# Turbo issue leading to poor MPG



## 2011CruzeECO6SPD (Jul 16, 2015)

So to start out I bought my 2011 Cruze ECO 6spd with 57K miles at an Insurance auction due to deer damage around 6 months ago. I replaced the hood, radiator, condenser, intercooler and headlights and misc plastic. 
When I purchased the car I was rather excited when I clicked thru the information center and the car was getting 46.4 MPG and had 490 miles on the trip. The red light was on for it being nearly outta gas but the math all added up between the trip and the miles. 
That being said since I've had it all back together the best I'm getting is around 35/37 mpg avg if I'm lucky. I drive 2 hrs back and forth to work each day with the cruise set on 61 mph. All 2 lane hiway. 
What I am noticing is a severe vibration when I slow at a stop light or stop at the sitters to pick my boy up. It quits finally about a block down the road. The vibration shakes the mirror in the car and passengers can feel it as well. I can rev the engine up and watch the tach and it runs smooth as silk but it seems the turbo might be the issue. To me it doesn't have the go it should either when you pull out to pass someone or up a hill. I have to down shift quite a bit it seems. 
What I'm wondering is, with the intercooler being unhooked while I was working on the car and driving it in and out of the shop while I was repairing it, did that possibly damage the turbo? Is it damaged and not working correctly making the engine work harder so the mileage is crap?
Or did the guy before me have a magic right foot to get that miracle gas mileage?

Something is clearly not right with the car and the severe vibration I feel and hear could be the culprit...............


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## ChevyGuy (Dec 13, 2014)

2011CruzeECO6SPD said:


> with the cruise set on 61 mph. All 2 lane hiway.


Try slowing down. Aerodynamic drag starts taking it's toll at speeds much above the highest gear.

It's also possible the prior owner had a trip coming down the mountain. Hills can also mess with your mileage.

I'm not sure what's causing your vibration. A few have reported problems with the dual-mass flywheel. It creates a vibration at engine idle, but the engine runs fine. The dual mass flywheel isolates the vibration inherent in a 4-stroke 4-cylinder engine from the output shaft.

But you should rule out other problems first, as low RPMs can expose a number of problems.


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## Patman (May 7, 2011)

I have a 2012 Eco with 52K on the clock and depending on how I drove the car prior to refilling, it will display similarly. I believe mine is up to 470 after refilling when I drive a lot on the highway. I know my car the front brake calipers were seemingly locked so I was driving around with my brakes on all the time and I was getting in the high 20s. You have replaced most the front end, was the car aligned properly? Evidently something happened from hitting the deer but to say what it is would depend on several things: How are the spark plugs with that much mileage and what type of gas are you running 87 /89 or 91/93? How does the car idle(rough)? Do you hear the turbo kicking in a lot or not at all?


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## 2011CruzeECO6SPD (Jul 16, 2015)

The other day I pushed my car forward with ease (I was mowing and didn't want to walk up to the house and get the keys lol) so I don't think its a brake issue. The damage to the car was above the front bumper so alignment wouldn't be an issue. One of my first instincts was to replace the spark plugs. When I got in there it had an NGK plugs in it so I knew that had been done already. But with my driving the car in and out of my garage a few times with the air box off the car I decided to go ahead and replace them incase there was any air/fuel ratio problems with the air box off. I went with an AC Delco Irridium plug. They were pretty spendy and I closed the gap up or opened it up (which ever they said on here would increase fuel economy) just a hair. I have experimented a lot with gas as well. I live in Iowa so Ethanol is a huge deal around here. I will sa,y when I run an ethanol blend my MPG is poor. Its best with Premium. In general the car idles great. Even seems to idle fine when the huge vibration starts. Seems the turbo will zip right along in the lower gears through town but in 5th/6th gear on the highway when lugging the motor it seems the turbo does nothing. Has minimal boost it feels. I'm also having to shift down to 5th gear and sometimes 4th to get around people to pass or on hills. Like I said I live in Iowa so its not mountainous or real hilly for the most part. Pretty flat and lots of corn!


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## 2011CruzeECO6SPD (Jul 16, 2015)

I have also pumped up the tires to 40 PSI.


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## 30 Ounce (Nov 18, 2012)

They came from the factory with NGK plugs do those may be the originals. Just pushing the car in the driveway won't determine if you have a dragging caliper. The brake system will expand with heat and drag more the hotter they get. When I installed rear discs on my Z I had the master cylinder miss adjusted and it would drive for 2 miles and completely lock up the rear wheels. But when they were cold everything seemed fine. Find your vibration and fix it. I think that's related. My ECO gets 42-45mpg at 65 mph. If your highway speed is 61 then you will need to downshift to pass. I think that's about 1800 rpm's and boost doesn't really start building until 2000-2100rpm's.


