Does engine breaking cause damage
06-27-2008 | 05:58 AM
#11
Contributors
Joined: Jul 2005
Posts: 445
Likes: 0
From: Salem, NH USA
06-27-2008 | 06:09 AM
#12
Contributors
Joined: Apr 2007
Posts: 5,851
Likes: 3
From: Kajaani, Finland
My Ride: Bmw 530d 2004
Originally Posted by bdkinnh' post='611214' date='Jun 27 2008, 04:58 PM
How exactly? Pushing in the clutch and using the brakes brings the engine to idle. Engine braking ups the RPM. Higher RPM = more fuel used.
edit: There's lots of incosistent information about this issue in the web and there can be differencies in fuel injection systems between different manufacturers.
Look at this: Ecodrive.org. Especially "Decelerate smoothly" chapter.
06-27-2008 | 06:45 AM
#13
Contributors
Joined: Dec 2007
Posts: 8,998
Likes: 1
From: St. Louis Burbs, USA
My Ride: 2007 530i. Purchased 6/28/07. Titanium Silver Metallic, Black Dakota Leather, Dark Poplar Trim, Steptronic, Premium Package, Cold Weather Package, Bluetooth, Adaptive Control Xenons. 10/30/07 Added OEM 124s with 245/40/18 & 275/35/18 Michelin Pilot Sport A/S tires. Installed red Cal Covers� from BavAuto. 11/21/07 Added OEM all-weather floor mats (for winter, carpet in summer) and coat rack. 6/26/08 installed M5-style rear spoiler. 6/30/08 put on red reflectors. 8/22/08 Euro turn signal stickers applied. 3/20/09 Installed Shadowline Trim. 3/27/09 Added Matte Black Kidney Grilles from Trinity. 4/03/09 Installed Bimmian Shadow Matte Black 530i Badges. 4/04/09 Installed LED license plate lights from Trinity. 5/01/09 Installed Brabus Interior LED Kit and White Angel Eyes. 5/02/09 Put in Brabus 6K Fogs. 5/14/09 Removed charcoal filter. 5/15/09 Installed light smoke LED side marker lamps from Trinity. 5/21/09 Sprint Booster. 6/12/09 Painted exhaust tips flat black. 6/13/09 Pulled red Cal Covers and painted calipers low gloss black. 6/27/09 RPI Ram Air Scoop from Trinity. 8/15/09 Installed Brabus's silver invisibulbs front and rear. 9/24/09 Installed R-Dash license plate LEDs from Brabaus (John).
Gear changes are designed to increase speed, while brakes are designed to slow the car. Downward gear changes should only be used to match the cars's speed/revs for the purposes of acceleration, generally following braking. There are exceptions to this, such as extended steep mountain descent situations where your brakes will overheat, etc., but in general you should slow the car only with the brakes.
06-27-2008 | 08:53 AM
#15
Contributors
Joined: Jul 2005
Posts: 445
Likes: 0
From: Salem, NH USA
Originally Posted by Anzafin' post='611218' date='Jun 27 2008, 10:09 AM
Nope. Modern fuel injection systems are designed to cut fuel injection when engine braking is noticed.
edit: There's lots of incosistent information about this issue in the web and there can be differencies in fuel injection systems between different manufacturers.
edit: There's lots of incosistent information about this issue in the web and there can be differencies in fuel injection systems between different manufacturers.
06-27-2008 | 09:00 AM
#16
Contributors
Joined: Apr 2007
Posts: 5,851
Likes: 3
From: Kajaani, Finland
My Ride: Bmw 530d 2004
Originally Posted by bdkinnh' post='611340' date='Jun 27 2008, 07:53 PM
If you're staying in the same gear, perhaps. If you're downshifting, no way. The RPMs will go up; if these modern fuel injection systems have figured out a way to up the RPMs and reduce fuel use at the same time, I'd love to hear about it.
.
06-27-2008 | 11:49 AM
#17
Members
Joined: May 2007
Posts: 54
Likes: 0
From: Atlanta Georgia USA
My Ride: 2008 535i ALS, Nav, Cold Weather package, Premium package, Logic 7
On my 535i (auto trans) with the cruse control engaged - when I go down a hill and the speed starts to pick up the car will automatically down shift. I know this because the rpms increase. It only appears to shift out of the 6th gear. If the hill is steep enough then the car will apply the brakes to keep the speed at the cruse control set point.
On one occasion going down a long steep hill I manually downshifted again (to the 4th gear) to reduce the amount of time the brakes were being applied.
On one occasion going down a long steep hill I manually downshifted again (to the 4th gear) to reduce the amount of time the brakes were being applied.
06-27-2008 | 03:20 PM
#18
Senior Members
Joined: Mar 2007
Posts: 423
Likes: 0
From: Manchester, UK
My Ride: E60 525d M-Sport Saloon M57N2 3.0d LCI
EXTERIOR: Jet Black, ///M-Aerodynamic Bodystyling, ///M-Rear Spoiler, De-badged, Gradual Tint Windscreen, ///M-Double Spoke 172M 19" Alloy Wheels (with non-run flats & space saver spare wheel) & ///M-Sports Suspension;
INTERIOR: ///M-Steering Wheel, Black Dakota Leather Heated Sports Seats with Electric Lumbar Supports, Brushed Aluminium Interior Trim & Anthracite Headlining.
Originally Posted by CWS530' post='611245' date='Jun 27 2008, 03:45 PM
Gear changes are designed to increase speed, while brakes are designed to slow the car. Downward gear changes should only be used to match the cars's speed/revs for the purposes of acceleration, generally following braking. There are exceptions to this, such as extended steep mountain descent situations where your brakes will overheat, etc., but in general you should slow the car only with the brakes.
06-27-2008 | 03:25 PM
#19
Senior Members
Joined: Mar 2007
Posts: 423
Likes: 0
From: Manchester, UK
My Ride: E60 525d M-Sport Saloon M57N2 3.0d LCI
EXTERIOR: Jet Black, ///M-Aerodynamic Bodystyling, ///M-Rear Spoiler, De-badged, Gradual Tint Windscreen, ///M-Double Spoke 172M 19" Alloy Wheels (with non-run flats & space saver spare wheel) & ///M-Sports Suspension;
INTERIOR: ///M-Steering Wheel, Black Dakota Leather Heated Sports Seats with Electric Lumbar Supports, Brushed Aluminium Interior Trim & Anthracite Headlining.
Originally Posted by Anzafin' post='611350' date='Jun 27 2008, 06:00 PM
When engine braking, the wheels/driveline are spinning the engine (RPMs go up), and as a result, the ECU does not see a demand for fuel. Now you've heard .
.