5th To 2nd Downshift?

[loanshark]

I Own A 2002 X5 Manual 30,000.00 Miles Bumper To Bumper. While Driving 70mph On Hwy Car Losses Speed And Stops. Won't Start Anymore. The Dealer Says I Downshiftet From 5th Gear To A 2nd. And I Blew The Engine. To My Knowlege Such A Thing Is Imposible On Top Of It I Am Driving Sticks For Past 10 Years. Is There Anyone Out Ther Who Can Help Me Cause Dealer Wants Me To Pay$11,000.00 For A New Engine. Please Help

[sfca-325i]

I Own A 2002 X5 Manual 30,000.00 Miles Bumper To Bumper. While Driving 70mph On Hwy Car Losses Speed And Stops. Won't Start Anymore. The Dealer Says I Downshiftet From 5th Gear To A 2nd. And I Blew The Engine. To My Knowlege Such A Thing Is Imposible On Top Of It I Am Driving Sticks For Past 10 Years. Is There Anyone Out Ther Who Can Help Me Cause Dealer Wants Me To Pay$11,000.00 For A New Engine. Please Help

I believe this is the notorious "money shift". You might want to try a search and you'll see that this occurs fairly frequently. I'll search around, but IIRC, one owner was able to get insurance to cover the cost of the repair.

BTW, the black box probably recorded the overrev on the downshift, which is what the SA uses to confirm the moneyshift.

[Nick325xiT 5spd]

Well...

I'd try speaking English first...

Then I'd try explaining exactly what happened clearly.

And finally, no shifting from 5th to 2nd is not at all impossible.

[HW]

yep, not impossible. almost did it once, saw the rpm go up to fast as i was slipping the clutch and quickly slammed down on the clutch before it redlined. usually i rev match and drop the clutch but that time i didn't. :eek: kinda lucky.

is that a new annoyance strategy? capitalizing every word in a sentence? :dunno:

[Emission]

It's usually a 3-2 shift that does it...

You hit redline in 2nd, then hit 3rd... Redline in 3rd, then (in the excitement of the moment) pull back hard into 2nd again... and drop out the clutch... the engine is at 6200 rpm... the speedo at 80+... and the engine goes.... ouch.....

It's not that hard to miss that shift, especially in a corner on the track. Happens often. Too often.

OBD download by the dealer will see the RPM at 8000... :cry:

[sfca-325i]

OBD download by the dealer will see the RPM at 8000... :cry:


Emission is right. If the OBD download shows an overrev, you are SOL.
Ask to view the OBD download.

[Emission]

Attached as a PDF is the OBD download from my X5 (automatic) the other day. It includes my speed (!), coolant temp, engine load, engine RPM.

This was a mix of city and highway driving. It is pretty easy to see which is which... and scary to see how much info is stored. You can see an RPM spike of about 5000 rpm at 50 minutes time. I was accelerating hard to pass someone. A spike of 8000 would be obvious - especially followed by a flat line.

[dkl]

Why do BMW's engines have such a low red line (with the exceptions of the Ms)? I thought DOHC engines are supposed to be able to rev much higher than that 6000RPM red line. I mean, come on...my SOHC Honda Accord's V6 have higher red line than my DOHC BMW X5? What gives?

[swchang]

The rev limiter doesn't catch it? Why not?

[HW]

Why do BMW's engines have such a low red line (with the exceptions of the Ms)? I thought DOHC engines are supposed to be able to rev much higher than that 6000RPM red line. I mean, come on...my SOHC Honda Accord's V6 have higher red line than my DOHC BMW X5? What gives?
rev limits are determined by ability/speed of the valve springs. maybe honda has lotsa patented techniques for this. honda has lotsa experience w/ sport bike technology.

[HW]

The rev limiter doesn't catch it? Why not?
on downshifts, the engine rpm goes up because the vehicle inertia and wheel spins up the engine rpm to match the vehicle speed at the gear. there is no way to prevent the engine from spinning up while the engine is connected to the wheels. the rev limiter is basically a fuel cutoff. the engine will still spin up. the only thing would be to have a hydraulic system to disengage the clutch *and* cut the gas when the rpm goes above redline. but w/ such as system, you can get smg in there at only the cost of more sensors and more programming. not sure why smg doesn't have a saved-your-@ss feature. :dunno:

[swchang]

on downshifts, the engine rpm goes up because the vehicle inertia and wheel spins up the engine rpm to match the vehicle speed at the gear. there is no way to prevent the engine from spinning up while the engine is connected to the wheels. the rev limiter is basically a fuel cutoff. the engine will still spin up. the only thing would be to have a hydraulic system to disengage the clutch *and* cut the gas when the rpm goes above redline. but w/ such as system, you can get smg in there at only the cost of more sensors and more programming. not sure why smg doesn't have a saved-your-@ss feature. :dunno:

So you can blow the engine on SMG as well?

[HW]

So you can blow the engine on SMG as well?
i think you can but not sure. i don't own one.

[philippek]

i think you can but not sure. i don't own one.

The SMG won't execute a shift that would over-rev the engine.

[kyfdx]

Attached as a PDF is the OBD download from my X5 (automatic) the other day. It includes my speed (!), coolant temp, engine load, engine RPM.

This was a mix of city and highway driving. It is pretty easy to see which is which... and scary to see how much info is stored. You can see an RPM spike of about 5000 rpm at 50 minutes time. I was accelerating hard to pass someone. A spike of 8000 would be obvious - especially followed by a flat line.


Wow!! Big Brother really is watching. I notice that is for a 2 hour time window.. Is that as far back as they can go? How much of that info is stored in there forever.. seems like you would run out of memory.

[swchang]

Attached as a PDF is the OBD download from my X5 (automatic) the other day. It includes my speed (!), coolant temp, engine load, engine RPM.

This was a mix of city and highway driving. It is pretty easy to see which is which... and scary to see how much info is stored. You can see an RPM spike of about 5000 rpm at 50 minutes time. I was accelerating hard to pass someone. A spike of 8000 would be obvious - especially followed by a flat line.

What the heck were you doing between 41 and 50 minutes? :dunno:

[Desertnate]

Wow!! Big Brother really is watching. I notice that is for a 2 hour time window.. Is that as far back as they can go? How much of that info is stored in there forever.. seems like you would run out of memory.

I was wondering the same thing.

Maybe it only stores a couple of days worth along with any events that are beyond normal limits like a money shift? :dunno:

[Emission]

What the heck were you doing between 41 and 50 minutes? :dunno:

First, the 41-50 minute period was in traffic after an accident on the freeway. You can see I was cruising 70-80... then I hit the traffic.

There was another accident at 25 minutes... notice the drop to nearly zero speed? Four cars spun out in front of me. I slowed, then got out of there when I noticed everyone was OK.

The device I used was a CarChip. It holds 300 hours of data and is available for about <$200. Pretty cool. Car Chip (http://www.davisnet.com/drive/products/carchip_products.asp)

[andy_thomas]

Why do BMW's engines have such a low red line (with the exceptions of the Ms)? I thought DOHC engines are supposed to be able to rev much higher than that 6000RPM red line. I mean, come on...my SOHC Honda Accord's V6 have higher red line than my DOHC BMW X5? What gives?
"DOHC" is nothing to do with being able to rev high. What allows you to rev high is light internals, a short crank, lightweight valve gear, small capacity, and (preferably) a relatively short piston stroke.

Some of BMW's engines have fairly long strokes. The smaller ones - the ones, if you're a USian, you don't get - rev higher.

Besides, Honda is particularly well known for building engines which like high revs (and which tend not to have a lot of torque). Why did you use Honda as a comparison?