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## obermd (Mar 3, 2012)

2011CruzeECO6SPD said:


> So to start out I bought my 2011 Cruze ECO 6spd with 57K miles at an Insurance auction due to deer damage around 6 months ago. I replaced the hood, radiator, condenser, intercooler and headlights and misc plastic.
> When I purchased the car I was rather excited when I clicked thru the information center and the car was getting 46.4 MPG and had 490 miles on the trip. The red light was on for it being nearly outta gas but the math all added up between the trip and the miles.
> That being said since I've had it all back together the best I'm getting is around 35/37 mpg avg if I'm lucky. I drive 2 hrs back and forth to work each day with the cruise set on 61 mph. All 2 lane hiway.
> What I am noticing is a severe vibration when I slow at a stop light or stop at the sitters to pick my boy up. It quits finally about a block down the road. The vibration shakes the mirror in the car and passengers can feel it as well. I can rev the engine up and watch the tach and it runs smooth as silk but it seems the turbo might be the issue. To me it doesn't have the go it should either when you pull out to pass someone or up a hill. I have to down shift quite a bit it seems.
> ...


At 61 MPG you should be seeing ~50 MPG. The vibration at idle is possibly a broken engine mount. I would replace the spark plugs with NGK BRK8EIX gapped to 0.029" (should come at this gap but check before installing). Have the engine mounts checked, and while you're at it check for a vacuum leak. Search around here for instructions on checking for a vacuum leak.


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## jblackburn (Apr 14, 2012)

2011CruzeECO6SPD said:


> The other day I pushed my car forward with ease (I was mowing and didn't want to walk up to the house and get the keys lol) so I don't think its a brake issue. The damage to the car was above the front bumper so alignment wouldn't be an issue. One of my first instincts was to replace the spark plugs. When I got in there it had an NGK plugs in it so I knew that had been done already. But with my driving the car in and out of my garage a few times with the air box off the car I decided to go ahead and replace them incase there was any air/fuel ratio problems with the air box off. I went with an AC Delco Irridium plug. They were pretty spendy and I closed the gap up or opened it up (which ever they said on here would increase fuel economy) just a hair. I have experimented a lot with gas as well. I live in Iowa so Ethanol is a huge deal around here. I will sa,y when I run an ethanol blend my MPG is poor. Its best with Premium. In general the car idles great. Even seems to idle fine when the huge vibration starts. Seems the turbo will zip right along in the lower gears through town but in 5th/6th gear on the highway when lugging the motor it seems the turbo does nothing. Has minimal boost it feels. I'm also having to shift down to 5th gear and sometimes 4th to get around people to pass or on hills. Like I said I live in Iowa so its not mountainous or real hilly for the most part. Pretty flat and lots of corn!


What you described are pretty normal driving characteristics for an Eco IMO. Your 5th gear is 6th on the LT models. 4th-6th are all overdrive gears on an Eco.

The ACD plugs do not provide much in the way of power at low RPM either.

I am wondering if you might have a vacuum leak or dirty throttle body contributing to a low idle. When my valve cover disc went out, my car idled like a dump truck.


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## Alex V. (Sep 20, 2013)

Be sure you aren't just selling the little 1.4 short on its power curve before you look for a problem. The little engine runs great, but does not have horsepower below 2,500-3,000 RPM. My '13 LT M6 would hit 40 on the commute you described, so your gas mileage is lacking, but on the other hand if I need to get around somebody - even with the A/C off - starting from 61 MPH I'll happily go to 4th to accomplish it. The 1.4 has a good torque curve for a small 4 cylinder, but horsepower is what you feel when you pass and there's precious little of that at 2,000 RPM. 

Would you consider getting ahold of something like an Ultragauge to read your boost pressure?


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## 2011CruzeECO6SPD (Jul 16, 2015)

I have a friend that has a diagnostic scanner. I would think I could hook it up and monitor the turbo that way as I drive it. I will order NGK's today and get them installed this weekend. See if that helps any. Also I might try and back my speed down to at least 60mph. Any slower than that I will probably get ran over. The severe vibration I feel is a hit and miss deal. Some days it does it and some days it doesn't it seems. Makes it hard to find.


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## Camo66 (Jun 27, 2015)

Hi there,

firstly I would be as happy as a pig in mud if I got 35mpg. Here in Australia we have the 1.6L turbo and I only get 24mpg or 9.5L per 100km. I did a trip and only got 29mpg but wasn't constant highway driving. My car is 2015 1.6L Auto with only (equivalent) 1200 miles. 

As to your question as running engine with intercooler or airbox disconnect, it would do any damage unless you were driving on a dirty road all had very dusty conditions near engine bay at that time. And if only in your driveway, I doubt the previous comments would apply. 

I'm an older mechanic, just encase you are wondering. 

As Alex stated, you aren't driving a huge capacity engine car. I wouldn't expect it to accelerate to quick in 6th gear at 60mph unless you have about 300hp at the engine.

The engine shaking at lower rpm sounds like it could be a vacuum leak as others have mentioned. Unless injectors are really dirty and not spray good pattern at idle.

Good luck and let us know what you find.

Kev


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## ChevyGuy (Dec 13, 2014)

The PCV that's part of the valve cover is a common problem in these cars. That might be the source of running rough at idle.


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## Merc6 (Jun 8, 2013)

ChevyGuy said:


> The PCV that's part of the valve cover is a common problem in these cars. That might be the source of running rough at idle.


Might be me actually as well.


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