Fuel MPG went from Great to BAD

[FlyboyTR]

We have an 04 Vue with V-6 Auto. Approximately 50,000 miles. It has always gotten between 26 -31 MPG (city, highway, loaded, A/C...) I've always ran my tire pressure 5 psi high. In the past 2 months the MPG has dropped into the 17 MPG range. No other changes noted. I am showing no codes, brakes do not appear to be dragging (tires roll freely) and there are no strange parts dragging under the vehicle. Any thoughts would be appreciated. Thanks!

FlyboyTR :)

[sspeer]

Is the performance any different?

[FlyboyTR]

Sorry to have been so long in acknowledging your question... I've been "over there." ...now back home safe and sound!

No, the performance did not change. No dark smoke or nothing that would indicate the engine is running rich. The Vue has been driven very little during the past 9 months. I just returned from a weekend trip in it. It is still getting between 17 & 19 MPG. This is still a long ways from the, almost 31 MPG's it was getting before the sudden change. The change occurred within one tank of gas!

Again, any help would be sincerely appreciated. Thanks!

Flyboy... God Bless America... :)

[fdryer]

Welcome back from being "over there"! Other than a clogged air filter maybe its a bad tank of gas or the ethanol blend required for winter use that lowers fuel mileage.:usa:

[jdmessner]

I'll bet there's nothing wrong with your Vue.

Last year, the EPA banned the used of MTBE as an oxygenate in fuel. It was used to reduce the vehicle emissions, but remained in tact after the combustion process and was being washed into water supplies every time it rained. MTBE is a known carcinogen.

The EPA mandated a percentage blend of ethanol into every grade of fuel sold in the US as a replacement for MTBE.

10% Ethanol blended fuel will reduce your overall fuel economy.

Compounded with the ethanol is the use of 'winter blend' gasoline. It is reformulated during the winter months to improve the combustability and improve the cold start.

The reformulated fuel burns more easily, and does not deliver the same economy that you would see from 'summer blend' fuel.

It is likely that your economy will recover come spring, but the new ethanol blends will not give you the same economy that you are used to seeing.

Here in PA, we have used ethanol blended gas for a few years to meet clean air standards. If I bought gas in PA, I got 22-24mpg. If I bought gas in West Virginia, I got 24-26mpg.

[tackepj]

I'll bet there's nothing wrong with your Vue.

Last year, the EPA banned the used of MTBE as an oxygenate in fuel. It was used to reduce the vehicle emissions, but remained in tact after the combustion process and was being washed into water supplies every time it rained. MTBE is a known carcinogen.

The EPA mandated a percentage blend of ethanol into every grade of fuel sold in the US as a replacement for MTBE.

10% Ethanol blended fuel will reduce your overall fuel economy.

Compounded with the ethanol is the use of 'winter blend' gasoline. It is reformulated during the winter months to improve the combustability and improve the cold start.

The reformulated fuel burns more easily, and does not deliver the same economy that you would see from 'summer blend' fuel.

It is likely that your economy will recover come spring, but the new ethanol blends will not give you the same economy that you are used to seeing.

Here in PA, we have used ethanol blended gas for a few years to meet clean air standards. If I bought gas in PA, I got 22-24mpg. If I bought gas in West Virginia, I got 24-26mpg.

Your assessment of ethanol's replacement, MTBE, is most likely correct in terms of reduced mileage.

However, MTBE is actually not a known carcinogen. The WHO has maintained that enhanced exposure (much more than concentrations found in water supplies) may lead to other health problems, but it is not carcinogenic.

Strange, considering the other components of gasoline. Benzene is absolutely a known carcinogen, and makes up a significant fraction of gasoline...

[FlyboyTR]

Thanks for the input. The air filter is OK. It is a K&N and is clean. Again, my mileage went from around 30 MPG ( I have the V-6) to 17-19 MPG. It has remained constant for 63,000 miles... and when the change happened it was sudden. Our fuel here on the Gulf Coast doesn't really change with the seasons. During the past 3,000+ miles the MPG has remained low. Again...I'm totally stumped! Help! Thanks.

:)

[Bill Murray]

I'm stumped....but there are a lot more knowledgeable guys here than I am....

does it seem to run like it did previously (power/driveability)?

stop by an AutoZone or equivalent and have them do a code check for any inactive codes

maybe a new set of sparkplugs?

[mangler66]

My money is on a bum O2 sensor. When mine went on my 98 contour, it was a while before the code showed up. If you get a rottent egg smell from the car, its probably time for new plugs. Actually, at 50k miles, it would not hurt. Although plat plugs will "fire" at 100k miles, you do see a signififanct difference in performance when you replace at 50-60K.

[FlyboyTR]

I use a Scanguage all the time. No codes have shown up. ...for whatever that's worth!:)

I will give the spark plug change a go and see what happens. We're leaving in 3 days for a ski trip...probably around 1400 miles. That should be a good test to see if it helps! Thanks again!

Flyboytr :usa:

[lockergnome51]

My last car that was not a saturn, did that i had the fuel filters changed and that improved it quite a bit. I'm wondering if its that simple fix. I believe it costed me like 60 bucks and improved my mileage tremendously.

[Bullet]

My last car that was not a saturn, did that i had the fuel filters changed and that improved it quite a bit. I'm wondering if its that simple fix. I believe it costed me like 60 bucks and improved my mileage tremendously.

