Riv Performance
Would you like to react to this message? Create an account in a few clicks or log in to continue.

The 8th Gen Riviera Resource
 
HomeDashboardLatest imagesSearchRiviera Questions & AnswersWrite-Ups IndexRegisterRelated LinksLog in

 

 Unexplained MPG increase

Go down 
+7
High Chaparral
stan
AA
deekster_caddy
brutusk1
gunmetalRED
Mikel
11 posters
AuthorMessage
Mikel
Enthusiast



Name : Mikel
Age : 47
Location : New Haven, CT
Joined : 2009-07-12
Post Count : 157
Merit : 2

Unexplained MPG increase Empty
PostSubject: Unexplained MPG increase   Unexplained MPG increase EmptyMon Jun 02, 2014 10:02 pm

Hello,
I've owned two '97 Rivieras and I've never gotten the high MPG numbers other people report. I typically get about 20-22, with a small increase when spring time comes. Both cars did exactly the same.

In the last few weeks my fuel economy has all of the sudden jumped 5MPG over my previous records, four fill-ups in a row. I am obviously thrilled, but rather annoyed that I can't explain it.

The engine has 160K miles, O2 sensors, plugs and wires are 40K miles old. Air filter is a few months old. Other than oil changes, nothing has been done to it in months.

 Any ideas? Thanks.
Mikel
Back to top Go down
gunmetalRED
Member
gunmetalRED


Name : Kristin
Location : Cocoa Beach, FL
Joined : 2013-01-05
Post Count : 89
Merit : 3

Unexplained MPG increase Empty
PostSubject: Re: Unexplained MPG increase   Unexplained MPG increase EmptyTue Jun 03, 2014 8:07 am

Have you had a look at the engine compartment? I noticed a significant increase suddenly with my first Riv and it turned out my supercharger belt had broken! It ran fine without it, no Check Engine light or anything, but it was sluggish without those extra 45 horses. I missed them so I fixed it. wink

'Course maybe you're finally getting the MPGs the rest of us get too! Have your driving habits changed? The warmer weather helps too. I get about 25-26 MPG on average and I have seen 30 before. (I've also seen 14 in the winter. Ouch.)
Back to top Go down
brutusk1
Member



Name : Brutusk
Location : Bothell, Washington
Joined : 2011-01-23
Post Count : 97
Merit : 13

Unexplained MPG increase Empty
PostSubject: Re: Unexplained MPG increase   Unexplained MPG increase EmptyTue Jun 03, 2014 4:08 pm

My guess is that for some reason you're getting fuel without the "normal" amount of ethanol in it.

Have you changed fueling stations or has your fueling station changed suppliers ? 10% Ethanol in gasoline causes cars to lose (what I've read) 10 - 15% mpg due to the lower energy density in the alcohol.
Back to top Go down
deekster_caddy
Master



Name : Derek
Age : 52
Location : Reading, MA
Joined : 2007-01-31
Post Count : 7717
Merit : 109

Unexplained MPG increase Empty
PostSubject: Re: Unexplained MPG increase   Unexplained MPG increase EmptyTue Jun 03, 2014 4:19 pm

brutusk1 wrote:
My guess is that for some reason you're getting fuel without the "normal" amount of ethanol in it.

Have you changed fueling stations or has your fueling station changed suppliers ? 10% Ethanol in gasoline causes cars to lose (what I've read) 10 - 15% mpg due to the lower energy density in the alcohol.

x2 - have you started using a new gas station?
Back to top Go down
AA
Administrator
AA


Name : Aaron
Age : 47
Location : C-bus, Ohio
Joined : 2007-01-13
Post Count : 18452
Merit : 252

Unexplained MPG increase Empty
PostSubject: Re: Unexplained MPG increase   Unexplained MPG increase EmptyTue Jun 03, 2014 5:35 pm

Has your driving style or route changed at all? A 5 mpg increase is pretty significant - I'd suspect the driver to be more of a factor than the car or the fuel. Another possibility is a mistake in the fuel log, or an inaccurate fuel pump meter. Rule these out just in case.

