2011 Tahoe sputters under low RPM

[divetime1972]

I have a 2011 Tahoe and about 2 months ago it started shuddering or sputtering when at low pm and under load.

It happens at low rpm when trying to accelerate easy. If I hit the gas harder, it won't do it. But if I try to accelerate gently, it will jerk / shudder. Happens from about 1000 rpm (my normal idle) up through about 2000 rpm. after I reach that higher rpm, everything's perfect. It happens in every gear...even at highway speed, as long as the car has shifted into the next gear and the rpms settle down low, if I accelerate easy it will do it. The problem is more significant the higher the load...as in going up a hill.

No error lights on the dash. Took it in to the shop; no codes. Their best guess was to clean the throttle body - no help. They did check the fuel pressure and said it was about 5 psi low, but said that wasn't enough to make a big enough difference to put in a new one...yet.

Any thoughts?

Thanks...and if you reply, I'm not a mechanic...not even close, so in english!

 

[metelhead]

when was the last spark wires and plugs changed?

>>>For some reason these motors are quite picky on plug wires and plugs....at least thats been my experience.....9/10 anytime I've had low rpm issues this has been the fix.

 

[divetime1972]

Never yet...I'm at 45K miles.

I mentioned that to the shop - they seemed fairly dismissive that was the problem.

 

[kbuskill]

If your truck is idling at 1000rpms then I'm guessing something is wrong.... It should idle around 600rpm when warmed up.

 

[divetime1972]

Meant 500 rpm...was just visualizing the first mark on the tach...500. Dealer cleaned the throttle body and reset the idle to try and fix...didn't work.

 

[StockHoe]

I have a 2011 Tahoe and about 2 months ago it started shuddering or sputtering when at low pm and under load.

It happens at low rpm when trying to accelerate easy. If I hit the gas harder, it won't do it. But if I try to accelerate gently, it will jerk / shudder. Happens from about 1000 rpm (my normal idle) up through about 2000 rpm. after I reach that higher rpm, everything's perfect. It happens in every gear...even at highway speed, as long as the car has shifted into the next gear and the rpms settle down low, if I accelerate easy it will do it. The problem is more significant the higher the load...as in going up a hill.

No error lights on the dash. Took it in to the shop; no codes. Their best guess was to clean the throttle body - no help. They did check the fuel pressure and said it was about 5 psi low, but said that wasn't enough to make a big enough difference to put in a new one...yet.

Any thoughts?

Thanks...and if you reply, I'm not a mechanic...not even close, so in english!

Click the button on your dash that shows if your in V8 or V4 mode. Next time it happens, look to see which mode this is happening in and let us know. It's probably happening while in V4 because you stated that if you step on the gas peddle slowly it still happens. This is because most likely your still in V4 but if you step on the gas faster, your truck goes right into V8 mode. This happened to mine as well and once I turned off the AFM, all was fine.

 

[TheLoveClaw]

I have been experiencing this same thing the past couple of months. I was actually talking about it on another forum in here last week.

I don't drive the Yukon as much as my wife but was just thinking today that I should check to see what mode it's running in. I have been wanting to buy a Diablo Sport Tuner for it for some time now but don't want to spend the money until I figure this out. I have Torque Pro and have set it up to monitor fuel pressure, and misfires. Just added some more to the dashboard today to see if anything pops out at me. So far everything is normal. When I took it to the dealer they said it was tires that was causing it. $860 later for tires and an alignment and it's still doing it. Was running the AC over the weekend and it seemed to make it worse which is why I was thinking fuel pressure, but the V4 mode sounds more probable. I've been wanting to turn that off since we got it. I go through an extra quart of oil per oil change.

Another thought that may throw you deeper down the rabbit hole.... A couple weekends ago we went to Cave of the Winds, and the driveway to it is very steep and windy. We were going slow and everyone in the truck could feel it bucking. I'm very confident that it was not in V4 mode then because of the grade. It felt like the engine was working plenty hard but nothing was making it to the road.

It's camping season so I have to get it figured out. I'll let you know once I do so hopefully it can save you some time and money.

 

[TheLoveClaw]

We went for a quick ride last night (plenty long for the vehicle to warm up), and I only noticed the issue in V4 mode. I only noticed it once and my wife said she couldn't notice it at all. Nothing on Torque Pro jumped out other than the 02 sensor charts. Bank 1 Sensor 1 was different than Bank 2 Sensor 1. Bank 1 was more of a peaks and valleys and Bank 2 looked more like plateaus. I'm not really a mechanic, so I don't know how to interpret that.

 

[DStarr02]

Start your truck during the darkest part of the night turn off all your lighting and check under the hood look over the plug wires for a blue light coming off the wires, it could be as small as a pin hole in the wire. I had almost the same feeling for the throttle on my better i had.

 

[TheLoveClaw]

I had though of that as the first troubleshooting. The vehicle had 85k miles so I replaced the plugs and wires. Went oem on the plugs and magnacore on the wires.

Using Torque Pro on misfires I get a whole bunch of 0's for current and history. Would the arcing show for a bad coil pack?