Engine stutter and general power loss

[C.E.Divine]

I have a 2013 sonic, 1.4 turbo with 64k miles. The last week or so I have noticed the engine stuttering between 1500 and 3000 rpm. It doesn't feel right through the whole range and acceleration is jerky, but the stutter is most pronounced in that range while under load in 6th gear. Which is a problem, because I drive 100 miles in that exact range each day.

I've been racking my brain about what this could be, including tune-up. A tune up with plugs and all filters didn't fix the issue.

One thing that occurred to me today as I was watching my ultra gauge is that the car never boosts over 11.5 psi, and never seems to spool up as I increase load. Is it possible that my BOV is having a pre-load issue? I am not throwing the p0299 code, but what is considered the threshold for the light to actually throw versus when you start to notice a problem with degrading performance over time?

I'll be happy to provide any additional info I can to help diagnose the problem. I drive too much each day to put up with this car being gutless any longer.

 

[Natesriv]

1500 RPM in 6th is way below any noticeable acceleration......

Is this a 6th gear only issue ?

 

[C.E.Divine]

No, it is just most noticeable in sixth because of the slow acceleration. it exists in the rest of the gears as well. And to be honest, I may say it is most pronounced between 1500 and 3000 only because that is where i spend most of my time. It is jerky through the whole rpm range though.

 

[C.E.Divine]

And another hint, it is only jerky at full throttle. When I let off and coast the jerking ends, and it only really starts when I go beyond half throttle and up to putting my foot through the firewall.

 

[spacedout]

How hot has it been where yo live? What octane fuel are you running? Anything above 80F outside regular 87 octane really starts to rely heavily on the knock sensor to dial things back and you will feel less power. It also doesn't help most of us are running the AC as well, you can feel the loss of power as soon as you engage it. My car seem to need to rev higher with the AC on just to get that same power feel as normal.

 

[C.E.Divine]

I'm running 93 octane with no ethanol. It's not a knock or ac power draw issue. I know that much. This feels different that timing retardation.

 

[Natesriv]

You have a stock 1.4? If so it's a bypass valve, not a blowoff valve... If it was sticking open or not sealing all the way it COULD be something to look at... it's a PITA to get to, need a long screwdriver (keep a magnet handy)...3 screws...

Also, check your airbox and airbox hose to the engine to ensure there's no tears or openings... could be tricking your MAF sensor.... might clean the MAF sensor with an electrical cleaner which leaves no residue...

besides that I'd check the valve cover for any signs of cracks... I think our PCV's are integrated into the valve cover...

Then there's our good friend...the coil pack. Not sure if you can replace single parts or it needs a whole new coil pack......

 

[spacedout]

I'm running 93 octane with no ethanol. It's not a knock or ac power draw issue. I know that much. This feels different that timing retardation.

Your description of jerky acceleration(not smooth) is exactly what it feels like when the car is riding the knock sensor, almost as though the power curve is stepped and not a curve. When you are trying to accelerate this stepped feeling almost feels like the car stops for a millisecond at each increase in 100-200 increase in RPM.

From all my testing these cars like fuel with 10% ethanol, without I get way more knock events(both my 2012 cruze and 2015 sonic are this way). I would try a different stations fuel, I've had more than one brand 91/93 run like crap compared to other brands. This is more noticed with high outside temperatures, not all fuel is created equal.

 

[zippypcs]

When you had the plugs out, did you happen to look up into the coil boots?
I would check the boots for any sign of oxidation.
They will be a greenish color possibly inside on the spring part. This happened to mine already once at 50k.
The 1.4t is known to have this problem.

 

[spacedout]

I noticed besides the little spring inside the boot sometimes getting corroded, the spring can get wedged into the side of the boot so only part of the tip is making contact with the plug. This causes weak spark and hesitation. If you find any this way make sure to use a small screw driver to pop them back straight before you put the coil pack on.

Look carefully to ensure you don't have any rips in the plug boot, very easy to rip when removing the coil pack, this can also cause hesitation.

 

[Chevrolet Customer Care]

I have a 2013 sonic, 1.4 turbo with 64k miles. The last week or so I have noticed the engine stuttering between 1500 and 3000 rpm. It doesn't feel right through the whole range and acceleration is jerky, but the stutter is most pronounced in that range while under load in 6th gear. Which is a problem, because I drive 100 miles in that exact range each day.

