Loss of power (pleateau) while accelerating

Kerrslight · February 4, 2016

Hey guys,

Posted a question on another thread about this a while back, but I'm going to make a specific thread for this issue in hopes someone else has had this problem and had it fixed or tell me this is a normal thing.

So truck is 2014 Sierra 5.3 4x4. Only performance based mods are exhaust and a diablew tune. So the issue at question here is there are times where, usually from a slow roll, I accelerate hard and the truck gets up and goes, but then sort of "plateaus" for a second, then gets hard on it again. It almost feels to me its a shortage of fuel or air maybe? No idea. I think I have like 90-95% of TM removed when I tuned my truck as well so I don't think it's that. Could it be fuel or air related? Deposits on the valves? Bad coil pack?

I seem to notice it most when I'm rolling around a turn, lets say turning right at an intersection and then accelerate out. Truck accelerates like it should, whether its hard or soft, then feel like it loses power, then starts accelerating again. I really don't know any better way to describe it. Another problem I have is sometime when I punch it on the highway, the truck seems to stutter. If everything is normal I will get either a one or two gear downshift and truck will run, but sometimes I punch it and the truck stutters, then gets hard on it. I'm not sure, but I feel these two have something in common. I will try to record a video on my way home this afternoon and see if I can capture it.

Anybody else having this problem?

GMC207 · February 6, 2016

My 2015 does the exact same thing! Drives me insane. Need to find time to bring it in. But I know with all my other trucks, I'm going to get the "I can't replicate it". I'll have to bring it in 20 times and I just don't have time for the BS.

I read on another post somewhere it was said to be the torque converter. Not sure if it actually fixed it though.

Kerrslight · February 6, 2016

My 2015 does the exact same thing! Drives me insane. Need to find time to bring it in. But I know with all my other trucks, I'm going to get the "I can't replicate it". I'll have to bring it in 20 times and I just don't have time for the BS.

I read on another post somewhere it was said to be the torque converter. Not sure if it actually fixed it though.

You have any idea what that thread was?

GMC207 · February 6, 2016

You have any idea what that thread was?

http://www.gm-trucks.com/forums/topic/178883-shake-shudder-on-acceleration-and-cruise-pip5337-8l90-8-speed/

It's this thread. Read all the posts. There's some talk about torque converters.

muddkatt · February 6, 2016

Had that exact same problem on a Toyota Avalon, turned out to be the MAF sensor. Cleaning the sensor would help, but replacing it about every 75K miles was the only true fix that would last about 50K miles.

ic3man5 · February 8, 2016

Does it do it with traction control disabled?

Spurshot · February 8, 2016

Can you make it do it with the trans in manual and in the right gear for the acceleration? My first guess would be its the PCM/TCM looking for the right gear. My un modified tune will have a second or so delay when I punch it from say 30 mph, in drive. When I do the same thing with it in manual and select a gear that is correct for the hard acceleration first, there is no stumble. If this is the condition you're having, I think this is the price of having an automatic trans electronically tuned for economy

gilleydog · February 8, 2016

google sprintbooster ,have one for the last 2 years works great

davidio840 · February 8, 2016

I believe I know exactly what you are talking about. Mine has done this a few times especially coming out of a turn. You slow down, turn and then accelerate and there is a delay type situation. To me it seems like it is searching for the correct gears. I have actually taken mine to the dealership for this very reason and was given the "I can't duplicate the issue" excuse.

fondupot · February 8, 2016

Mine does it too. It's inconsistent tho.

Willshire · February 8, 2016

Mine does it at times too but then at about 4200 rpm it wakes right up. MAF or other ECM protection mode i suspect

Kerrslight · February 8, 2016

Had that exact same problem on a Toyota Avalon, turned out to be the MAF sensor. Cleaning the sensor would help, but replacing it about every 75K miles was the only true fix that would last about 50K miles.

Thats interesting. If something so simple could be the culprit I'll give that a shot.

Does it do it with traction control disabled?

It does it regardless of whether or not traction/stabilitrac is on or off.

Can you make it do it with the trans in manual and in the right gear for the acceleration? My first guess would be its the PCM/TCM looking for the right gear. My un modified tune will have a second or so delay when I punch it from say 30 mph, in drive. When I do the same thing with it in manual and select a gear that is correct for the hard acceleration first, there is no stumble. If this is the condition you're having, I think this is the price of having an automatic trans electronically tuned for economy

I haven't tried that. I'll try to do that on my way home today and see if I get any feedback. To be clear on my issue, happens the most when hard accelerating from a turn. Not flooring it, but just trying to get out of the hole. The truck gets up and goes for a second or two, then feels like it plateaus for half a second (I think around 2300RPM or so), then hard on it again. It isn't a feeling of searching for the right gear or lag in throttle response, but feels like an air or fuel issue. Those are just my observations.

FWIW, I do have a Diablew Performance Tune installed so factory tuning is gone and so is TM.

I believe I know exactly what you are talking about. Mine has done this a few times especially coming out of a turn. You slow down, turn and then accelerate and there is a delay type situation. To me it seems like it is searching for the correct gears. I have actually taken mine to the dealership for this very reason and was given the "I can't duplicate the issue" excuse.

Read the post right above this. I tried to explain it a little better. Does this sound like your same issue?

I know how it works at a dealership lol. I refuse to accept that answer. I will take them for a ride and duplicate the issue for them.

ic3man5 · February 9, 2016

It does it regardless of whether or not traction/stabilitrac is on or off.

Assuming you know you have to hold down the button for like 10 seconds for stabilitrak to disable and then it will reengage itself at 35MPH. A video of your dash when its doing this would probably help us out.

Kerrslight · February 9, 2016

Assuming you know you have to hold down the button for like 10 seconds for stabilitrak to disable and then it will reengage itself at 35MPH. A video of your dash when its doing this would probably help us out.

Yes I know how to turn stabilitrac off, as I stated it didnt make a difference whether it was on or off in my previous post. This is a simple acceleration issue. Neither TC or stabilitrac should be a factor in this as I am not accelerating hard enough to slip the tires. I will try to capture a video when I can.

oburgtiger · February 10, 2016

Same issue here. 2014 CC 5.3 4x4. It typically happens after a turn from stop. I make the turn at modest acceleration, then apply 3/4 throttle once straight like when pulling out into traffic. It can be kinda scary when you look in the rear view mirror and see that big rig barreling around the corner and your truck has decided that 35mph is all you're going to get.

The only way I've been able to overcome that when it happens is by flooring it. That leads me to believe its a tune issue between the trans and ECM. The truck always seems to be unsure of what gear to be in, especially at lower speeds.