LB7: Loping and shaking at idle/NO throttle response

Austinflb7

New member
Aug 24, 2017
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I have a 2002 lb7 with 170,000 miles on it. During college I leave my truck at home and it is lucky to get driven once in two to three weeks. The batteries have died probably about three times now and this time after jumping the truck I started it up and it sounded like a hard start at first. It continued to lope and did not change after five minutes. Tried to press the pedal a little to see if it would pick up and the throttle has no effect at all. A "reduced engine power" message came on the message center. Put two new batteries in and did not fix anything. Did not know if it could just be a low voltage issue. Engine shakes bad and sounds like its not running with all cylinders. This is the first time I've started it in three weeks and it ran just fine at that time. What could be the problem? All help is appreciated.

Update:Scanned the truck and got the codes P0380 and P1635. Also found some chewed wires along with some walnuts on the back of a connection that looks like it leads to a sensor. No clue what this sensor is but I have some pictures along with the same connection on an older lb7 of mine so that there is a better view.
 

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tsd_billy

Member
Apr 5, 2016
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oklahoma city
Need to see codes to give you a proper solution to the problem otherwise its just pissing out a window lol. Get your tuner on it and read codes. Im assuming you have something in it idk anyone with a bone stock lb7


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Awenta

Active member
Sep 28, 2014
4,090
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CT
Some little critters could've chewed up some wires

Still need codes though


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Austinflb7

New member
Aug 24, 2017
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Scanned the truck and got the codes P0380 and P1635. Also found some chewed wires along with some walnuts on the back of a connection that looks like it leads to a sensor. No clue what this sensor is but I have some pictures along with the same connection on an older lb7 of mine so that there is a better view.
 

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six5creed

Member
Jan 6, 2016
1,046
58
48
N.C.
Scanned the truck and got the codes P0380 and P1635. Also found some chewed wires along with some walnuts on the back of a connection that looks like it leads to a sensor. No clue what this sensor is but I have some pictures along with the same connection on an older lb7 of mine so that there is a better view.
Fuel pressure sensor. Here's a link to all the code #'s on your Duramax http://www.gmc4x4.com/topic/319-2001-2004-gm-lb7-duramax-diagnostic-trouble-codes/
 
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kheims

New member
Oct 7, 2012
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Also u might want to get a battery tender instead of letting the batteries go dead. Be much better for you. Defiantly fix the wires and keep the batteries from going dead. I know in my truck when I was having a bad battery the truck did some crazy things changed out batteries everything was good again.
 

JRein

Aircraft Mechanic's Hero
Sep 26, 2015
212
0
16
LRAFB, Arkansas
Best repair would be solder and shrink wrap the splice. I avoid butt connectors like the plague. They'll corrode or loosen with time and cause intermittent problems.

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Hambone

Always learning
Jan 24, 2016
572
0
16
Florida
Best repair would be solder and shrink wrap the splice. I avoid butt connectors like the plague. They'll corrode or loosen with time and cause intermittent problems.

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X2
Also like said battery tender and to add... get some poison so the squirrels and rats leave ya alone.
Or a Mean Tomcat lol
 

JRein

Aircraft Mechanic's Hero
Sep 26, 2015
212
0
16
LRAFB, Arkansas
X2
Also like said battery tender and to add... get some poison so the squirrels and rats leave ya alone.
Or a Mean Tomcat lol
I also will put bounce fabric softener sheets everywhere when I store a vehicle for any amount of time. I don't know why but rodents hate it

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N2BRK

Well-known member
Dec 31, 2009
1,907
233
63
Tub full of green coolant under the hood solved our wire-hungry squirrel problem.
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,329
1,615
113
Mid Michigan
Best repair would be solder and shrink wrap the splice. I avoid butt connectors like the plague. They'll corrode or loosen with time and cause intermittent problems.

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This is the only proper way to repair modern vehicle wiring. Make sure to keep twisted pairs twisted. Use similar gauge wire, too.
 

Austinflb7

New member
Aug 24, 2017
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The wires were chewed so far back it was unfixable. Was lucky enough to have extra harness laying around. Took old one off and put new one on. Fixed the problem. Thankyou for all the help guys.