Trans dropped to 2nd on highway, major overrev

avocet · 09-03-2024, 04:58 PM

On my X5d I was cruising on highway at maybe 75mph with a trailer with 2 motorcycles in it(maybe 3500lbs) when my trans jammed into second and my revs hit the stop past redline. Trans wouldn't shift or go into neutral. I got over to the side of the road but rpms were in the red for quite some time. I had the gear icon in dash, and it stayed on with it in 2nd until I came to a stop and shut down.
I restarted and the light was gone, and it shifted into drive normally. I crept to the nearest offramp(maybe an 1/8 mile) and as I got off the highway my engine began to tick.
I stopped and checked codes with Carly. No trans codes, but had 459b Smooth running controller cyl. 5 and 4595 smooth running controller cyl. 6 engine codes. I thought maybe it was injectors and nursed it into a nearby parking lot since there was no real safe place to remain stopped.
The ticking was consistent with rpm, and even would subside and almost go a way for a minute at a time. She was a little rough on idle and felt low on power. The parking lot I was in was a reserved lot, and the owners asked I do not park there. I had called AAA and a tow was coming, but I had to cross the lot so the delivery trucks could access the building.
When I went to restart and cross the lot, all hell broke loose. Major knock and clucking and ran like crap. Like major knock. I shut down and waited for tow to the nearest euro mech. shop. The shop owner was able to come over and tow my trailer to his lot, and I got my X5 towed there.

Long story short, it really seems like my engine to toast. Over rev to structural internal failure seems likely consider the rev counter was pegged on the high end for awhile.

Now, the question is, WTF caused this? I am at 197,000km (~130000 miles), so not a very high mileage vehicle, and have been running an xHP stg 3, no drag race mode, no launch control and no line pressure bump. Full deletes with JR2.8. Vehicle is driven fast but not crazy hard. Fluids and filters recent.

Do I put in a new engine and risk exploding it if the trans does what it did again?
Anyone with any insight on WTF happened?

Nadir Point · 09-15-2024, 09:20 PM

https://en.wikipedia.org/wiki/Diesel_engine_runaway How's ur CCV setup?

lnxguy · 09-20-2024, 12:06 PM

He's not going to get a runaway from anything coming out the CCV. Only time a runaway happens is when a turbo lets go and he'll absolutely know what's happening.

I wouldn't put a new/used engine in until you figure out what's going on with the transmission.

whyzee125 · 09-21-2024, 11:48 PM

Agreed, runaway diesels are scary but that’s not what happened here. Seems like some sort of TCU or wiring fault? Maybe check your mechatronoc sleeve and bridge adapter for leaks? I heard that can leak fluid into the TCU and cause problems but I’ve never heard of that actually happening and don’t know if it’s true.

avocet · 09-25-2024, 06:00 PM

Ya definitely not a runaway scenario. New(used) engine and trans installed with donor TCU in trans. TCU was revirginized and I am going to run this for awhile and let it adapt and see how it all settles in. I will wait for reflashing trans if ever.

But, I got a decent powertrain with decent(less) mileage and it all seems pretty happy so far after one day of driving it.

Unfortunate, and I am certainly hoping it is a one off failure. I have not been able to find any one out there that has had a similar failure.

Fingers crossed!

09-03-2024, 04:58 PM	#1
avocet Major 273 Rep 1,166 Posts Drives: 2007 328i 2011 X5d Join Date: Sep 2010 Location: Vancouver bc iTrader: (0)	Trans dropped to 2nd on highway, major overrev On my X5d I was cruising on highway at maybe 75mph with a trailer with 2 motorcycles in it(maybe 3500lbs) when my trans jammed into second and my revs hit the stop past redline. Trans wouldn't shift or go into neutral. I got over to the side of the road but rpms were in the red for quite some time. I had the gear icon in dash, and it stayed on with it in 2nd until I came to a stop and shut down. I restarted and the light was gone, and it shifted into drive normally. I crept to the nearest offramp(maybe an 1/8 mile) and as I got off the highway my engine began to tick. I stopped and checked codes with Carly. No trans codes, but had 459b Smooth running controller cyl. 5 and 4595 smooth running controller cyl. 6 engine codes. I thought maybe it was injectors and nursed it into a nearby parking lot since there was no real safe place to remain stopped. The ticking was consistent with rpm, and even would subside and almost go a way for a minute at a time. She was a little rough on idle and felt low on power. The parking lot I was in was a reserved lot, and the owners asked I do not park there. I had called AAA and a tow was coming, but I had to cross the lot so the delivery trucks could access the building. When I went to restart and cross the lot, all hell broke loose. Major knock and clucking and ran like crap. Like major knock. I shut down and waited for tow to the nearest euro mech. shop. The shop owner was able to come over and tow my trailer to his lot, and I got my X5 towed there. Long story short, it really seems like my engine to toast. Over rev to structural internal failure seems likely consider the rev counter was pegged on the high end for awhile. Now, the question is, WTF caused this? I am at 197,000km (~130000 miles), so not a very high mileage vehicle, and have been running an xHP stg 3, no drag race mode, no launch control and no line pressure bump. Full deletes with JR2.8. Vehicle is driven fast but not crazy hard. Fluids and filters recent. Do I put in a new engine and risk exploding it if the trans does what it did again? Anyone with any insight on WTF happened?
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09-15-2024, 09:20 PM	#2
Nadir Point Lieutenant 104 Rep 589 Posts Drives: Diesel Join Date: Dec 2015 Location: CO iTrader: (0)	https://en.wikipedia.org/wiki/Diesel_engine_runaway How's ur CCV setup?
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09-20-2024, 12:06 PM	#3
lnxguy Colonel 531 Rep 2,049 Posts Drives: 2018 540i xDrive. Join Date: Jun 2016 Location: Barrie iTrader: (1)	He's not going to get a runaway from anything coming out the CCV. Only time a runaway happens is when a turbo lets go and he'll absolutely know what's happening. I wouldn't put a new/used engine in until you figure out what's going on with the transmission. __________________ '09 335D '18 540i xDrive
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09-21-2024, 11:48 PM	#4
whyzee125 Brigadier General 1991 Rep 4,013 Posts Drives: Dinan stage 2 335i Join Date: Jul 2014 Location: Chattanooga Tn iTrader: (0)	Agreed, runaway diesels are scary but that’s not what happened here. Seems like some sort of TCU or wiring fault? Maybe check your mechatronoc sleeve and bridge adapter for leaks? I heard that can leak fluid into the TCU and cause problems but I’ve never heard of that actually happening and don’t know if it’s true.
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09-25-2024, 06:00 PM	#5
avocet Major 273 Rep 1,166 Posts Drives: 2007 328i 2011 X5d Join Date: Sep 2010 Location: Vancouver bc iTrader: (0)	Ya definitely not a runaway scenario. New(used) engine and trans installed with donor TCU in trans. TCU was revirginized and I am going to run this for awhile and let it adapt and see how it all settles in. I will wait for reflashing trans if ever. But, I got a decent powertrain with decent(less) mileage and it all seems pretty happy so far after one day of driving it. Unfortunate, and I am certainly hoping it is a one off failure. I have not been able to find any one out there that has had a similar failure. Fingers crossed!
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