Hello, Wondering if someone can help. I have a 2000 Silverado 4.8 with 134,000 miles and I have done every tune-up you can think of. I have a bit of a ruff idle and would like some opinions on what it can possibly be. Here is a list of things I have change and maintenance:

Spark Plugs
Spark Plug Wires
Coils
Dealer Fuel system Flush
Fuel Filter
Fresh oil/filter synthetic every 3k

 

Gonmoises,

A dizzying array of faulty parts could cause rough idle symptoms, but here are a few that I can think of off the top of my head:

1) Oxygen sensor- Oxygen sensors can control or contribute to many different engine functions, including fuel/air mixture, engine timing and engine combustion intervals. A faulty oxygen sensor can disrupt any of these things and cause a rough engine idle. Typically, a bad oxygen sensor will throw a code but if it is in the process of dying then it may not register an official code.

2) Throttle body- A dirty throttle body that's plagued with carbon deposit build-up can occasionally cause a wavering or rough idle. Purchase some throttle body cleaner and proceed to clean out the TB in your truck. It's an inexpensive solution, but it's just crazy enough to work

3) PCV valve- The PCVsystem removes and recycles accumulated gases that escape into the crankcase of a vehicle's engine from the combustion chambers. Instead of becoming combusted and exhausted from the engine, these gases build up in the crankcase and create higher internal pressure. The PCV valve directs these gases back into the combustion chambers and plays a vital role in maintaining engine efficiency.

You can remove and inspect the PCV valve by shaking the part back and forth. If the PCV valve is malfunctioning or becomes clogged, you will hear no sound when you remove and shake it. A functional PCV valve should make a rattling noise if shaken.

Rough idle is one of the chief symptoms of a bad PCV valve. Thankfully, the PCV valve is relatively cheap. I did a little bit of research and it runs about $17 at the stealership and $12 at gmpartsgiant.com. That was the cheapest OEM replacement part that I could find.

Conduct the aforementioned test and if you determine your PCV valve to be bad then replace it.


Let me know if you need more help tracking down the culprit behind your truck's rough idle