import transmission shop do a proper diagnosis (there are a lot of ZF's in BMWs).



There is no sport mode in the 1st gen 4.6.

The Mistress (my 2017 ZL1) has such a mode called "Performance Shift Mode" that will kick in and downshift automatically and hold the RPMs up in the "racing zone" if certain conditions are met (like matting the throttle or taking a sweeping turn at high G at high speed) ... but it has a 5-10 second timeout that will return the car back to normal behavior if you don't also continue to play. It's like a little puppy that jumps up and wags its tail at you and says "LETS GO PLAY!"

Good question(s) ref manual shifting I didn't know how much to add and frankly it all happens so fast and I'm in traffic that it's hard to absorb all scenarios and get off the road. I'm thinking of taking it out again with no traffic and try to reproduce. But...
Ref Manual shifting - no it will not go back into high gear. I tried that. It does seem to go into neutral but engine stays at about 4K RPM
Ref Console lights - No Check Engine -But there was a lamp I had not seen before, ESC (red) I believe Electronic Speed Control
Ref Other Symptoms - Not anything specific. There has always been a slight "shudder" when under load from (I think) Second to Third gear.

Thanks for your help - I believe you are right in that I had better take it to a "couple of hondos" - AND the suggestion about ZF's in BMW's. I had read about that somewhere. I believe you are right about - "If your car has over 100K, shifting issues at this mileage are likely due to a worn valve body." That's what it feels like.

I'll try to update this when I get more info.
Thanks
Thanks,

 

[RSpectnewbie]

ESC is Electronic Stability Control. Likely not part of the problem though.

 

[NCGenesis]

ESC is Electronic Stability Control. Likely not part of the problem though.

Yes, thanks for the correction. Today I did look at the console indicators and see that the ESC lamp is orange (not RED) and thus not the one I saw. I hate to give incorrect information. Sorry. Yes, I agree it doesn't have anything to do with the issue.

I'm not sure where this is going but... I'm thinking of replacing the transmission with a rebuilt. I know that sounds extreme, but, this is a sealed unit and it should remain so. I've looked into a kit to drop the bottom plate with all parts and filter included. But after that is all said and done.... Perhaps I'm better off just replacing the tranny.
Thanks again.

 

[Donovan_787]

I have a 2012 R-Spec 5.0 and it has the 8-speed automatic transmission. It shifts kind of rough between 2nd and 3rd gears. I know most likely one of the electronics inside the transmission is going bad. My question is how long can this go on before my car breaks down and leave me stranded? No check engine light yet. I do have a 100,000 mile extended warranty and they will cover this.

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[NCGenesis]

I have a 2012 R-Spec 5.0 and it has the 8-speed automatic transmission. It shifts kind of rough between 2nd and 3rd gears. I know most likely one of the electronics inside the transmission is going bad. My question is how long can this go on before my car breaks down and leave me stranded? No check engine light yet. I do have a 100,000 mile extended warranty and they will cover this.

Reference the rough / "shudder" between 2nd and 3rd
Mine has always had it since I bought it at 40K. No one else seems to feel it and only happens when pressed. So, I ignore it. No worries (for now).