I've been racking my brain about what this could be, including tune-up. A tune up with plugs and all filters didn't fix the issue.

One thing that occurred to me today as I was watching my ultra gauge is that the car never boosts over 11.5 psi, and never seems to spool up as I increase load. Is it possible that my BOV is having a pre-load issue? I am not throwing the p0299 code, but what is considered the threshold for the light to actually throw versus when you start to notice a problem with degrading performance over time?

I'll be happy to provide any additional info I can to help diagnose the problem. I drive too much each day to put up with this car being gutless any longer.

Hello C.E.Divine,

We're sorry to hear you're experiencing engine concerns with your Sonic. I understand you're seeking advice from fellow forum members, however, if you decide to take it into your dealership for a diagnosis, please feel free to send us a private message if you'd like assistance.

Have a great day!

Chelsea D.
Chevrolet Customer Care

 

[C.E.Divine]

Your description of jerky acceleration(not smooth) is exactly what it feels like when the car is riding the knock sensor, almost as though the power curve is stepped and not a curve. When you are trying to accelerate this stepped feeling almost feels like the car stops for a millisecond at each increase in 100-200 increase in RPM.

From all my testing these cars like fuel with 10% ethanol, without I get way more knock events(both my 2012 cruze and 2015 sonic are this way). I would try a different stations fuel, I've had more than one brand 91/93 run like crap compared to other brands. This is more noticed with high outside temperatures, not all fuel is created equal.

I will revisit timing and fuel then. My truck feels way different when the knock sensor kicks in, but I guess I shouldn't be so quick to rule it out.

 

[C.E.Divine]

When you had the plugs out, did you happen to look up into the coil boots?
I would check the boots for any sign of oxidation.
They will be a greenish color possibly inside on the spring part. This happened to mine already once at 50k.
The 1.4t is known to have this problem.

Coil boots and springs are all fine. I went through that problem already, haha. Ripped a boot changing spark plugs, and had to find something to work. A boot from a ford modular v8 truck engine is able to be trimmed and fit almost like the factory boot. Then I got the springs in there ****-eyed and had a misfire for a while. I was on a couple hundred mile trip and didn't have any tools with me to pop the coil off.

 

[Natesriv]

I hadn't thought about the knock sensor, but I think he's running high octane no ethanol...

hmmmmmm

 

[spacedout]

I hadn't thought about the knock sensor, but I think he's running high octane no ethanol...

In Wisconsin most stations sell 91 octane no ethanol for premium, I have to go out of my way to get 93 octane with 10% ethanol. The reason I do is because the no ethanol fuel causes knock with both my 2012 cruze and 2015 sonic 1.4T. Typically this is felt at low RPM high load situations(between 1500-2500). High load could be even the slightest grade change at low RPM or even just stepping the throttle down to accelerate.

In Wisconsin Mobil, Shell, BP, Cenex(all top tier stations) will have either grade of premium, even stations less than 10 miles apart will have different grades to premium. There is a couple Shell and Mobil stations that sell both 91E0 and 93E10 on the same pump.

I tested my MPG off the same pump comparing grades, I only got a 0.8MPG improvement running the no ethanol fuel over thousands of miles tested.

 

[C.E.Divine]

In Wisconsin most stations sell 91 octane no ethanol for premium, I have to go out of my way to get 93 octane with 10% ethanol. The reason I do is because the no ethanol fuel causes knock with both my 2012 cruze and 2015 sonic 1.4T. Typically this is felt at low RPM high load situations(between 1500-2500). High load could be even the slightest grade change at low RPM or even just stepping the throttle down to accelerate.

In Wisconsin Mobil, Shell, BP, Cenex(all top tier stations) will have either grade of premium, even stations less than 10 miles apart will have different grades to premium. There is a couple Shell and Mobil stations that sell both 91E0 and 93E10 on the same pump.

I tested my MPG off the same pump comparing grades, I only got a 0.8MPG improvement running the no ethanol fuel over thousands of miles tested.

That's interesting about knock with non-ethanol premium. It makes sense, since I believe ethanol and methanol
burn cooler than straight gas. I just put in a tank of e10 91, and will see how that does after I've used it up by tomorrow, haha. 400 mile work trip coming up.