loss of power - Page 2

bradrhale · 05-08-2009, 11:43 AM

an 03 4.8 is not really bad but very much more involved than a pre MPFI engine. not every shop, im afraid, is going to have a good scan tool. you will need to check around for this. as for the coolant, how did your plugs look when you changed them?? you can have a pressure test done like gmc mentioned but for the price to have it done, you can probably buy your own. very simple device that hooks to the top of the radiator fill tube with a plunger that pressurizes the system. this will narrow down the possible leak spots. what part of the country are you in?? if you are close enough, id tell you to run it by and i would test that for you.

Butch Jones · 05-11-2009, 08:19 AM

im in maryland
i got a good deal on the converters its a magnaflow set up so im going to go ahead and change them as for the antifreeze ive been getting alot of people leaning towards the intake gaskets it looks to involved to do myself im shopping for a price now thanks for the input ill keep you informed im putting the converters on this weekend probably

bradrhale · 05-11-2009, 03:48 PM

hope the new cats helps the problem out with the loss of power that you are experiencing. do let us know how that turns out. i would let someone pressurize that system before you agree to an intake gasket replacement though.

hotrodpc · 05-13-2009, 08:49 AM

Yep, by all means, I would agree, get a pressure test first before you just pay someone to change intake gaskets. It would be bummer to pay for all that to find it was a head gasket, then you are paying for intake gasket parts and labor all over again. I would also tend to lean toward intake gaskets, but you ought to be sure first.

Butch Jones · 05-22-2009, 11:39 AM

i got my cats changed and truck is running better but not 100% im going to replace the thermostat and the trans filter this weekend
i put magnaflow performance cats on and i got 1 **** of a boost it definitly made a huge difference thanks for the guidence ill keep yous informed

Butch Jones · 06-17-2009, 06:38 AM

well guys after the cats my truck ran better but not 100% i replaced my fuel filter and got a kick *** difference the guts of the filter were broke off inside which was clogging the fuel line on take off the knock sensor was my fault when i changed the thermostat i got coolant everywhere so i hosed down the motor and got water in the knock sensor [note to self dont do that again] well in order to do the sensors i had to change the intake gaskets anyway im leaving for the mountains friday ill let you know if i lose any coolant thanks everybody for the help

Butch Jones · 06-30-2009, 12:59 PM

back from the mountains truck did great still a little sluggish but its only a 4.8 did not lose any antifreeze or overheat

gmctrucks · 07-02-2009, 12:52 AM

I'm glad it's running better you might replace your air filter with a K&N also check your timing and maybe it's time for a O2 sensor also use good replacement parts when doing a tune up not no auto zone trash. On you next trip add a can of Seafoam I use it all the time Lucas also has a good gas additive but I use Seafoam to clean all my injectors and so on. Get back to us and let know what goes.

05-13-2009, 08:49 AM	#14
hotrodpc Senior Member Join Date: Jul 2008 Location: OKC, OK Posts: 3,145	Yep, by all means, I would agree, get a pressure test first before you just pay someone to change intake gaskets. It would be bummer to pay for all that to find it was a head gasket, then you are paying for intake gasket parts and labor all over again. I would also tend to lean toward intake gaskets, but you ought to be sure first. __________________ *Winners NEVER Quit , Quitters NEVER Win !!!*

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05-08-2009, 11:43 AM	#11
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 8,014	an 03 4.8 is not really bad but very much more involved than a pre MPFI engine. not every shop, im afraid, is going to have a good scan tool. you will need to check around for this. as for the coolant, how did your plugs look when you changed them?? you can have a pressure test done like gmc mentioned but for the price to have it done, you can probably buy your own. very simple device that hooks to the top of the radiator fill tube with a plunger that pressurizes the system. this will narrow down the possible leak spots. what part of the country are you in?? if you are close enough, id tell you to run it by and i would test that for you.

05-11-2009, 08:19 AM	#12
Butch Jones Full Member Join Date: May 2009 Location: baltimore MD Posts: 21	im in maryland i got a good deal on the converters its a magnaflow set up so im going to go ahead and change them as for the antifreeze ive been getting alot of people leaning towards the intake gaskets it looks to involved to do myself im shopping for a price now thanks for the input ill keep you informed im putting the converters on this weekend probably

05-11-2009, 03:48 PM	#13
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 8,014	hope the new cats helps the problem out with the loss of power that you are experiencing. do let us know how that turns out. i would let someone pressurize that system before you agree to an intake gasket replacement though.

05-22-2009, 11:39 AM	#15
Butch Jones Full Member Join Date: May 2009 Location: baltimore MD Posts: 21	i got my cats changed and truck is running better but not 100% im going to replace the thermostat and the trans filter this weekend i put magnaflow performance cats on and i got 1 **** of a boost it definitly made a huge difference thanks for the guidence ill keep yous informed

06-17-2009, 06:38 AM	#16
Butch Jones Full Member Join Date: May 2009 Location: baltimore MD Posts: 21	well guys after the cats my truck ran better but not 100% i replaced my fuel filter and got a kick *** difference the guts of the filter were broke off inside which was clogging the fuel line on take off the knock sensor was my fault when i changed the thermostat i got coolant everywhere so i hosed down the motor and got water in the knock sensor [note to self dont do that again] well in order to do the sensors i had to change the intake gaskets anyway im leaving for the mountains friday ill let you know if i lose any coolant thanks everybody for the help

06-30-2009, 12:59 PM	#17
Butch Jones Full Member Join Date: May 2009 Location: baltimore MD Posts: 21	back from the mountains truck did great still a little sluggish but its only a 4.8 did not lose any antifreeze or overheat

07-02-2009, 12:52 AM	#18
gmctrucks Senior Member Join Date: Nov 2006 Location: Houston,Texas Posts: 4,030	I'm glad it's running better you might replace your air filter with a K&N also check your timing and maybe it's time for a O2 sensor also use good replacement parts when doing a tune up not no auto zone trash. On you next trip add a can of Seafoam I use it all the time Lucas also has a good gas additive but I use Seafoam to clean all my injectors and so on. Get back to us and let know what goes.