2007 GMC Denali stalls after towing

[syclnjr]

It doesn’t make sense to me either but the possible heat point could be from the exhaust as well. Still haven’t jacked it up to look at what I want to do for the sleeve.
It’s a cheap thing to try if it fixes it great

 

[vettes980]

It’s a sticking torque converter. When’s the last time the fluid was changed? If you don’t know, then change it, and add a bottle of shudder stop tranny additive. I chased this problem, threw basically everything at it until I found out what it was. Mine would also stall after long trips and then got where it would stall after shorter trips. Last resort took it to a tranny shop and he gave me a bottle of additive and it never stalled for months. Finally did after a 3.5 hour drive so I took my ass under it and wrestled the fluid out of it and added another bottle of additive and no more stalling. Pro this time kicking the can on the issue but I’ve put about 2500 miles on it and one trip to Michigan with out issues.


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[syclnjr]

It’s a sticking torque converter. When’s the last time the fluid was changed? If you don’t know, then change it, and add a bottle of shudder stop tranny additive. I chased this problem, threw basically everything at it until I found out what it was. Mine would also stall after long trips and then got where it would stall after shorter trips. Last resort took it to a tranny shop and he gave me a bottle of additive and it never stalled for months. Finally did after a 3.5 hour drive so I took my ass under it and wrestled the fluid out of it and added another bottle of additive and no more stalling. Pro this time kicking the can on the issue but I’ve put about 2500 miles on it and one trip to Michigan with out issues.


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Thank you for this insight on it. One thing that I don’t think that I mentioned is part of what I was going to do is change the fluid, it isn’t very old, or at least didn’t have many miles on it since the last change but I wanted to anyway as a valid step and especially before I put in the new trans cooler.

I do have this additive for the trans, Life Automotive Products Transmission Smart Blend Additive Red Synthetic ATF Protectant, as a recommendation from a long time friend that builds transmissions.

Quick question for you on yours and what I hadn’t seen in this thread about the issue, when yours would die when you came to a stop, could you get it to start by putting the throttle on the floor and cranking? Trying to understand if a locked up TCC would cause a lack of firing for a long period of time or if you just mashed the gas and got it to fire up.

Thanks

Mike

 

[vettes980]

Thank you for this insight on it. One thing that I don’t think that I mentioned is part of what I was going to do is change the fluid, it isn’t very old, or at least didn’t have many miles on it since the last change but I wanted to anyway as a valid step and especially before I put in the new trans cooler.

I do have this additive for the trans, Life Automotive Products Transmission Smart Blend Additive Red Synthetic ATF Protectant, as a recommendation from a long time friend that builds transmissions.

Quick question for you on yours and what I hadn’t seen in this thread about the issue, when yours would die when you came to a stop, could you get it to start by putting the throttle on the floor and cranking? Trying to understand if a locked up TCC would cause a lack of firing for a long period of time or if you just mashed the gas and got it to fire up.

Thanks

Mike

Yes, hold the pedal down and crank. Sometimes it would take 5 seconds, sometimes up to 15 seconds to fire.


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[jz57]

I am 2nd one after vettes980, the symptom in this thread is mostly related to transmission shift, stuck torque converter solenoid or other speed shift solenoid, except "N".

The following solution may apply:

1) Install an external auxiliary transmission cooler
2) Drop transmission pan, replace filter and ATF fluid with synthetic one.
3) Add ATF modification, like vettes980 did, or use Lube Guard ATF Protectant
4) Expensive venue, drop the pan and replace solenoids
5) Drive like manual stick, shift into "3" gear before stop, manually force releasing solenoid.

The similar issue happened among 2009 Dodge/Chrysler minivan, the engine stalled after getting off hi-way and at stoplights. There was a TSB issued to replace solenoid pack.

Similar symptom threads:

2007 Denali hot stall:

https://www.tahoeyukonforum.com/threads/07-denali-hot-stall.26430/page-3

2007 GMC Denali stalls after towing:

https://www.tahoeyukonforum.com/threads/2007-gmc-denali-stalls-after-towing.73312/

Stalled out:

https://www.tahoeyukonforum.com/threads/stalled-out.117045/

It’s a sticking torque converter. When’s the last time the fluid was changed? If you don’t know, then change it, and add a bottle of shudder stop tranny additive. I chased this problem, threw basically everything at it until I found out what it was. Mine would also stall after long trips and then got where it would stall after shorter trips. Last resort took it to a tranny shop and he gave me a bottle of additive and it never stalled for months. Finally did after a 3.5 hour drive so I took my ass under it and wrestled the fluid out of it and added another bottle of additive and no more stalling. Pro this time kicking the can on the issue but I’ve put about 2500 miles on it and one trip to Michigan with out issues.


