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Discussion Starter · #1 ·
2011 V-6 FWD Terrain: Best mileage so far on the hwy has been 22 driving 65 with 4800 miles on the clock. I expected better than that and would just be happy to get the EPA mileage.
One thing I have noticed. The tailpipes are really sooty and almost all my driving is hwy or completely warming the vehicle.
I traded in a Rendezvous with 44000 miles, and the whole time I had it the tailpipe was surgically clean. Never any soot or discoloration. Soot tells me the Terrain is running rich or something else is wrong. Service manager sez "That's normal".
Is it?
 

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My chrome tips are also corroded and dirty almost rusty. Never had that problem with any other chrome tips.

My advice is don't spend money to add chrome tips....not worth it.
 

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I've got 31,000 on my 2010, and the chrome tips look new. Maybe a local/climate issue where you are?
 

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Chicago area...even so the tips on my Aztek didn't corrode like these did.
 

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Discussion Starter · #5 ·
My tips aren't corroded or anything like that. The inside of the tips and tailpipes are sooty, and if I go a long time between washing, it even gets sooty looking in the cutouts in the rear "bumper".
The inside of my Redezvous tailpipe stayed clean, even at 44000 miles. Surgically clean.
In the "good old days", this meant either you were running very rich or burning oil like crazy.
Another thing I've noticed since it was new is that it now does a lot more downshifting on grades than it did initially. This is while in cruise control.
I'm a very conservative driver, never jackrabbit, most driving is on the highway or if in town vehicle is completely warmed up, etc.
What bothers me is that I had two Buick LeSabres, a 90 and a 99 that consistently got over 30 MPG on the highway and with a bigger engine.
I hope this gets better or I find a service manager who doesn't tell me "that's normal".
 

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The best fuel economy possible is the direct result of proper maintenance and good driving habits. Listed below are GM's recommendations to achieve the best mileage possible. The first group includes things to consider for your vehicle, while the second are tips relating to your driving habits.

1. Always keep your tires inflated to the proper pressure as shown on the vehicle placard. This not only serves to increase gas mileage but cuts down on tire wear, further decreasing your costs per mile.

2. A vehicle that has a dirty air filter can’t efficiently draw air into the engine. This restriction forces the engine to expend energy to "breathe" wasting fuel in the process. Change recommendations are found in your vehicle Owner’s Manual.

3. Always use the proper viscosity oil in your engine. Oil that has a higher than required viscosity will create more drag on the internal components of the engine causing more work for it, especially when cold. Each Owner’s Manual contains information on the proper type of oil for your vehicle. Look for the "starburst" symbol on the front of the bottle, and the SM rating on the API circle on the back label. If you are in doubt, stop by your dealer for an oil change, and any other services required. Most current GM vehicles are equipped with oil life monitors to further assist on the "when" to change your oil.

Note: GM Vehicles DO NOT require additional engine oil additives. Some additives may cause harmful effects to the internal seals and additionally void the terms of your vehicles New Car Warranty.

4. Top Tier Detergent fuels are preferable when and where available. They help to keep your fuel injectors and intake valves free of deposits. When Top Tier fuels are not available, consider a bottle of GM Fuel System Treatment PLUS, P/N# 88861011 (in Canada, #88861012), at oil change time which will remove intake system and injector deposits. GM does not recommend any other fuel system cleaner.

Note: DO NOT confuse Top Tier Fuels with Higher Octane (Plus/Premium Grade Fuel) commonly sold at most all gas stations.

5. Using higher octane fuels in a vehicle that only required regular unleaded fuel will neither increase performance nor improve gas mileage. In all cases refer to your owner’s manual and ONLY use the octane rated fuel recommended for your vehicle.

Note: In high performance GM vehicles that DO require Premium (91 octane or higher) fuel, you MUST use fuels of at least this octane.

6. Is the Check Engine/SES light on? When the computer lights the Check Engine/SES light it has lost some ability to run efficiently. This may result in increased fuel consumption, increased emissions, and/or drivability concerns.

7. Even though current GM vehicles have 100,000 mi (160,000 km) service intervals for spark plugs if your vehicle is at that point in its life, have the spark plugs changed to assure proper running and continued efficient, trouble free operation.

8. Avoid quick/full throttle acceleration from a standstill in town and high cruising speeds on the interstates. While the optimum MPG for highway cruising speed varies from vehicle to vehicle, faster is almost always worse. If your vehicle is equipped with a Driver Information Center that displays Instant Fuel Economy, select that readout and vary your cruising speed while on the highway. The display will change continuously with uphill and downhill sections but you should quickly be able to identify on level ground the speed range that your vehicle does the best in.

9. Avoid leaving unnecessary items in your trunk. It takes power to move increased weight and that means more gasoline consumption and reduced performance. While the change may be slight, multiplied by thousands of miles, it all adds up.

10. Idling wastes fuel.

11. Your vehicle uses much more fuel when the engine is cold. This is especially true in the winter months when the engine will take the longest to warm up. Combine errands or trips so that the vehicle only needs to warm up once to encompass many different stops.

Regarding the tailpipe, I would have to agree that this would depend on the conditions in which you are driving. If you have further questions or concerns, please feel free to contact me directly. Thank you.

Tricia, GM Customer Service.
 

