High or low gear? - Fuelly Forums

Click here to see important news regarding the aCar App

Reply
 
Thread Tools Display Modes
 
Old 04-28-2018, 04:01 AM   #1
Registered Member
 
Join Date: Jun 2017
Posts: 514
Country: United Kingdom
Location: Kirkcaldy
High or low gear?

I have found that when climbing a hill, on my 1.2 litre 4 pot Jazz, I get much better mpg (as indicated by my ScanGauge E) by sticking to 5th gear, low rpm and throttle well open. If I select a lower gear, higher revs and a light throttle, the mpg figure drops (in 3rd it can go down to 50% of 5th gear figure).
And I am talking about lugging along at 1500 - 2000 rpm here. Obviously the throttle being almost full open is making the difference. No pumping restriction.
I am also trying to get out of the habit of coasting, for an upcoming driver assessment (I will be 70 in July and as I have to re-apply for my licence I am having my driving voluntarily checked at the same time). Since stopping coasting I have noticed a drop in mpg, even though I aim to make as much use of DFCO as possible. It is not a great deal, only about 5%, but once the assessment is over I will go back to engine on coasting.
__________________

__________________
2006 Honda Jazz 1.2i-DSi S Vivid Blue Pearl
JockoT is offline   Reply With Quote
Old 04-28-2018, 07:46 AM   #2
Registered Member
 
Join Date: Nov 2007
Posts: 1,575
Country: United States
Location: north east PA
An old Gassaver poster did the same; staying in high gear for hills.
__________________

trollbait is offline   Reply With Quote
Old 04-28-2018, 08:34 AM   #3
LDB
Registered Member
 
Join Date: Jun 2013
Location: Houston suburb
Posts: 396
Country: United States
Location: Friendswood, (Houston suburb)
What effect does that have on the engine, lugging and pulling a heavy load vs. drop one gear and not lug the engine under heavy load? Is the mpg gain worth the extra cost in engine stress? I can see maybe not dropping to 3rd and spinning pretty fast but wonder about 4th vs 5th and the strain on the engine that doesn't immediately appear in a mpg number.
__________________
2018 Accord Hybrid Champagne/Ivory

LDB is offline   Reply With Quote
Old 04-28-2018, 09:10 AM   #4
Registered Member
 
Join Date: Jun 2017
Posts: 514
Country: United Kingdom
Location: Kirkcaldy
Not really worried about the engine. I am not causing it to struggle. If it starts to struggle I change down. It is a 12 year old car with 103,000 miles on it. I am sure it has had to suffer worse than that in its time!
__________________
2006 Honda Jazz 1.2i-DSi S Vivid Blue Pearl
JockoT is offline   Reply With Quote
Old 04-28-2018, 09:12 AM   #5
Registered Member
 
Join Date: Nov 2007
Posts: 1,575
Country: United States
Location: north east PA
I think it depends upon how much load you are actually putting on the engine. Calling for a fraction of the power the engine can produce at that rpm is less stress than all the power it can.

Then rpms over 1500 aren't exactly low. That was around where the Sonic's automatic tried to keep it.
trollbait is offline   Reply With Quote
Old 04-28-2018, 09:15 AM   #6
Registered Member
 
Join Date: Jun 2017
Posts: 514
Country: United Kingdom
Location: Kirkcaldy
Just found this, which is basically what I am doing. Method 1 first section.
https://www.wikihow.com/Drive-Uphill
__________________
2006 Honda Jazz 1.2i-DSi S Vivid Blue Pearl
JockoT is offline   Reply With Quote
Old 04-30-2018, 09:55 AM   #7
Registered Member
 
Join Date: Nov 2007
Posts: 1,575
Country: United States
Location: north east PA
Nice find. That is how I approach a hill with an automatic.

The wiki needs updating on some bits, but those mostly can be summed up as "read the owner's manual". Most cars have hill start assist now, but how they work varies between manufacturers. On a Chevy, it works once you come to a stop on the incline, but Toyotas require the brake pedal to be depressed further for it to engage.

Then not every automatic low gear selection works to lock out the higher gears. Some can still access those high gears, but the shift points for every gear has been changed.
trollbait is offline   Reply With Quote
Old 04-30-2018, 01:18 PM   #8
Registered Member
 
Join Date: Jun 2017
Posts: 514
Country: United Kingdom
Location: Kirkcaldy
I have never driven a car with all these fancy gadgets (at least not that I was aware of). I was taught to do a handbrake hill start and have never had a problem with it. This is the first manual transmission car I have owned with more than 4 gears. For about the first 10 years of my driving I only drove 3 speed transmissions. I found 4 a bit of a handful to begin with!
__________________
2006 Honda Jazz 1.2i-DSi S Vivid Blue Pearl
JockoT is offline   Reply With Quote
Old 04-30-2018, 11:59 PM   #9
Registered Member
 
Join Date: Aug 2009
Posts: 2,685
Country: United Kingdom
Location: Mid Wales
My mum has an automatic, drives me insane, when she ascends this large hill, it switches to third and screams all the way up and refuses to change up, even when lifting off the throttle. It's very frustrating and annoying. She has a new car on order, another auto, but luckily it has the the paddles so at least when I'm driving it, I have control and I decide what gear to be in and when to be in it.

In my car, it's high power to weight ratio means I ascend every hill in 6th, and gently feather the throttle to maintain speed, but not overuse fuel.
Draigflag is offline   Reply With Quote
Old 05-01-2018, 12:28 AM   #10
Registered Member
 
Join Date: Jun 2017
Posts: 514
Country: United Kingdom
Location: Kirkcaldy
I take it your mum has a CVT gearbox? I tried one out but found it too frenetic for my taste. I drove automatics for 25 years prior to this Jazz, but the traditional, hydraulic type.
If you ascended a hill with cruise control on it would often change down, but without cruise control all you had to do is ease back on the throttle and it would stay in the highest ratio.
Even with my low powered Jazz, most hills I can ascend in 5th (Top) and ease back as I crest the summit.
__________________

__________________
2006 Honda Jazz 1.2i-DSi S Vivid Blue Pearl
JockoT is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Fuelly Android Apps
Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 01:42 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.