_________________
'05 GTO 6.0L • 6-spd • 95k miles • 0-60: 4.8s • 16.9 avg MPG • Nelson Ledges Lap: 1:26

'95 Celica GT 2.2L • 5-spd • 165k miles • 0-60: yes

'98 SC Riviera • 281k miles • 298 HP/370 TQ • 0-60: 5.79s • ET: 13.97 @ 99.28 • 4087 lb • 20.1 avg MPG • Nelson Ledges Lap: 1:30
3.4" pulley • AL104 plugs • 180º t-stat • FWI w/K&N • 1.9:1 rockers • OR pushrods • LS6 valve springs • SLP headers • ZZP fuel rails
KYB GR2 struts • MaxAir shocks • Addco sway bars • UMI bushings • GM STB • Enkei 18" EV5s w/ Dunlop DZ101s • F-body calipers
EBC bluestuff/Hawk HP plus • SS lines • Brembo slotted discs • DHP tuned • Aeroforce • Hidden Hitch

^^^ SOLD ^^^ frown

'70 Ninety-Eight Holiday Coupe 455cid • 116k miles
^^^ SOLD ^^^ frown
Back to top Go down
http://www.cardomain.com/ride/657082/4
stan
Expert



Joined : 2007-07-01
Post Count : 2558
Merit : 12

Unexplained MPG increase Empty
PostSubject: Re: Unexplained MPG increase   Unexplained MPG increase EmptyTue Jun 03, 2014 5:53 pm

use a Tornado?
Back to top Go down
High Chaparral
Member
High Chaparral


Name : Chris
Age : 61
Location : Springfield, Illinois
Joined : 2014-05-04
Post Count : 75
Merit : 1

Unexplained MPG increase Empty
PostSubject: Re: Unexplained MPG increase   Unexplained MPG increase EmptyTue Jun 03, 2014 8:10 pm

Wish there were more non-ethanol stations around my neck of the woods. Seem to be increasingly rare. Found one (internet) that is 20 miles away. Next time I'm traveling that way will have to try a tankful. Pretty sure it has been quite awhile since any of my cars enjoyed the good stuff ............
Back to top Go down
Rivillac
Enthusiast
Rivillac


Name : Kevin
Location : NC
Joined : 2011-06-06
Post Count : 102
Merit : 13

Unexplained MPG increase Empty
PostSubject: Re: Unexplained MPG increase   Unexplained MPG increase EmptyTue Jun 03, 2014 9:20 pm

High Chaparral wrote:
Wish there were more non-ethanol stations around my neck of the woods. Seem to be increasingly rare. Found one (internet) that is 20 miles away. Next time I'm traveling that way will have to try a tankful. Pretty sure it has been quite awhile since any of my cars enjoyed the good stuff ............

A new station here offers it at the same price. Trouble is, it's 87 octane.
Back to top Go down
AA
Administrator
AA


Name : Aaron
Age : 47
Location : C-bus, Ohio
Joined : 2007-01-13
Post Count : 18452
Merit : 252

Unexplained MPG increase Empty
PostSubject: Re: Unexplained MPG increase   Unexplained MPG increase EmptyWed Jun 04, 2014 3:50 pm

stan wrote:
use a Tornado?

 ___________________laughat

_________________
'05 GTO 6.0L • 6-spd • 95k miles • 0-60: 4.8s • 16.9 avg MPG • Nelson Ledges Lap: 1:26

'95 Celica GT 2.2L • 5-spd • 165k miles • 0-60: yes

'98 SC Riviera • 281k miles • 298 HP/370 TQ • 0-60: 5.79s • ET: 13.97 @ 99.28 • 4087 lb • 20.1 avg MPG • Nelson Ledges Lap: 1:30
3.4" pulley • AL104 plugs • 180º t-stat • FWI w/K&N • 1.9:1 rockers • OR pushrods • LS6 valve springs • SLP headers • ZZP fuel rails
KYB GR2 struts • MaxAir shocks • Addco sway bars • UMI bushings • GM STB • Enkei 18" EV5s w/ Dunlop DZ101s • F-body calipers
EBC bluestuff/Hawk HP plus • SS lines • Brembo slotted discs • DHP tuned • Aeroforce • Hidden Hitch

^^^ SOLD ^^^ frown

'70 Ninety-Eight Holiday Coupe 455cid • 116k miles
^^^ SOLD ^^^ frown
Back to top Go down
http://www.cardomain.com/ride/657082/4
stan
Expert



Joined : 2007-07-01
Post Count : 2558
Merit : 12

Unexplained MPG increase Empty
PostSubject: Re: Unexplained MPG increase   Unexplained MPG increase EmptyWed Jun 04, 2014 4:04 pm

I know....hahaha
Back to top Go down
IFallsRon
Fanatic



Name : R.L.
Joined : 2012-11-23
Post Count : 268
Merit : 2

Unexplained MPG increase Empty
PostSubject: Re: Unexplained MPG increase   Unexplained MPG increase EmptyThu Jun 05, 2014 6:58 am

Spring MPG increase is pretty normal for me on all vehicles likely due to warmup and different blends.
Back to top Go down
rivi95era
Enthusiast
rivi95era


