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I have a 2013 Impala LT. I usually baby this car quite a bit (almost never sees over 3K rpm) which I'm thinking may be part of the problem. Yesterday I went to pass someone, and got on it pretty good. As the RPM climbed over 3000, the engine started having almost flat spots of power, followed by a huge increase, and would do this surging up to about 5000 where I got off the gas. I found it strange as I never felt that when I bought it, so this was something new. Once I got onto back roads and away from traffic, I did it a few more times. Each time the surging was less and less, till eventually it went completely away and it pulled hard and smooth out to 6K.


Anyone else notice this before? Do these cars just need to be run hard every once in a while? Or does this sound like a different problem? I am due to pull my throttle body apart and clean that out some. Car has 58K miles btw.
 

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I have a 2013 Impala LT. I usually baby this car quite a bit (almost never sees over 3K rpm) which I'm thinking may be part of the problem. Yesterday I went to pass someone, and got on it pretty good. As the RPM climbed over 3000, the engine started having almost flat spots of power, followed by a huge increase, and would do this surging up to about 5000 where I got off the gas. I found it strange as I never felt that when I bought it, so this was something new. Once I got onto back roads and away from traffic, I did it a few more times. Each time the surging was less and less, till eventually it went completely away and it pulled hard and smooth out to 6K.
Anyone else notice this before? Do these cars just need to be run hard every once in a while? Or does this sound like a different problem? I am due to pull my throttle body apart and clean that out some. Car has 58K miles btw.
My 2013 Impala LTZ was experiencing a similar situation when I first bought it used as a certified pre-owned. It had 59,000 miles on it when I bought it. This typically happens for me when I was merging onto the Interstate and the revs were getting up around 3000 rpm. In my situation it turns out of that over that many miles I had some oil build-up in the intake tube and throttle body and intake manifold that was causing my problem. Since it was still under warranty I took it to the Chevy dealership and they cleaned those three items out. After that was taken care of the car has been running fine experiencing no hesitation whatsoever. As I have been reading up on this on this forum apparently this is a situation that is common with direct injection engines and needs to be followed up on from time to time. That was my experience I hope that helps.
 
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The ecm learns how you drive and changes things accordingly. If you want to erase all that you can disconnect the negative battery cable for 5 or 10 minutes. Hook it back up and drive it like you stole it for the next few days. This will give it a new learn cycle and set engine parameters accordingly.

You felt it starting to "relearn" as you drove it as you described.

That's what I think is going on.

Others may have different views.
 

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My guess is the surge you felt was the variable valve timing kicking in (e.g. it switched to its more aggressive cam profile). Every time I hit VVT I notice a surge of power, and it doesn't just occur at a specific rpm (think Honda's V-TEC), the ECM selects for it based upon throttle position, speed, etc. Makes predicting acceleration tricky at times.

This is only my best guess based upon what you've stated. I have a '13 LTZ, and keep it below 3k rpm until the coolant has been at temp for a few minutes, then the whole rev range is fair game.
 

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Discussion Starter · #5 ·
In my situation it turns out of that over that many miles I had some oil build-up in the intake tube and throttle body and intake manifold that was causing my problem. Since it was still under warranty I took it to the Chevy dealership and they cleaned those three items out. After that was taken care of the car has been running fine experiencing no hesitation whatsoever.
This is what I was thinking. I'll get around to checking that out sometime soon hopefully.
The ecm learns how you drive and changes things accordingly. If you want to erase all that you can disconnect the negative battery cable for 5 or 10 minutes. Hook it back up and drive it like you stole it for the next few days. This will give it a new learn cycle and set engine parameters accordingly.
If I notice the car seems to be doing this again, I may try disconnecting the battery and resetting it, to see if the issue immediately goes away. Would be a good way to tell if it is a computer thing or a mechanical issue.
My guess is the surge you felt was the variable valve timing kicking in (e.g. it switched to its more aggressive cam profile). Every time I hit VVT I notice a surge of power, and it doesn't just occur at a specific rpm
That could be...although it doesn't quite feel like all of a sudden I'm getting way more power. It feels like I lose power for a brief second, than get it back. Almost like its stumbling. Maybe I didn't word the original post the best. And it does it multiple times in one pull through the RPMs. It also smoothed out after doing about 4 hard pulls to 5K+ rpm.
 

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Hmm... you may just want to make a habit of letting everything warm up, and then going to the upper rev range once every few days or so. Your issue may no longer be one. My '13 has 71k miles and I don't have any stumbling or power loss issues. Granted a lot of my mileage is highway.
 

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I wouldn't call it a computer issue , it's just that the ecm/pcm learns driving patterns. Maybe not drive it quite like you stole it but more like you rented it. Then once in a while give her a good hard pull onto the highway like Josh says.
 

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Mine felt more like when the gap on your spark plugs grow too wide and you get that stumbling from spark plug blow out.
 

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I've never encountered a stumbling acceleration on this car except for when my purge valve went bad (only occurred after cold starts when slowing down to a stop), but that's a different issue. Without a better description (or a decent video), it's hard to do anything aside from speculate about the issue the O.P. has. Hopefully it's something simple though.

On a side note, don't be afraid to give that 3.6 the goods every now and then. It was designed to operate safely up to 6500 rpm once at normal operating temperatures. Please don't use less than half of the rev range the entire lifetime of the car.
 

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Only reason I suspect drive pattern is he said he never goes over 3000 rpm and babies it.

Like you said. "Give er the beans" now and then
 
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