Silverado 5.3 L is misfiring
Asked by Gary Mar 16, 2015 at 07:43 PM about the 2000 Chevrolet Silverado 1500 LS RWD
Question type: Maintenance & Repair
My Silverado has a misfire when a
load is put on the motor ie going
up a steep grade or hill. Cruising
down the highway at 55 mph,
transmission in overdrive, the
rpm's drop to around 1500 or 1400
the motor starts misfiring. I
usually drive with the cruise
engaged and if the rpm's drop any
further it will kick into passing
gear and everything smooths out.
If you put your foot in it, the thing
will spit and spat and even
backfire before you get up enough
power to pass or finish climbing
the hill.
Get this, I got someone to connect
a code reader to it. NO CODES! I
replaced the fuel filter under the
cab. No good.
Do I have a bad spark plug? Bad
plug wire? Or do I have an internal
problem that the truck computer
brain will not pick up?
11 Answers
sagomonkey answered 9 years ago
Has the check eng light ever come on while it's acting up
Check engine light has never come on. I get the usual like, change oil, low washer fluid, low coolant and such but no check engine.
sagomonkey answered 9 years ago
you're going to have to have a scanner hooked up while it's doing it then you can see live What cylinders are misfiring.it is a 5.3 and not a 5.7.right just making sure
5.3, that's the 327 I believe and the 5.7 is a 350? I have a 5.3 according to the vin#
sagomonkey answered 9 years ago
Need that scanner .you will save way more money that way than guessing
How much for one? I've never priced them.
That was my first guess but it's a little strange that the check engine light or any codes haven't come up. Anyway, you are correct, it is due for a tune up. Thanks for your help Jim and sagomonkey! I appreciate it! Think I'll start doing a little customizing now.
Jbarnewman answered 5 years ago
Hey there, did you ever figure out what was causing your truck to misfire? I have a Suburban with the same motor and same problem!
I have 2012 suburban with same issues. Changed out all plugs and wires today and issue remains.
Rigsby9675 answered 5 years ago
Same thing happening to my 2008 gmc series 5.3l, I’ve changed the plugs wires throttle body sensor map sensor, done throwing parts at it
My 2007 was doing the same thing. Seemed to run ok at idle with feeling a slight misfire. When I put it under a load, all kinds of things went wrong. No power, sounded like it was dieseling just crap. I did a smoke test for the intake, and various other tests. I pulled out the O2 sensor in front of the cat on the passenger side and left the hole open and the O2 sensor plugged in. Made all of the difference. Drilled a 1-1/4 in hole into the back of the cat and hogged it out. Come to find out the cat was clogged and putting back pressure into the exhaust valves. This caused lots of issues. Runs so much better. Try testing the catalytic converters!
