High fuel consumptio, low RPMs while stopped and more.

B

Bondiol

New member
Hi all,

I'm having some issues with my Chevy Sonic LT 2016 1.8. The gas consumption is higher than normal and the car shakes when I'm waiting at a red light).

I have already changed the O2 sensor, spark plugs, coil, and the service has performed injectors cleaning... but nothing helped.

Some days idling RPMs are at 650, others at 800 (The car feels better at 800 but the gas consumption is still pretty bad).

I have no fault codes or lights, but the test results on torque show some bad (weird?) stuff. Attaching image.

https://imgur.com/a/knclXE6

Does anyone have any idea what could be happening?
 
G

Gobinator98

Member
Bondiol said:
Hi all,

I'm having some issues with my Chevy Sonic LT 2016 1.8. The gas consumption is higher than normal and the car shakes when I'm waiting at a red light).

I have already changed the O2 sensor, spark plugs, coil, and the service has performed injectors cleaning... but nothing helped.

Some days idling RPMs are at 650, others at 800 (The car feels better at 800 but the gas consumption is still pretty bad).

I have no fault codes or lights, but the test results on torque show some bad (weird?) stuff. Attaching image.

https://imgur.com/a/knclXE6

Does anyone have any idea what could be happening?
Click to expand...


Them readings for the o2 sensors are normal. Try looking at your fuel trims(short and long @ idle) and reply back with what they are.


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G

Gobinator98

Member
Bondiol said:
Hi! I already have the images. The long-term fuel changed every time I turned off / on the car.

https://imgur.com/a/UXjuiZ4

Thank you very much!
Click to expand...



That’s normal that it would fluctuate as it is the average of the short term fuel trim over time. Your fuel trims don’t indicate a vacuum leak which would cause excessive fuel consumption by commanding the fuel injectors to add more fuel. That in turn would cause your long term FT to be super excessive(+/-10 or more).

For example, I had to replace my pcv valve. That caused my fuel consumption to go through the roof and the computer kept adding fuel. This resulted in my long term fuel trim to reach +36% at idle if allowed to run long enough.


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B

Bondiol

New member
Gobinator98 said:
That’s normal that it would fluctuate as it is the average of the short term fuel trim over time. Your fuel trims don’t indicate a vacuum leak which would cause excessive fuel consumption by commanding the fuel injectors to add more fuel. That in turn would cause your long term FT to be super excessive(+/-10 or more).

For example, I had to replace my pcv valve. That caused my fuel consumption to go through the roof and the computer kept adding fuel. This resulted in my long term fuel trim to reach +36% at idle if allowed to run long enough.


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Click to expand...

Thank you! The 1.8 doesn't have a PCV. I didn't test the fuel trims before, but a failing MAF could cause these symptoms. I gong to try cleaning it tomorrow.
 
G

Gobinator98

Member
Bondiol said:
Thank you! The 1.8 doesn't have a PCV. I didn't test the fuel trims before, but a failing MAF could cause these symptoms. I gong to try cleaning it tomorrow.
Click to expand...


Actually it does as I have that same exact motor lol

To replace it, you’d need to replace the valve cover since it is built in to the cover.

There should be a black plastic tube going from the valve cover to the throttle body. Remove that and see if the inside is covered in a thin layer of oil. If it is, the valve is bad. If it’s dry, the valve is fine.


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B

Bondiol

New member
Gobinator98 said:
Actually it does as I have that same exact motor lol

To replace it, you’d need to replace the valve cover since it is built in to the cover.

There should be a black plastic tube going from the valve cover to the throttle body. Remove that and see if the inside is covered in a thin layer of oil. If it is, the valve is bad. If it’s dry, the valve is fine.


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Click to expand...

You are right, sorry. I will start cleaning the MAF because is easier... I hope the PCV is in good shape, I won't take out the throttle body / cover by myself...
 
Last edited:
G

Gobinator98

Member
Bondiol said:
You are right, sorry. I will start cleaning the MAF because is easier... I hope the PCV is in good shape, I won't take out the throttle body cover by myself...
Click to expand...


The little plastic tube does not require you to remove the throttle body to inspect it. It has two little clips, one on each end.

