2011 Chevy Tahoe “Tug issues”

[NickTransmissions]

I had the spark plugs replaced by my mechanic. Fluids replaced including the transmission . Chevy took a look at it and replaced a part and found wires were touching and overheating in the engine. My mechanic and Chevy mechanics are competent and I feet it’s something internal. My guess its AFM issues which could lead into other areas. My first guess was transmission. Not a mechanic but I’ve felt this before over 30 years of driving.

I tried buying a scanner but the purchase on line fell through. Do you have any make and model scanner you recommend. Place to purchase that does live scanning/analysis?

Thank you

Very helpful.

Ken

Most Snap on scan tools will display live data as will a GM TECH2 (TECH2s will work on any vehicle up to 2013). I have bought and sold scan tools off eBay and online forums like this one.

The main thing is to confirm exactly when your symptom is happening and if it's consistently happening at that same point (ie same vehicle speed) or if it's happening more or less at random. Based in the info you provided, it seems to be happening only around 20mph or so. I would think it was engine-related, it would be more random/distributed relative to road speeds.

Please quote my post or mention me if you have any additional questions/need more info as that's the only time I get notified.

You can also take a look at my 6L80 thread on here as well as youtube channel for more transmission-specific info (see links in my signature).

 

[donjetman]

I tried buying a scanner but the purchase on line fell through. Do you have any make and model scanner you recommend. Place to purchase that does live scanning/analysis?

Thank you

Very helpful.

Ken

 

[The Grey Beast]

Hi to all.

So I went to the Chevy Dealer and drove in for a code read. Nice manager named Ed. So he attached the tool and found that the code for the break extension was coding. Which is true as we have discussed it’s not working. Long story short there is nothing coding for the slipping that I’ve been feeling. So it’s most likely the transmission. Ed did pull the vehicle in the shop and had the tech check the transmission fluid. It’s clean however the tech did say the it’s one quart to high. Tech told him this can course problems.So I send the vehicle in on the 17th to be checked out.

I’m insured in case the transmission fails but what’s interesting is the dealer sends codes to the insurance company. But a bad transmission won’t code. So the insurance company needs more that just “Heyit’s not working properly.” So I’m trying to work out the kinks.

Thank you to all.

Ken

 

[NickTransmissions]

Hi to all.

So I went to the Chevy Dealer and drove in for a code read. Nice manager named Ed. So he attached the tool and found that the code for the break extension was coding. Which is true as we have discussed it’s not working. Long story short there is nothing coding for the slipping that I’ve been feeling. So it’s most likely the transmission. Ed did pull the vehicle in the shop and had the tech check the transmission fluid. It’s clean however the tech did say the it’s one quart to high. Tech told him this can course problems.So I send the vehicle in on the 17th to be checked out.

I’m insured in case the transmission fails but what’s interesting is the dealer sends codes to the insurance company. But a bad transmission won’t code. So the insurance company needs more that just “Heyit’s not working properly.” So I’m trying to work out the kinks.

Thank you to all.

Ken

Did they drop the pan or just check the dipstick?

One quart too full shouldnt cause issues however anytime you overfill the engine or trans, the oil (or trans fluid) will begin to foam thus causing functional issues inside the engine or transmission. If you overfill the trans, the excess should be exhausting out of the vent tube on top of the unit. If that passage is clogged somehow no venting takes place.

Did you see any fluid venting from the top?

And a bad transmission will "code" more often than not but sometimes they dont. Internal case issues usually show up as either solenoid performance codes or gear ratio error codes..

 

[The Grey Beast]

Hey thank you.

So they checked the dip stick not the pan. Didn’t know transmissions could code. Well it didn’t. But I’ve noted your response. so your initial diagnosis was the engine. Not the transmission. Do you recommend a transmission flush any way to be sure? It’s 150 thousand miles on the Tahoe. Can a Transmission flush cause problems for an older transmission? I have no way of knowing if the previous owners had the transmission worked on or replaced it.
I will say that the slipping has stoped. It slips slightly but no way near the stop and go ride home a few days back.

 

[NickTransmissions]

Hey thank you.

So they checked the dip stick not the pan. Didn’t know transmissions could code. Well it didn’t. But I’ve noted your response. so your initial diagnosis was the engine. Not the transmission. Do you recommend a transmission flush any way to be sure? It’s 150 thousand miles on the Tahoe. Can a Transmission flush cause problems for an older transmission? I have no way of knowing if the previous owners had the transmission worked on or replaced it.
I will say that the slipping has stoped. It slips slightly but no way near the stop and go ride home a few days back.

