2002 little power

my 2002 silverado with 4.8 will start and run but put in gear it has no power. wont rev over 1500 rpms. possible cat blocked or fuel filter?

my 2002 silverado with 4.8 will start and run but put in gear it has no power. wont rev over 1500 rpms. possible cat blocked or fuel filter?

May be one or several of many things.
What is the mileage and when was last good tune up?
What is the fuel pressure readings?
Any check engine lights on or flashing.

For a plugged exhaust post back vacuum readings at idle and 2K RPM.

138,000 miles. bought truck in november 08. just changed plugs. no change. engine light came on and flashed when first acted up. havent done any testing yet. out of work right now but when i get the funds i will test fuel pressure. is there special tool for testing fuel pressure.

Check for codes and if light is flashing when running you have a cylinder mis.
Post back code no.

thanks for your help. i will post back when i figure more out. the light is no longer on but i havent gone any where with it . since it barely moves.

IT could possibly be the mass air flow sensor. My Silverado acted up almost the same way and that is what it was. But as suggested, get the codes scanned, it can get costly just guessing and throwing new parts at a problem when you are unsure.

You should be able to borrow a fuel pressure tester from the parts store. It connects to a quick-connect fitting on the fuel supply line (looks like an A/C connector but should be near the firewall on the driver's side). A low pressure could be a failing fuel pump ($$$) or a bad fuel pressure regulator ($).

What happens when you try to rev it past 1500 rpms? Does it feel like the truck tries to move? Does the engine sound like it is bogging (no missing or roughness) or does it start to stall?

Another possibility is the O2 sensors are due for replacement.

Hope this helps!

it sounds okay in park but in gear it wont rev over 1500. it boggs down.

when it first acted up i was driving about 25 mph i stepped down on the gas pedal and bogged right down. when id hit the gas the engine light would flash and it wouldnt rev over 1500rpms. i changed the plugs and unhooked the battery and changed the plugs. took it down the road and light came back on and flashed as i stepped on gas still no power. i un hooked the battery again. then the next day hooked it back up and started the truck. starts right up but in gear wont rev just boggs down. thanks for the help.

is it 2wd and if so doesnt it have the traction assist unit?

The code reading should be free at the parts store as well as the fuel pressure tester loaner. Just because the truck's CEL isn't on doesn't mean there aren't stored codes. It will keep the trouble code history until it is cleared by a scan tool.

Another thought could be the throttle position sensor based on your description of symptoms. It could be errantly reading a wide-open throttle, feeding too much fuel for the air being taken in.

Check the codes & let us know what you find...at least that's free.

Simple thing, check all of your fuses. I had a similar situation where I blew a fuse that basically shut down the left bank of my engine, making my V8 a 4cyl. I believe it was the fuse for the injectors, and the SES light flashed scaring the crap out of me. But checking fuses is free and well, hey you never know.

JUST hooked to obd2. codes P0122, P0300 AND P0443. Is throttle position senser causing random mis.

JUST hooked to obd2. codes P0122, P0300 AND P0443. Is throttle position senser causing random mis.
No.
Proper testing will give the answers.
Have you done any testing as asked for?

JUST hooked to obd2. codes P0122, P0300 AND P0443. Is throttle position senser causing random mis.


I would check the throttle position sensor connector for damage corrosion....then If necessary using an OHMMETER measure the resistance while moving the throttle to see if the resistance drops out to infinity[open]...3 wires gray , blue, and black...black is common [ground].
the blue is the connection that will vary resistance as the throttle is changed..

gray is the PCM/computer reference voltage feed of 5volts,,when the engine /ignition switch is on...

this is very possible .....as your problem..let us know what you found..

tested fuel pressure. 57 key on. 50 running. pressure stays over 55 doesnt seem to be leaking. when I put in gear and hold the brake pressure goes over 50. Is this telling us pump is good or bad?

tested fuel pressure. 57 key on. 50 running. pressure stays over 55 doesnt seem to be leaking. when I put in gear and hold the brake pressure goes over 50. Is this telling us pump is good or bad?

when the engine is running the pressure spec is min 53psi,,members have found that with a pressure of less than 53-52psi the engine has problems....

restrictions in the fuel lines, a faulty regulator,,or a weak fuel pump,,,the fuel pump relay .....drive around with the fuel guage on and see how much it drops below the 53psi...

make sure the pressure guage is accurate as well..

Took my truck to mechanic. Leaking intake gasket. Should be done by tomorrow.