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Im a very conservative driver to get best mpg and i noticed the soot in my tailpipe on day 4 of having the vehicle. My mazda however. The tailpipe is super clean and its a 07 with 70k on it. I do believe my nox is running rich. I mentioned that to my dealer with 400 mi on it and he ignored that fact and gave me the breake in lecture. Again its hard to get a mechanic to acknowledge any issues or look into it if rhe car actually drives and of course they say if the check engine lite is not on then theres nothing wrong. Blahhhhh
 

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I do or have all the above with the exception that i keep my tires a couple pounds higher for better mpg. When I use to do economy runs we would inflate the tires to at least 60psi some went higher. We had cars getting close to 100 mpg back then. Now only getting 15 mpg is unacceptable. I'm going to have to bring it in and see what they can find out.
 

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Soot on tailpipes, etc.:

With OBDII diagnostics, catalytic converter efficiency, multiple oxygen sensors, and governement mandated test routines - it would be pretty tough for a vehicle to run rich and not throw a trouble code. If you could see all of the OBDII test routines and diagnostics that run on the vehicle - you could see this is not the days of throttle body injection and carburetors.

Also, remember that the tailpipe is way at the back of the vehicle - where the least amount of heat from the exhaust will be. Depending on outside temperatures, length of time running, engine speeds, etc. - will affect the amount of condensation or deposits on the tailpipe exits. Additionally, diameter of tailpipe, number of outlets, and engine size will affect it due to exhaust gas velocity. A single, small diameter pipe will have much greater exhaust velocity and also residual heat than one or two larger outlets especially on a smaller engine. The Terrain and Equinox have a fairly large diameter exhaust system (less restrictive) than even some V-8 vehicles I have owned with engines over twice as large.

While the existence of deposits or "soot" on the tailpipe outlets are probably nothing to worry about, as always, if you have a concern, you should discuss it with your dealer service department for proper diagnostics.
 

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Mine looks rather excessive. I wonder if you test for emmisions the old way(directly from tail pipe) if it would pass. I dont think it would(hence probably why i have a excempt sticker) :thumb:
 

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GARYD said:
I do or have all the above with the exception that i keep my tires a couple pounds higher for better mpg. When I use to do economy runs we would inflate the tires to at least 60psi some went higher. We had cars getting close to 100 mpg back then. Now only getting 15 mpg is unacceptable. I'm going to have to bring it in and see what they can find out.
I am glad to see that you are planning to bring this to the attention of your dealership. Please keep us posted.

Tricia, GM Customer Service.
 

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pacman said:
Mine looks rather excessive. I wonder if you test for emmisions the old way(directly from tail pipe) if it would pass. I dont think it would(hence probably why i have a excempt sticker) :thumb:
I'm not aware of any other way to perform that part of the emmisions test except via the tailpipe.

And although it's not a Nox / Terrain, our Throttle body 2004 Chevy Avalanche has always had a sooty exhaust. It's now 7 years old with 68,XXX miles on it and has passed California's "rigid" tailpipe test twice with flying colors...each time on the lower portion of "center slot".

I mention my other Chevy because it pains me to hear complaints of sooty tailpipes with no other symptoms.
It is what it is...in the absence of a SES/MIL lamp and/or a "Drivability" issue...IMHO it's a lot of worry over nothing.

If you are really concerned...treat it like sending out an oil sample...and go have your vehicle emission tested needed or not...at least the result will confirm an issue or put your mind at ease.

I'll also point out that during cold start...when the engine is in "closed loop"...it is much more likely to deposit soot in the tailpipe...so you have to balance what you "see" with the when, why and what is actually happening.
 

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pacman said:
Im a very conservative driver to get best mpg and i noticed the soot in my tailpipe on day 4 of having the vehicle. My mazda however. The tailpipe is super clean and its a 07 with 70k on it. I do believe my nox is running rich. I mentioned that to my dealer with 400 mi on it and he ignored that fact and gave me the breake in lecture. Again its hard to get a mechanic to acknowledge any issues or look into it if rhe car actually drives and of course they say if the check engine lite is not on then theres nothing wrong. Blahhhhh
I would also recommend waiting a couple thousand miles to have the vehicle broken in properly. However if you feel that this is the result of some concern, I would recommend taking the vehicle back to the dealership. The fuel economy estimates are based on results of tests required by the U.S. Environmental Protection Agency (EPA). These tests are used to certify that vehicles meet the federal emissions and fuel economy standards. The vehicles are driven by a professional driver under controlled laboratory conditions, on an instrument similar to a treadmill. These procedures ensure that each vehicle is tested under identical conditions; therefore, the results can be compared with confidence. Please keep in mind that these ratings are estimates. Feel free to keep me posted in regards to your concern.

Tricia, GM Customer Service.
 

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Fyi. I brought the nox in at 400 mi cause of the strong smell in oil while back. I now have 2k on it. Getting even lower mpg now.(19) no gas smell but still lots of soot. Sometimes the car feels like its loosing power on acceleration. Im planning to address the issues when i go in for my 1st oil change
 

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pacman said:
Fyi. I brought the nox in at 400 mi cause of the strong smell in oil while back. I now have 2k on it. Getting even lower mpg now.(19) no gas smell but still lots of soot. Sometimes the car feels like its loosing power on acceleration. Im planning to address the issues when i go in for my 1st oil change
Please feel free to let me know how it goes at the dealership. I hope to hear from you then. Thank you in advance.

Tricia, GM Customer Service.
 
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