Are you responding to me specifically? If so, please quote my posts so I get notified. I just happened to take one more look at this thread before I went to do something else and noticed you had replied.

My initial diagnosis was NOT the engine; it was the transmission.

Read the second line from post #9 (screen shot for your quick reference).



Doing a flush is your call...Many subscribe to the belief that it causes more problems than it solves but my take is that those problems were already there and the flush made no difference. That said if your fluid has already been changed recently, I wouldn't bother as the cost/benefit is marginal at best. If not, I'd go ahead and do it plus a filter as a partially clogged filter can also cause your symptoms though they would appear at all points on the shift curve especially when shifting under heavier acceleration/higher RPMs as opposed to only low speeds.

If it's still slipping, there's definitely a problem but it just hasn't become big enough yet to either throw codes (again, sometimes they do, sometimes they don't) or manifest in a way that it's unmistakable that the trans is failing.

150k is when they commonly start to go.

 

[The Grey Beast]

Sorry I re read the thread and yes you pointed to the transmission.

I tried posting earlier hope I didn’t have an incomplete post. Anyway the Tahoe runs fine but it was bad driving back to Sacramento ca. thought the Tahoe may fail while driving back home . It’s runs ok now and although it’s slips it’s a slight one. I’m going to let the dealer drain a quart of the transmission fluid and see what that does. I’ll add some of the you said and see what they say. I feel if we explore to much we’re taking money and it could make it worse.

Thank so
Much

Ken

 

[Gearz]

You say a tug or jerking. This could be engine related, for example. Lazy oxygen sensors before cat converts. MAF sensor that is dirty, throttle body extremely dirty. You also said it got better after fueling, evap canister full-of fuel,vent valve and purge solenoid. All these thing are very hard to diagnose without scan tools. These trucks are also known for ground issues that can cause problems. Do you have a Range tech that disables 4 cylinder mode because if you don’t you need one.

 

[Matthew Jeschke]

My first assumption was the same as @NickTransmissions transmission isn't locking up after gear shift. Closely monitor your fluid and transmission temp if you have gauge for that. Heat kills transmissions.

In my opinion, what happens over time, is the valve body wears out especially if fluid isn't well maintained. If you do a flush could in theory clog the valve body as debris get's loose in it. However, dirty fluid will also prematurely wear out a transmission so pick your poison. If your fluid is clean, there's no need for a flush though.

I recommend, drain a quart of fluid, you can suck it out through the transmission dipstick tool with a pump. Then add 1 quart of Lucas Transmission Fix / Stop Slip. This fluid is designed to address the specific issue of a worn valve body. You can add up to 2 quarts but start with a quart and see if it gets better. It won't hurt anything either way. If it helps then I'd suspect the valve body is a little warn. You can keep driving it and or replace the valve body.

I suspect personally a LOT of transmission issues originate at the valve body. The gears don't lock up immediately, transmission overheats, and destroys the clutches. If you catch it quick enough, you can replace the valve body. Most shops don't want to do that but it can be done w/o dropping the transmission. It's a fairly simple job.

It's possible it's something else, however, the most catastrophic thing would be your transmission so you want to make sure that's good as per above, possibly more. I'm not as familiar with your control system / PCM. they changed them up sometime after the vehicles I have. You computer is a torque management based computer instead of airflow management. I think I have the terminology correct. Anyways, an issue with say a throttle body can cause hesitation as well as multiple other sensors because computer reads a desired torque (gas pedal) then commands that through TAC throttle actuator control, then reads various sensors to see if output torque is desired amount as well as a safe amount.

 

[NickTransmissions]

I suspect personally a LOT of transmission issues originate at the valve body. The gears don't lock up immediately, transmission overheats, and destroys the clutches. If you catch it quick enough, you can replace the valve body. Most shops don't want to do that but it can be done w/o dropping the transmission. It's a fairly simple job.

This is true for most, particularly the 6L transmissions. TCC failure often has its roots in the valve body (tcc regulator valve) or pump (tcc control or limit valves worn).

Bumpy, jerky shifts are often the compensator feed regulator valve, esp if they happen in all or most gear changes. Late harsh shifts are often the individual clutch regulator valves and often times, its wear in one or more of those valves that triggers solenoid performance / stuck DTCs. AFL valve weakness will lead ti eventual slipping due to insufficient apply circuit fluid pressure available to the line/clutch pressure solenoids (all transmissions).

Sonnax zip kit or Transgo reprogramming kit should be installed into every one on overhaul and that's after the valve body is thoroughly tested on the Sonnax vacuum tester to ensure it's worth overhauling vs buying a new one.