Loss of power between 30-50mph - The 1947 - Present Chevrolet & GMC Truck Message Board Network

kdailey4315 · 04-27-2006, 10:54 PM

Hello all,
I need some help. When I'm driving and I reach about 30mph my truck seems to loose a bunch of power and this last till about 50mph. It doesn't cut out or die it just looses a lot of. I changed the cat and it got much better but it is still pretty bad. I had the tranny checked out and it is fine. I changed the fuel filter and gave it a complete tune up wires, plugs, cap, rotor, air filter and still have the problem. It's a gm crate 5.7l tbi engine with about 30k on it. Any ideas what it could be. I'm leaning toward the o2 sensor but I'm not sure. Since it launches from a dead stop fine and idles fine I don't think it could be fuel pump but I could be wrong. Thanks

greg0380 · 04-28-2006, 04:38 PM

maybe the EGR valve, try unplugging the vac line and plugging it with a golf tee.

Chevrolet4x4s · 04-28-2006, 09:25 PM

If EGR isnt it check your timing advance.
Hope this helps
Shane

04-27-2006, 10:54 PM	#1
kdailey4315 Registered User Join Date: Apr 2006 Location: Pacifica CA Posts: 66	Loss of power between 30-50mph Hello all, I need some help. When I'm driving and I reach about 30mph my truck seems to loose a bunch of power and this last till about 50mph. It doesn't cut out or die it just looses a lot of. I changed the cat and it got much better but it is still pretty bad. I had the tranny checked out and it is fine. I changed the fuel filter and gave it a complete tune up wires, plugs, cap, rotor, air filter and still have the problem. It's a gm crate 5.7l tbi engine with about 30k on it. Any ideas what it could be. I'm leaning toward the o2 sensor but I'm not sure. Since it launches from a dead stop fine and idles fine I don't think it could be fuel pump but I could be wrong. Thanks Last edited by kdailey4315; 04-27-2006 at 10:54 PM.

04-28-2006, 04:38 PM	#2
greg0380 Registered User Join Date: Dec 2003 Location: CT Posts: 454	Re: Loss of power between 30-50mph maybe the EGR valve, try unplugging the vac line and plugging it with a golf tee. __________________ 1985 GMC Sierra 1500, 1/2 ton, 2WD, LWB, TBI 305 5 speed, 3.42 rear 2007 GMC Sierra 1500, xtended cab, 4X4, flexfuel 5.3L 1999 BMW 528i

04-28-2006, 09:25 PM	#3
Chevrolet4x4s Registered User Join Date: Nov 2005 Location: WV Posts: 227	Re: Loss of power between 30-50mph If EGR isnt it check your timing advance. Hope this helps Shane __________________ 1993 K1500 350 5 speed 1985 K10 Silverado Vortec 406 5 speed (in body shop) "I been drivin' this '85 pickup truck Them buddies of mine call it a bucket of rust She's a little beat up but she still runs like the wind Yeah, kinda like me I been banged and bruisedBeen around the block a time or two But I'm runnin' like new goin' places I never been No, I ain't broke I'm just broken in" 1963 Dodge Townwagon(its amazng what 30 years and zero miles will do to a vehicle ) Member#20327



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