Help Me Figure This Out

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Marc Marc

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2013 Yukon Denali Hybrid, 185K miles. Completely stock; no changes and well-maintained.

Recently I have noticed a change in my Yukon that I cannot decipher; and because I depend upon this car for frequent long trips, I hate to wait for failure to figure out what is wrong.

Unfortunately, the dealer and an independent mechanic have been making suggestions that to date have cost me several thousand dollars with no resolution of the problem.

To me the problem feels like a drive-train problem with the limited slip differential, but I could be wrong.

Background info: The problem is only noticeable when I first start out in the morning, and is never felt throughout the day, which is baffling to me.

I back into my paved driveway, which is inclined uphill to the street. Because the cul-de-sac is on an incline, with my driveway on a downslope, there is an 2-inch lip at the street edge of the driveway so water won't drain from the cul-de-sac into my driveway and home.

When I pull out of my driveway in the morning, and immediately turn Right in the cul-de-sac, at the point I turn right I experience what seems like a moment of slip in one wheel (guessing the passenger rear wheel) before the wheels lock up and drive normal. Obviously one wheel is turning less than the others, but this "slip" was never before noticeable.

At the end of the cul-de-sac there is a stop sign, and when I accelerate from the stop while turning Left, I again feel a moment of slip. After this second turn, it does not repeat even if I try to get it to repeat.

The sensation is also similar to a miss in the engine, and I began to wonder if this was the problem, but I just don't feel it is.

The dealer serviced the transmission, and no change. Then he serviced the rear differential and noted no problems, and no change. Then he told me it was my engine mount, which surprised me, but knowing how hard the engine lurches when switching from electric to gas while in traffic, I went along. I had an independent guy put in the drivers' front engine mount, and was told then the passenger front engine mount was also bad and needed to be replaced. Both mounts are now new, and the problem remains.

About three months ago I had my first brake job on the Hybrid (I am original owner and got 176K miles on the original brakes). This week a new caliper on the driver's rear wheel that was part of the brake job failed, and leaked brake fluid. I was thinking maybe this defective caliper was causing my "slip" feeling, like maybe the brake was sticking on one wheel in the mornings. Had the dealer replace this under warranty, and this repair fixed the brake problem, but not the "slip" as it still remains.

So what would you suggest might be the problem, and how could I check to verify the problem? All suggestions are welcome!
 

BG1988

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which surprised me, but knowing how hard the engine lurches when switching from electric to gas while in traffic, I went along.

AutoStop lag is caused by the AUX transmission pump.

A. the connectors are dirty
B. the pump is weak causing a delay
 
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Marc Marc

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Thanks for the suggestion. How do I test the AUX transmission pump?
 

BG1988

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Thanks for the suggestion. How do I test the AUX transmission pump?
does it jerk from when it resumes(automatic engine restart) while it's in motion?
the revise gear is powered by the electrical motor only the engine is only on to alert people that the suv is on... so it does have a lot of power by default 80hp/250ft.lb ish torque.


slip might be because of the surface I can make the tires sequel in a parking lot too easy.. the only time It slipped is when it was ICY we had like 10 inches of snow.. the Traction control kicked in... I was practically drifting while making a turn..

( Basically my back end was still going straight while the front end all ready made the turn)
Pretty much drifted that turn.

Try M4 see if it does it then
 
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Marc Marc

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Good idea; I will try that first thing out the driveway in the morning. Thanks for the suggestion.
 

BG1988

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Good idea; I will try that first thing out the driveway in the morning. Thanks for the suggestion.






Also service the Hybrid battery this is DIY repair super EASY (i'm trying to get some good karma here)

with 185k miles i'm sure it's well caked on" and never been serviced

Step 1 Remove any item from the rear cigarette lighter.(This is the most important step as not to damage the cig port) :)

Step 2 get damp cloth (NO dripping water )
OR vacuum

Step 3 Fold the seats all the way

Step 4 pop off the plastic cover for the battery

Step 5 open rear driver side passenger door

Step 6 remove dirt from intake of hybrid battery

Step 7 put cover back on Honestly, I removed mine for now (the summer to keep MAX air flow )



these are optional to verify the status of the of the fan(make sure it has no restriction)

put you hand near the grill you should be able to feel good suction..(the engine will need to be started)


if the "fan is loud" there is an issue with the exhaust cover gasket it should be almost 100% silent (the exhaust side makes the noise)


Don't touch the tiny hose


I'm going to home depo or lowes i'll see if i can find a cheap DIY fix for it



Mine just got plugged something in exhaust vent today(was able to flush it out) using the high speed exhaust setting on the unit
not sure how it got in there (maybe from the vent from under the SUV??)

possibly a squirrel ?


you can also go even further cleaning, the intake kick panel I removed mine (you will need a long flat head driver to remove the lower clips ) the seats will need to be in the up right position

you would not believe the amount of dust and garbage there.. also a free quarter..

nasty




20200715_235317.jpg 20200716_011645.jpg 20200716_013514.jpg
 
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Marc Marc

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Well, starting out in M4 didn't prevent the stutter.

The hybrid battery was replaced already just before the battery warranty expired. I will check the build-up of debris, but the car has been used in Southern California and debris is usually not an issue here.
 

BG1988

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Well, starting out in M4 didn't prevent the stutter.

The hybrid battery was replaced already just before the battery warranty expired. I will check the build-up of debris, but the car has been used in Southern California and debris is usually not an issue here.
does the shutter happen at about "9-11mph"?

it sounds like your having the slow speed shutter like i have

is your engine power limited (shift to M2 see if you can go above 3,000 rpm start at a lower speed DONT down shift to prevent damage or stall out)
with NO check engine, engine power limited message ?



trash behind the kick panel in the rear

i all ready cleaned it up good I cleaned the carpet with some foam spray i found at the 99 cent store I ended up going back and buying more bottles (sometimes they have good stuff and never get anymore in stock, so i always go back and get more just in case it happens)

took 2 cans to get it clean but worth it

Can't beat that a clean carpet for $2.20 :eek: :)

that is 99% off taking to a detailing shop they would charge at lest $200-300


20200716_163022.jpg 20200716_013258.jpg 20200716_013345.jpg
 
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Marc Marc

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The only time the shutter happens is when I first start out in the morning, coming from being parked. It really feels like the limited slip differential is locking up one wheel that may have been lagging behind.
 

BG1988

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The only time the shutter happens is when I first start out in the morning, coming from being parked. It really feels like the limited slip differential is locking up one wheel that may have been lagging behind.
yeah exactly the shutter is on a cold start for me as well

no reason for the diff to slip since i'm on flat land
 

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