Join Date: Dec 2014
Posts: 3
Need help limp mode
I recently bought a 2005 gmc sle.It has 185,000 miles.I changed fuel filter ,oil ,and the screw on trans.filter before a road trip.250 miles into trip running 75-80 truck lost power and would not turn over 2000rpm.Turned truck off 're started and made 100 more miles before did it again.I can start truck up and can rev to any rpm.I can go down road and when it gets to about 2300-2500 rpm won't rev any higher then it bogs till you go below 2000 rpm.It will run and shift fine as long as you don't go over 2000 rpm.Once truck reaches the 2300-2500 rpm range if I let out of it it never goes into limp but if I get it to the 2300-2500 rpm and hold it ther trying to make it go after about 2-3 second it will go to the limp mode.I'm getting no check enginr light.I've already installed race valve and new fuel lines at filter housing.Any help will be greatly appreciated.
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Mine did something like that , No check engine light but I did have codes stored.
Limp mode cuts out cylinders and makes a hell of a racket , I would shim the injector rails pressure relief valves

 

Look at BUYING A LLY post below and it has side bar videos on the relief valve. Let us know how you make out