What he said, could very well be fuel filter.

BulleT
:drool:

[hasitha]

All of us should be affected by the ethanol issue. All we saw was may be 2mpg drop (27mpg to 25mpg in city driving) for our 2.2L 5sp Vue (60k). Unless the V6 is a lousy engine, something else must be wrong.

[FlyboyTR]

OK...I changed the plugs using the OEM NGK plugs. Over a 1300 mile trip I averaged 20.5 MPG. Still a long way from the 30 MPG I was getting. I wonder if the Saturn dealer may be of some help? If not...I have a beautiful Vue for sale.

[Bill Murray]

In my experience your 30 mpg was well toward the highest anyone reports.
And 20 mpg is on the low side (for highway cruise). So something has changed.

The Honda powered Vues always seem to have a perfectly clean tailpipe.
Does yours show any discoloration now?

Here's the Service Manual section for "Poor fuel economy":

DEFINITION: Fuel economy, as measured by an actual road test, is noticeably lower than expected. Also, the economy is noticeably lower than it was on this vehicle at one time, as previously shown by an actual road test.

Preliminary Checks
• Refer to Diagnostic System Check - Engine Controls .

• Refer to Symptoms - Engine Controls .

• Check the air cleaner element for dirt or restrictions.

• Visually and physically check the vacuum hoses for splits, kinks, and proper connections as shown on the Vehicle Emission Control Information label.

• Check the owners driving habits for any of the following:

- The A/C system defroster mode is ON all the time.

- The tires are improperly inflated.

- Heavy loads are frequently being carried.

- Heavy acceleration and high speeds are common.

- Frequent short trips

- Prolonged periods of idling

- Driving on unpaved or rough roads

• Suggest that the owner refill the fuel tank and recheck the fuel economy.

Fuel System Checks
• Check the type, quality, and alcohol content of the fuel. Oxygenated fuels have lower energy and may deliver reduced fuel economy. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

• Check for the correct fuel pressure. Refer to Fuel System Diagnosis .

Ignition System Checks
• Inspect the spark plugs for correct operation and good ignition system performance. Refer to Spark Plug Inspection .

• Check the ignition coil boots for cracking, chafing, and loose connections.

• Observe the Spark parameter on the scan tool at idle, while operating the rear defogger, the A/C system, or the headlights.

• Check the knock sensor (KS) and the sensor circuit shielding. A faulty knock sensor or signal interference could cause excessive retard of the ignition timing advance. Observe the Spark parameter on a scan tool and compare with a known good vehicle.

Cooling System Checks
• Check for the correct engine coolant level.

• Check the engine thermostat for always being open or for the wrong heat range. Refer to Thermostat Diagnosis in Engine Cooling.

Additional Checks
• Check the transmission shift pattern and the torque converter clutch (TCC) operation in vehicles equipped with an automatic transmission. Refer to Symptoms - Automatic Transmission in Automatic Transmission.

• Check for dragging brakes. Refer to Brakes Drag in Hydraulic Brakes.

• Check for uneven or premature tire wear. A suspension misalignment can cause reduced fuel economy. Refer to Measuring Wheel Alignment in Wheel Alignment.

• Verify that the tires and wheels are similar to OEM. Wide performance tires create more drag and taller tires can cause odometer discrepancies.

• Check for the speedometer for proper calibration. Refer to Speedometer and/or Odometer Inaccurate or Inoperative in Instrument Panel, Gages, and Console.

• Check for a green engine. Fuel economy may not be near expected levels until the engine has had 5 000-8 000 km (3,000-5,000 miles) to break in.

• Check for add-on equipment like luggage racks and carriers. Wind resistance can lower fuel economy.

• Check the Service Bulletins for any updates or information.

[nakman]

Any recent mods? Cosmetic or otherwise? Just wondering if there is additional drag.....new tires? Plastic side window vents, rear spoiler, roof rack etc......

The performance hasn't changed at all in the slightest? Maybe the actual injectors are a bit clogged. You just returned from a tour of duty, was the VUE sitting while you were gone? Maybe you have a slightly ceased brake caliper or rear brake cylinder? Still works fine but, doesn't retract......Just stretching........:(


Or maybe you've changed your driving habits after scooting around in other vehicles "over there"........:eek: :sneeze: :tounge:

Hope you find out the cause......:yes:

[1saxman]

Good stuff, Bill!

[mellissam]

Good stuff, Bill!

Ditto....
Somone mentined that if you pull the battery leads for a half hour or so, it will reset the ECM (?) Fact or fiction?
It was in response to me adding a K&N filter and de-bonging.....

[BobbyP]

Ditto....
Somone mentined that if you pull the battery leads for a half hour or so, it will reset the ECM (?) Fact or fiction?
It was in response to me adding a K&N filter and de-bonging.....

We all know what rotten gas mileage that over powered Honda engine gets...

[mellissam]

We all know what rotten gas mileage that over powered Honda engine gets...

LOL, you said it, not me....:yes:
I was just suggesting, that perhaps resetting the ECM might help....or maybe it is bunk....??

[BobbyP]

LOL, you said it, not me....:yes:
I was just suggesting, that perhaps resetting the ECM might help....or maybe it is bunk....??

I only get 23 mpg city and 32 mpg on the highway...