03 4.3 silverado runs weak

Asked by Mar 26, 2016 at 01:28 AM about the 2003 Chevrolet Silverado 1500 Short Bed 4WD

Question type: Maintenance & Repair

ChrisCharles65 ChrisCharles657 hours ago
i have an 03 silverado 4x4 4.3 and my
truck just runs weak. like i cannot gain
speed going up a hill. the only was to keep
a contant speed is to the floor. i changed
plugs and wires and distrubter cap and
rotor cap, plugs and wires. changed the oil
and filter, tranny fluid is good. has a miss
when i'm barely giving it gas. the cat is cut
off the exhaust and comes out right behind
the cab. it has like 133k miles. i really like
the truck, i just cant figure out why its
running so weak

25 Answers

also the fuel pump and fuel filter, ran the codes at first and it read the mass air flow sensor, changed it, code went out, truck still runs like dish water. been running lucas gas treatment in it since i've been driving hoping to get all the junk out of it. when it pulls out it feels like it has all kinds of power just went up to speed like 40-55 and you try kicking it. it feels like its kicking down but not like getting the power it should. i really need some help here. its a 4.3 vortex with an auto tranny


Well, you can't run without the catalytic converter for one, along with properly working 02 sensors. So it goes great for ya when it is cold, right? See the computer cannot get into a closed loop at operating temperature, there for not adjusting the air fuel mixture properly. I bet if you pull a plug it will be black.

also now the my air is only working on the passenger side. i thought it was perfectly okay to run w/o a cat


Between the catalytic converter, the 02 sensors, and the temperature sending unit, the OBDII adjusts for the proper air fuel mixture going into the cylinders. The OBDII needs a cat to work properly.

but would it make it run like dish water? lile its drivable i've been driving it for anout a month now. i get like 17mpg. and what i'm saying is, when i kick it down like to the passing gear, i still lose speed. and it also doesnt seem to hold a gear long enough like it should. i dont feel like its the tranny. the fluid is good and all, no burnt smell or anything. but i'd got a miss at about 200rpms its like its not getting the right amount of air

thank you for the help btw. i really appreciate it


Have you ever checked it for codes? Isn't there a check engine light on?


And yes it would.

yes it just reads the o2 sensors. i have a grand for the truck. put all them parts on it and it ended up being a crank sensor. battery was dead and i had to charge it so i lost all codes. when i got it running, it said missfire on cylinder 1 then it read mass air flow sensor and i changed it. now i'm stuck here trying to fix it. i really like the truck, but i cant figure out. why the fender on the passenger side is pushed in some, then hit a rock clif would not having a good air way do anything?


Yes if the inlet is restricted by the opening by the fender.

so i should check the cat and the fender right?


That would be a start. Pull the air box off and see if it is restricted at the inlet of the air box. You said the cat wasn't on the vehicle, how are you going to check it? Can you look inside to see if any of it is plugged up?

like as in check and see about putting a cat on it. it blows pretty good. wouldnt thing it would be clogged up


I think you would be wise to get a new cat. They don't have to be plugged up to be bad either. When they go bad, & not by plugging up, the 02 sensors can still pick up bad emissions that the cat is suppose to take care of. The way your truck is set up, you can't get away from bypassing anything because of the OBDII computer. I would work on getting it back to the way it is suppose to be.

i wish i could send you all videos


Give it a shot. ruohomaki.ron@hotmail.com

Best Answer

should be on its way


not here yet...

i sent it 2 different ways.


Try just shooting me an e-mail from your account. You know it is not going to work off of Carguru.

i did

its still sending.


"Link me up Scotty"


Did you crash? May have to hook me up with you tube or something.

i aint got youtube, did it send it?

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