Name : Marc
Age : 41
Location : Albemarle
Joined : 2014-05-18
Post Count : 110
Merit : 0

Unexplained MPG increase Empty
PostSubject: Re: Unexplained MPG increase   Unexplained MPG increase EmptyThu Jun 05, 2014 8:40 am

Hey guys this may be a little off topic but I found that lucas makes and ethanol type cleaner for the fuel system. My 97 was quivering at idle and had really poor fuel mileage. Somewhere around 15 mpg or so. Well I was hesitant at first cause nobody could tell me if it was any good but I gotta say after one bottle (not even run through the system completely) has smoothed out my idle and increased my mpg to around 22. Its green so as not to be mistaken for the regular lucas injector cleaner. We have two different gas stations in town that offer premium ethanol free fuel but thats a little too high for my blood, granted my lawn mower gets it, lol  ride
Back to top Go down
brutusk1
Member



Name : Brutusk
Location : Bothell, Washington
Joined : 2011-01-23
Post Count : 97
Merit : 13

Unexplained MPG increase Empty
PostSubject: Re: Unexplained MPG increase   Unexplained MPG increase EmptyThu Jun 05, 2014 2:30 pm

rivi95era wrote:
My 97 was quivering at idle and had really poor fuel mileage. Somewhere around 15 mpg or so. ride


That sounds like the effect of dirty injectors and that the "Ethanol Cleaner" is pretty much the same thing as injector cleaner. But it sounds like it worked.

I've got some rebuilt injectors I'm planning to install, but I may try some of that Lucas Ethanol cleaner myself to see if it improves my mpg a bit.
Back to top Go down
IFallsRon
Fanatic



Name : R.L.
Joined : 2012-11-23
Post Count : 268
Merit : 2

Unexplained MPG increase Empty
PostSubject: Re: Unexplained MPG increase   Unexplained MPG increase EmptyThu Jun 05, 2014 8:07 pm

You'll want to replace fuel filter. My guy says they're a fail center.
Back to top Go down
rivi95era
Enthusiast
rivi95era


Name : Marc
Age : 41
Location : Albemarle
Joined : 2014-05-18
Post Count : 110
Merit : 0

Unexplained MPG increase Empty
PostSubject: Re: Unexplained MPG increase   Unexplained MPG increase EmptyFri Jun 06, 2014 2:30 pm

brutusk1 wrote:

rivi95era wrote:
My 97 was quivering at idle and had really poor fuel mileage. Somewhere around 15 mpg or so. ride



That sounds like the effect of dirty injectors and that the "Ethanol Cleaner" is pretty much the same thing as injector cleaner. But it sounds like it worked.

I've got some rebuilt injectors I'm planning to install, but I may try some of that Lucas Ethanol cleaner myself to see if it improves my mpg a bit.

I think there may be a little more to it than just an injector cleaner. Ethanol leaves deposits all over the engine. From the fuel pump all the way to the catalytic converter. So I am thinking that it may even be a more potent formula. We have some commercial grade lucas here at the shop and its thicker than what you buy at the auto parts store. Even with the commercial stuff it didn't correct the problem. I could be wrong but this is my theory.
Back to top Go down
albertj
Master
albertj


Name :
Location : Finger Lakes of New York State
Joined : 2007-05-31
Post Count : 8685
Merit : 181

Unexplained MPG increase Empty
PostSubject: gas mileage   Unexplained MPG increase EmptySun Jun 08, 2014 10:26 pm

Mikel wrote:
Hello,
I've owned two '97 Rivieras and I've never gotten the high MPG numbers other people report. I typically get about 20-22, with a small increase when spring time comes. Both cars did exactly the same.

In the last few weeks my fuel economy has all of the sudden jumped 5MPG over my previous records, four fill-ups in a row. I am obviously thrilled, but rather annoyed that I can't explain it.

The engine has 160K miles, O2 sensors, plugs and wires are 40K miles old. Air filter is a few months old. Other than oil changes, nothing has been done to it in months.

 Any ideas? Thanks.
Mikel

might be switch to summer blend gas, or a gas formula change

might be the SC isn't engaged for some reason

might be that tailwind off the ocean or some of that downhill both ways action

might be CT is about to close the interstates again and your car's getting its last licks in

did you switch to synthetic oil?

Albertj
Back to top Go down
Sponsored content





Unexplained MPG increase Empty
PostSubject: Re: Unexplained MPG increase   Unexplained MPG increase Empty

Back to top Go down
 
Unexplained MPG increase
Back to top 
Page 1 of 1

Permissions in this forum:You cannot reply to topics in this forum
Riv Performance ::   Supercharged 3800 Tech :: Series II Engine & Transmission-
Jump to: