Bionic

I have a 2010 Suburban 75th Diamond Edition with 140K miles.
Platform GMT931, Engine: 5.3 L (325 cu in) Vortec 5300 LMG flex fuel V8, Trans: 6-speed 6L80 automatic.

The problem I am having is that the car does not run smooth.

Here is a list of the symptoms that I am experiencing. The strange things is that there are no codes being thrown..

• In Park the car seems to idle rough. The idle hovers right above 500rpm, and moves up a little bit then down a little bit. Sometime I think I feel a stumble.
  
• When the car is in Drive but not moving the idle drops to 500rpm and I feel/hear a rumble/vibration/groan that is not present when the car is in Park. While in Drive does not idle perfectly at 500rpm, it will dip down slightly below 500rpm and recover to 500rpm sporadically.
  
• Sometimes the car will accelerate when braking. For example.. While driving, then braking to come to a stop, the car sometimes will surge while braking. When this happens I will need to apply more braking force to stop the car. It has scared my wife a few times when it does it to her.
  
• Sometimes the car will seem to power itself and accelerate on it's own. At around 1K to 1500rpm, at about 15 to 20mph the car sometimes will seem to power it self and maintain the speed as if I was giving the car gas... Sometime when starting the car the idle will seem a little high, and if I put the car in Drive, and release my foot of the brake, the car will start moving forward and and accelerate to about 5 to 8 mph...
  
• Sometime the car will briefly hesitate to accelerate from a stand still.
  
• Once recently, 2 yellow lights started flashing on the dash as if I were loosing traction.. I was accelerating from a stop sign at a regular pace, the car did not loose any traction or spin the tires but lights on the dash blinked at me as if I was spinning out or something. This happened at around 10 to 15mph... It only happened for a few seconds and went away. Like I said, this has only happened once, and I was in a construction zone where there was dirty and sand on the road. So maybe the rear did actually loose traction.. But I swear I didnt feel anything and did not jump on the gas.... IDK...
  
• Sometimes there seems to be a hard shift between 1st and 2nd gear. I usually will notice this when I am traveling while the engine is cold, and on residential streets. Where as I am having to do a lot low speed driving in 1st and 2nd gears due to having to stop at all the stop signs. It's like the car doesn't know when to shift to second, and down shift back to 1st..
  
• Sometimes when braking and right before the car stops,, at maybe 10 mph and the wait shifts I hear/feel a clank.
  
• My Gas Mileage on the Dash says 12.6 MPG (I know that really may not be useful info, but thought I would share.)

Here is a list of recent things that I have had done trying to fix the issues I listed above..

• I have replaced all 3 motor mounts with OEM mounts
  
• New acdelco plugs and wires.
  
• Throttle body cleaned and fuel injectors serviced by the dealer.

Car still has the issues I listed.

The dealer and the mechanics I talk to seem to be lost since the car does not throw any codes.

Are there any tests I can request to be done that might point me in the right direction?

I have seen people mention on various forums about potential fixes... vacuum leak, idle relearn, ecm reprogram, replace the throttle body, replace the MAF, rebuild the engine due to AFM issues, etc..

I am located in the Dallas Fort Worth Metroplex, is there a mechanic or shop that is recommended to hunt down and repair these types of issues?

PNW NBS Z71

This little jewel right here could be the problem. https://www.rockauto.com/en/moreinfo...002726&jsn=901

Other info supplied about what causes this to go bad and what you may experience: I know you said no codes but maybe with no codes there is still a problem with this. My first guess was the throttle bore cleaning. You may also have a dirty MAF sensor and needs cleaned. Cleaner and instructions are at a parts store that sells the cleaner made especially for the MAF sensor. Sometimes it is bad enough that the MAF has to be replaced.Throttle Position Sensor (TPS) Failure:
TPS sensors often fail due to high heat under the hood and constant contact from the wiper arm.

Signs of Failure:

• Check Engine Light with codes ranging from P0120 through P0125
• Engine hesitation when accelerating
• Rough Idle

Bionic

What test could I have done that will plot the readings of the MAF and TPS?

If I go to a dealership and have them do a diagnostic is there a certain type of diagnostic I should ask for? Will they give me graph printout that show the output of those sensors so that we can see exactly what is being output by those sensors? Are dealers the only people that have these special computers that can read individual sensors?

Here is document I found talking about testing the MAF and the TPS sensors..
https://support.alldata.com/sites/ma...ing_110918.pdf

Do you think this test ran on my car would be worth it?

Also what what type of Vacuum test should be ran to check if there is a vacuum leak causing these issues?

When I ask the service advisor at the dealer about running various test, they feel as if the tests will not come back and show anything because if the sensors where bad they would throw a code.

Bionic

Here is document I found talking about testing the MAF and the TPS sensors..

https://support.alldata.com/sites/ma...ing_110918.pdf

I just ordered the . It says it will be delivered today by 6pm.

For my vehicle the supports live data & graphing for the following.

• Fuel system status
• Calculated LOAD Value
• Engine Coolant Temperature
• Short Term Fuel Trim - Bank 1 / Bank 3
• Long Term Fuel Trim - Bank 1 / Bank 3
• Short Term Fuel Trim - Bank 2 / Bank 4
• Long Term Fuel Trim - Bank 2 / Bank 4
• Fuel Rail Pressure (gauge)
• Intake Manifold Absolute Pressure
• Engine RPM
• Vehicle Speed Sensor
• Ignition Timing Advance for #1 Cylinder
• Intake Air Temperature
• Air Flow Rate from Mass Air Flow Sensor
• Absolute Throttle Position
• Bank 1 - Sensor 1
• Bank 1 - Sensor 2
• Bank 2 - Sensor 1 / Bank 3 - Sensor 1
• Bank 2 - Sensor 2 / Bank 3 - Sensor 2
• Time Since Engine Start
• Distance Traveled While MIL is Activated
• Commanded Evaporative Purge
• Fuel Level Input
• Number of warm-ups since DTCs cleared
• Distance traveled since DTCs cleared
• Evap System Vapor Pressure
• Barometric Pressure
• Catalyst Temperature Bank 1, Sensor 1
• Catalyst Temperature Bank 2, Sensor 1
• Control module voltage
• Absolute Load Value
• Fuel/Air Commanded Equivalence Ratio
• Relative Throttle Position
• Ambient air temperature
• Absolute Throttle Position B
• Accelerator Pedal Position D
• Accelerator Pedal Position E
• Commanded Throttle Actuator Control
• Alcohol Fuel Percentage

So out of that list, what all should I graph that may lead to figuring out what is going on with my car?

Thanks!