And it’s the valve body cover that you would be replacing. That’s a $100 part and takes maybe 10 minutes to change out yourself.


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B

Bondiol

New member
Gobinator98 said:
The little plastic tube does not require you to remove the throttle body to inspect it. It has two little clips, one on each end.

And it’s the valve body cover that you would be replacing. That’s a $100 part and takes maybe 10 minutes to change out yourself.


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Click to expand...

Hi, thank you again, I going to check it then. In the meanwhile, how do these MAF values look for you?

https://imgur.com/a/8tzCiKe

Edit:

There're bad news...

Is it the tube? It had the oil that there is on my finger...

https://imgur.com/a/zB052J7
 
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B

Bondiol

New member
Gobinator98 said:
I don’t know off hand about the maf sensor values but they do look similar to mine right now.

Yes that is the tube.


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Click to expand...

I bought the car 3 months ago, and I just realized the powertrain warranty is still active (only for 2 months more from now).

I took the car to a Chevy certified service and they told me "there's no problem with the car, the thing in the hose is not oil, but coolant ... it is fine". Also told me the high fuel consumption is normal in winter. They didn't even scan the car, any ideas about what can I tell him? I'm pretty new is the U.S. my English is not so good so I believe they are fooling me. For me, the car doesn't work at should be.

I'm sad ...
 
G

Gobinator98

Member
Bondiol said:
I bought the car 3 months ago, and I just realized the powertrain warranty is still active (only for 2 months more from now).

I took the car to a Chevy certified service and they told me "there's no problem with the car, the thing in the hose is not oil, but coolant ... it is fine". Also told me the high fuel consumption is normal in winter. They didn't even scan the car, any ideas about what can I tell him? I'm pretty new is the U.S. my English is not so good so I believe they are fooling me. For me, the car doesn't work at should be.

I'm sad ...
Click to expand...


Could you take a picture of the inside of the tube or your throttle body?

Ps. There is no way that is coolant. Your oil would be milky if that was the case.


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B

Bondiol

New member
Gobinator98 said:
Could you take a picture of the inside of the tube or your throttle body?

Ps. There is no way that is coolant. Your oil would be milky if that was the case.


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Click to expand...

I didn't, I only took a picture of my finger with the oil. And yes, if it was coolant the engine would be ruined.

I also showed the screen capture of the long term fuel trim values and they didn't answer me since then. I hate Chevrolet so much, I'll never buy another Chevy in my whole life.
 
G

Gobinator98

Member
Bondiol said:
I didn't, I only took a picture of my finger with the oil. And yes, if it was coolant the engine would be ruined.

I also showed the screen capture of the long term fuel trim values and they didn't answer me since then. I hate Chevrolet so much, I'll never buy another Chevy in my whole life.
Click to expand...


Same here. This is the last one I’ll ever buy.


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B

Bondiol

New member
Gobinator98 said:
Same here. This is the last one I’ll ever buy.


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Click to expand...

Hey, you've helped me a lot. I have the car with me again, just to check a few things before taking it back to service.

I am looking for more symptoms to tell them. If you don't mind, could you tell me what is the vacuum's difference between neutral and gear in your car?

At this moment my car idles (Neutral) with 19 psi, but as soon as I switch to a gear, de vacuum goes to 14 psi as much. Could the car be losing compression through the faulty PVC (I do guess so)?

Thank you, and I'm sorry to keep bothering you.
 
G

Gobinator98

Member
Bondiol said:
Hey, you've helped me a lot. I have the car with me again, just to check a few things before taking it back to service.

I am looking for more symptoms to tell them. If you don't mind, could you tell me what is the vacuum's difference between neutral and gear in your car?

At this moment my car idles (Neutral) with 19 psi, but as soon as I switch to a gear, de vacuum goes to 14 psi as much. Could the car be losing compression through the faulty PVC (I do guess so)?

Thank you, and I'm sorry to keep bothering you.
Click to expand...


Your vacuum pressure is from the MAP sensor. Mine is 8 inHg in neutral and 10 inHg in Drive. Mind you, this is at full warm-up.

The only thing that reads in psi is the fuel pump.


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