RG Colorado fuel economy - gauges/meters vs Actual

toadnode
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RG Colorado fuel economy - gauges/meters vs Actual

Unread post by toadnode » December 9th, 2014, 7:14 am

Hi guys, some recent experiences with my RG...

1. Fuel gauge seems inconsistent, from one short trip to the next it can go up, down and back up again. No steep roads or driveways, just normal flat ground.

2. Fuel meter reads less than actual. I reset the fuel usage every fill and find it's consistently less than what I'm putting in at the pump. Eg. last fill said 64l used and I filled with 69l at the pump. Now either there's a conspiracy against all servos brewing here or there's some kind of sensor malfunction. If this meter is calculated by the ECU's expected injection rate, would mean the engine is delivering too much fuel? Co-incidently, I've also noticed a drop in economy after fitting my 2" lift, sounds crazy right? The new leaf springs are a little heavier but I didn't think it was that much more.

3. Curious to know other peoples economy figures. I purchased my RG with 8000km's and it was achieving "8.6l/100", but that's not accurate due to factory tire size. After fitting 265/75/16 Hankooks (speedo reads 1% slower now) it dropped to around 8.9l/100. Currently, it's varying between 9.5l/100 and 10.5/100

4. I wonder if we could get a specific RG section on this forum?
Holden Colorado RG 2013(Duramax I) with Fulcrum 2" lift. (King/EFS springs and Bilstein Shocks)

Dmaxqld
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Re: RG Colorado fuel economy - gauges/meters vs Actual

Unread post by Dmaxqld » December 9th, 2014, 7:44 am

Mate, tyre size and pressure will effect fuel economy readings. If you want something more accurate, get a Scanguage II

Peter Aawen
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Re: RG Colorado fuel economy - gauges/meters vs Actual

Unread post by Peter Aawen » December 9th, 2014, 8:49 am

Lift will also increase the frontal area the vehicle presents as you drive, so the energy needed to push a bigger area thru the air will generally be more.... It's not only the weight of bar work & roof racks that adds to fuel use, it's also the 'dirty air' caused by having those things hanging off the relatively clean vehicle panels, & the added turbulence behind & under the vehicle due to the extra height. And fitting larger dia tyres without correcting your speedo/odometer will also mean that your 'distance travelled' will be less than it was (& it was probably OVER indicated on the original tyres anyway!!) plus you'll likely be pushing the vehicle thru the air faster at any given indicated speed than you were previously, both of which make your fuel economy look as tho it's taken more of a hit!!

Just like your speedo/odometer, the rest of the instrumentation/meters ect are also going to be assuming everything is standard on the vehicle, so bigger tyres meaning fewer revs per km travelled & a slower indicated speed (so that you tend to be driving faster than you were, even if you still drive at the same indicated speed) & that all impacts on the calculations the on board computers make - & with the possibility of sooo many variables making a difference, the computers in most modern vehicles are only ever designed to give a 'within the ball park' reading on things like 'fuel/distance remaining' or even the amount of fuel left in the tank!!

Besides, the manufacturer REALLY doesn't want you to run the tank empty while the vehicle is still under warranty, that could damage the fuel/injector pump & system in a fairly expensive way, so it's best to always take the computer calculated fuel readings with a grain of salt & do your own calculations with 'corrected for accuracy' distance travelled readings & the number of litres used fm the bowser (they are meant to be checked regularly by the weights & measures inspectors...) And keeping a log book that you have clearly maintained accurately to record ALL the costs/services etc associated with your vehicle can be handy for many things besides keeping an eye on your fuel consumption; it might even provide some evidence if you ever need to go to court with the manufacturer OR with a fuel outlet! ;)
An Ex-Service person is someone who thought enough about their country & how great it is, how lucky we are to live here, to write a blank cheque made out to 'The People and Commonwealth of Australia' for the value of 'Up to & including my Life!'

toadnode
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Posts: 15
Joined: November 10th, 2014, 11:24 am

Re: RG Colorado fuel economy - gauges/meters vs Actual

Unread post by toadnode » December 9th, 2014, 10:00 am

Thanks for your replys...

Hard to believe how much difference the lift made.... When I lifted my d22 Navara (same amount of lift) there was virtually no change in economy but i suppose the cabin does sit higher in the Colorado... it's also much wider too.

In general, I'm finding the Colorado economy to be extremely variable(after mods), must be the higher boost levels it runs than my former ute.

But you're right Peter, the original tyre size presents a speedo reading 4-5% faster than actual so the economy displayed appears better than actual. The current tyres have made it <1% slower which is almost negligible. Would you believe the analogue gauge also differs to the digital??

I do take distance to empty and the fuel tank readings with a grain of salt... but with regard to the fuel usage gauge, you would expect when the ECU meters (or calculates) 1 litre that it should be pretty close to being 1 litre. Modern engines operate within such fine tolerances these days that the margin for error needs to be minimal or damage could occur.

I'm going to see what Holden say about it during my next service... Cheers guys!
Holden Colorado RG 2013(Duramax I) with Fulcrum 2" lift. (King/EFS springs and Bilstein Shocks)

crakrz7
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Re: RG Colorado fuel economy - gauges/meters vs Actual

Unread post by crakrz7 » December 10th, 2014, 6:07 am

My "actual" economy has always been about 0.5 lts/100km worse than what the trip computer tells me. The Lts used has always been 4-5 more than what it says on the display too.
2012 RG Colorado, 5spd Manual, 2" Lift, Genie 3" s/s exhaust, K&N filter, CAT delete, EGR delete, HPD Intercooler, HPD catch can, Crispmods ECU remap, Auber EGT & Boost guages, Road Ranger shifter.

boehamian
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Re: RG Colorado fuel economy - gauges/meters vs Actual

Unread post by boehamian » January 6th, 2018, 11:33 pm

Hi I noticed when I done a lift in my car (3 inch front and 1 inch rear), put all my mods on (about 450kg of weight) and put bigger tyres on my fuel economy didn't change too much to actual reading. However the computer told me completely different readings. I have since got the car remapped and whilst he done this the speedo was corrected. I purposely didn't calibrated it exact as different tyres and tread wear play a big part in the reading as well but it got done so the speedo reads about 2km faster when doing 100km/h (actually reads 102km/h on speedo when doing 100). I did this so other people who drive it that tend to push the speed barrier can't blame the cars speedo and to allow the difference in height from different tyres. My car tends to read pretty true now when it comes to fuel usage (about .5l out) but that could be to a few other factors as well as I do have a long range tank. Also the distance to empty being out.


I did notice from standard that the speedo was reading 5km faster than I was actually travelling. This is due to manufacturers rules when building. They are allowed a 5% error rate but it can only read faster not slower than actually doing. So they do tend to allow a bit of error. This is also because they offer many different tyre sizes with the car and keep the same tune.


I have also noticed when going up in tyre size that my economy around town was worse but on the highway it was better. A mate in the know has advised me this is because with bigger rubber it takes your car more power to get the wheels spinning but once the tyre is spinning the extra weight of the tyre actually helps keep the momentum going therefore the engine does not have use as much power to keep it rotating (if that makes sense).

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