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Torque Converter

Two-fold question
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Torque Converter

Postby starspangled6.0 [OP] » Dec 19 2011, 3:07am

This question has two parts:

1. Under what circumstances does the torque converter normally lock up in the 4L80E?

2. I took a little road trip today (about 75 miles), and noticed something funny happening to my transmission. On the way back, the torque converter didn't lock up until after about 20 minutes of cruising at 60 MPH on the freeway. After this, it stayed locked until I took the cruise off; when I put the cruise back on, it would only lock up again after the transmission temp touched 150. When the converter was locked, the temps would dip to about 125-135 (outside temps were about 45*F). Engine temp was normal; I was at 60 for nearly the entire trip, both ways. MPG numbers were great; they were just a little higher when the converter would lock. However, the RPM would go up 200-300 if it was unlocked.
On the way up, it didn't lock until we had been on the road for about 15 minutes, but this was from a cold start, at 25*F. Even more strange, also on the way down, I had to pass some cars, so I popped up to 65-70 MPH, with the converter unlocked. I stayed there for about a minute, with the RPM holding at 2500. Then the check engine light started flashing, and I dropped back down to 60 MPH. The light stopped flashing shortly thereafter. When I hit traffic, and had to stop using cruise control, it would lock up right away. What gives? Is this somehow normal operation? The only modifications I've done to the transmission are flushing it completely and filling it with AMSOIL Fuel Efficient synthetic ATF, and it's also got the Hypertech programmer, which does change the way the transmission behaves (but not too drastically). It's got the stock 4.10 axle ratio, and stock tire size. I'm pretty sure it has done this since I purchased it, but since I'm becoming more and more an anal truck owner, I'm starting to notice this things. Any ideas are helpful...
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Re: Torque Converter

Postby ASTE25 » Dec 19 2011, 6:00am

I would suggest seeing if you have any codes in the system. You could have a solenoid malfunctioning. Hard to really say what the problem is. Try starting with getting the system checked for codes.
Jordan
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Warn 9.5 TI winch and a Warn Trans4mer brush guard
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Re: Torque Converter

Postby starspangled6.0 [OP] » Dec 19 2011, 4:24pm

I haven't experienced any other issues... driving around town, it works great.
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Re: Torque Converter

Postby starspangled6.0 [OP] » Dec 19 2011, 7:07pm

Checked today for any codes. Scanner showed 0 codes.
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Re: Torque Converter

Postby ASTE25 » Dec 20 2011, 2:16am

Hard to say. It may be a mechanical type problem within the transmission (like a seal leaking or a worn clutch pack).
Jordan
2005 Victory Red Silverado Z-71 4X4 regular cab
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Warn 9.5 TI winch and a Warn Trans4mer brush guard
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Re: Torque Converter

Postby jack101789 » Dec 20 2011, 3:06am

my 2008 silverado 4.8L V8 wont shift into 2nd......what causes that to happen...
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Re: Torque Converter

Postby starspangled6.0 [OP] » Dec 20 2011, 5:13am

Thanks for the input, Jordan. I did a lot of freeway time again tonight, and didn't have a single issue. I don't know why it has acted up twice on that single stretch of road, but I'll try not to worry about it.
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Re: Torque Converter

Postby ASTE25 » Dec 20 2011, 5:36am

jack101789 wrote:my 2008 silverado 4.8L V8 wont shit into 2nd......what causes that to happen...

It could be a lot of things. Anything from a bad solenoid to a worn out clutch pack.
Jordan
2005 Victory Red Silverado Z-71 4X4 regular cab
5.3 / 4L60E
Warn 9.5 TI winch and a Warn Trans4mer brush guard
User avatar
ASTE25
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Shifting into Sixth Gear! [L3]
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Posts: 3329
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Joined: Jan 03 2011, 6:37am
Years of membership: 1 year of membership
Location: New Market, Alabama
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Re: Torque Converter

Postby starspangled6.0 [OP] » Jan 12 2012, 3:53pm

Update:

I drove the truck on the freeway with the programmer off. Sure enough, the moment I hit cruise going 65 MPH, the converter locked up right away. I hope Hypertech will have some answers :x!
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starspangled6.0
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Shifting into Sixth Gear! [L3]
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Posts: 3483
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Images: 42
Blogs: 24
Joined: Nov 08 2010, 9:38pm
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Year: 2003
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Extra Info: 2500HD 6.0L 4X4 SLT
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Re: Torque Converter

Postby ASTE25 » Jan 12 2012, 9:40pm

I didn't know you had a tuner. It does sound like it may be a tuner setting issue.
Jordan
2005 Victory Red Silverado Z-71 4X4 regular cab
5.3 / 4L60E
Warn 9.5 TI winch and a Warn Trans4mer brush guard
User avatar
ASTE25
Automotive Technician
Automotive Technician
Shifting into Sixth Gear! [L3]
Shifting into Sixth Gear! [L3]
Posts: 3329
Topics: 5
Images: 12
Blogs: 0
Joined: Jan 03 2011, 6:37am
Years of membership: 1 year of membership
Location: New Market, Alabama
Year: 2005
Make/Model: Chevrolet Silverado
Extra Info: Regular cab Z71 4X4
Group Membership:
Automotive Technicians
Registered users
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