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[syclnjr]

jz57 ,

Thanks for this. I had found something early on that it was the solenoid pack in the trans sticking, but didn't want to believe it with the lack of engine start after it happened

As noted, fluid, filter, new cooler, additive, etc will be done and see how it rolls out.

Thanks

Mike

 

[jz57]

Hi, Mike,

Please post back and looking forward to see the out coming.

After do pan dropping and fluid/filter replacing, do a fluid flushing, replace all the fluid inside torque converter. Is is an easy job, disconnect transmission fluid return line on passenger-side upper radiator, run the engine and keep fill the fluid. There is an article in this forum about the job. Do a search.

 

[08grey]

Hi, Mike,

Please post back and looking forward to see the out coming.

After do pan dropping and fluid/filter replacing, do a fluid flushing, replace all the fluid inside torque converter. Is is an easy job, disconnect transmission fluid return line on passenger-side upper radiator, run the engine and keep fill the fluid. There is an article in this forum about the job. Do a search.

Any update here?

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[oldtimer]

2007 Yukon XL Denali, 6.2L, 180,000 miles.

Is there a list of "Events" (coolant temp, low oil pressure, etc.) that would tell the ECM to stop engine?

I am chasing this issue, have replaced camshaft & crankshaft sensors, alternator, added heat tape to fuel rails, replaced oil pressure sensor, purge valve, & gas cap, and fuel pump, spread over 4 years. Purge valve & gas cap were only CEL issues.

Will die if in drive or tow haul mode.
Only seems to happen if trans temp is above 198, won't restart till trans temp drops to 174.
Coolant temp is 210 to 220ish (hate gage that is marked 160 - 210 - 260).
Ambient is above 85.
Transmission is 5 years old, and has 84,000 miles on it, installed by GMC dealer.

 

[HD_LS]

2007 Yukon XL Denali, 6.2L, 180,000 miles.

Is there a list of "Events" (coolant temp, low oil pressure, etc.) that would tell the ECM to stop engine?

I am chasing this issue, have replaced camshaft & crankshaft sensors, alternator, added heat tape to fuel rails, replaced oil pressure sensor, purge valve, & gas cap, and fuel pump, spread over 4 years. Purge valve & gas cap were only CEL issues.

Will die if in drive or tow haul mode.
Only seems to happen if trans temp is above 198, won't restart till trans temp drops to 174.
Coolant temp is 210 to 220ish (hate gage that is marked 160 - 210 - 260).
Ambient is above 85.
Transmission is 5 years old, and has 84,000 miles on it, installed by GMC dealer.

While its been few months since this post, this information may help others with this problem. While sensors, transmission, etc. can cause this; perhaps the most common cause of this (hot stall at low speeds & idle, no start when hot) has been identified and solved elsewhere. Specifically as it applies to 2007-2008 6.2L L92 engines, but it may apply to others as well.

This is a very common problem on 07-08 6.2L engines: The problem is related to a combination of low hot oil pressure at low engine speeds, and the cam phasor. The ECM commands the cam phasor to exteme angles at highway cruise engine rpms, to get a small fuel economy increase. The commanded cam angle is so extreme, that the engine would die at idle and/or not start if it were to stay stuck at that extreme angle. You can see where this is going. Low hot oil pressure, prevents the cam phasor from going back from the highway fuel economy phase angle to an angle suitable for low rpm and idle operation. The engine then stalls exactly as described, and may not restart for quite some time. While low hot oil pressure can be caused by oil pump pickup tube O-rings, etc ... in 2007-2008 6.2's are known for cam bearing wear issues that cause low hot oil pressure.

First, check your hot oil pressure. Remember that oil temperature takes longer to heat up than engine coolant temp, and towing will get it hotter still. Less than 20psi at hot idle could be a problem for the cam phasor operation.

So what can you do about it? One element is to increase your hot oil pressure: Switch to an oil that has excellent viscosity and film strength at high temperatures (for example Amsoil Signature series 5W-50), and keeping your engine as cool as possible. The second element is to find a tuning shop, with HP tuners, that can program the Cam phasor to stay at a fixed angle, so it never gets out of whack in the first place. This can be a good solution, because the oil pressure may be too low to actuate the cam phasor, but still high enough to operate the rest of the engine reliably. While I haven't had the problem, I'm doing the first part of this as a preventative measure.