2012 Chevy Equinox surge/ lacks power- no mil

Greg Owner Auburn, Washington Posted   Latest  
Question
Driveability
2012 Chevrolet Equinox LT 3.0L (5 LFW Flex) 6-spd (6T45)—2GNFLGE55C6382978
Surge
Hestitation
Lack of Power

Good morning to all- 1st time poster here. Our cashier started complaining of a lack of power getting up to freeway speeds. we couldn't feel it at first but it has developed into a significant lack of power when attempting to accelerate. it is now to the point if you hold the engine speed at about 1600 rpm in neutral you would swear it was misfiring enough to set a fault but it does not. freewheeling like that it almost feels like EGR on an old 4.3 pick up. If you tip the throttle slightly like you want to gain 5 mph on the freeway you can actually feel it start to hesitate/ hold back. so here is the weird part- NOTHING is showing up. We had cleaned carbon about 5 k back when we did plugs for regular maintenance. No vacuum leaks/ exhaust leaks- smoked it from tail pipe to air filter housing- nothing. fuel trims fluctuate a bit but stay mostly around zero. all variable cam timing systems working normally. no timing chain stretch. map sensor and mass air flow sensor data normal- however we did try an AC/DELCO map and mass just to be sure the data we saw was right- no change. new spark plugs 5 k ago- she had two coils failing and opted for all because of intake configuration. Per a GM drivability technician at the dealer we checked fuel tank vent valve- it is not leaking air into plenum. Adding fuel at 1600 rpm does not seem to improve rough run condition. Fuel pressure is spot on. Cleaned throttle body and reset idle. vehicle was purchased about a year ago at 95k- no history on fuel used. Has had top tier fuel for last 10k. All other data looks perfectly normal except for the random and slight variations in fuel trim while driving and when you aggravate the condition fuel trims do not change. I am leaning towards wanting to have fuel injectors tested but I don't completely trust that tests/ cleaning on the new style injectors helps. Any ideas group? Thanks in advance from Jenny and our technicians! Greg H

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Eric Owner/Technician
Edgerton, Wisconsin
Eric
 

What testing have you done? Please post actual test results of those tests. Have you checked exhaust back pressure?

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Greg Owner
Auburn, Washington
Greg
 

Thanks Eric, have not done back pressure only because once full throttle is applied and fuel enrichment kicks in it takes off. will do today​.​will post info requested soon. thank you all for your patience as i am posting for a tech off today and gathering data from out team as you asked. We are grateful! will post data soon

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Greg Owner
Auburn, Washington
Greg
 

ERIC WE GOT SLAMMED AND HAD TO PUT THIS TO THE SIDE. I HAVE NOT FORGOTTEN YOUR REQUEST AND AM GRATEFUL FOR YOU HELP SIR. WILL POST CURRENT DATA ASAP​.​GREG H

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Albin Diagnostician
Leavenworth, Washington
Albin
   

start your testing here diag​.​net/msg/m61bqk58h6…

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Geoff Diagnostician
Lahaina, Hawaii
Geoff
 

Test back pressure. Like Eric said.

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Jim Owner/Technician
Charlotte, North Carolina
Jim
 

This sure smells like a timing chain - are you 100% sure that chain/ valve timing is good? How did you verify timing chain stretch?

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Greg Owner
Auburn, Washington
Greg
 

THANKS JIM WILL DOUBLE CHECK AS WE THOUGHT SO TOO. WE USE THE AUTEL AND SNAP ON SCANNERS- I DID NOT SEE DATA ON STRETCH (PHASE)- SOMEONE SAID WE SHOULD SEE IT IN DATA STREAM BUT NO LUCK WITH OUR TOOLS- AM I BEING STUPID HERE? ALSO WE GOT BUSY AND HAD TO PUSH THIS OFF TO THE SIDE- I WILL POST REQUESTED INFO AS SOON AS I CAN. AS I MENTIONED- POSTING FOR DAVID AS A SERVICE ADVISER SO STUPID STUFF

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