2005 silverado..5.3...motor idle rough.. getting 3 codes

Have you had the engine control unit scanned for fault codes? Is this oil smoke or fuel?

I had the same problem on my 2001 Sunfire (same car as the Cavalier-different branding) which I was able to fix successfully.

My symptoms were:
-Traction Control OFF light illuminated
-Cooling fan running even if engine cold and it was freezing outside (I also noticed that when the Traction light illuminated, the fan would then begin)
-Rough idle with black smoke when cold
-Poor fuel economy


I have a code reader which produced codes P0130 and P0171. These are error codes for the upstream oxygen sensor (the one under the hood).

I simply replaced the O2 sensor (it took me 10 minutes). I did not reset the check engine light after the repair as I wanted to see what the car would do on its own. The idle was much smoother with no smoke and the cooling fan stopped running unnecessarily. After 1/2 mile down the road, the Trac light went away and the system functioned normally. I tested this by trying to accelerate quickly up a snowy driveway. I also noticed that the acceleration and shifting (auto tranny) were smoother. I reset the check engine light. All is satisfactory.


What was happening to the car before the repair:

P0130 is usually for a bad O2 sensor and P0171 is the sensor detected that the motor was running too lean (but it actually wasn't-the sensor was essentially giving a false lean signal).
The rough idle, black smoke, and poor economy are due to running too rich. In my case, the sensor told the PCM (the car's computer) that the air/fuel mixture was too lean. In response, the computer said "OK, more gas!" That's why it ran rich. This was evidenced on the old O2 sensor as well...it was completely caked with carbon from an excessively rich mixture. This further destroyed the performance of the O2 sensor.

If the check engine light is on, you would need to check the computer for trouble codes first.
If the engine is fuel injected, it could be a bad injector. If it has a carb, it could be a sticking choke or an internal leak.

I'm sure your check engine light is on try....
https://www.autozone.com/landing/page.jsp?name=top-five-reasons-check-engine-light

If there is a vac leak or a split in the hose between the intake and the MAF you can get a code for the sensor. The code is saying the data from the sensor is not what it should be, not necessarily that the sensor has failed.
Clogged air filter or box could cause a problem too.

Could be a idle air problem. The injector could be leaking when you shut it off ..Try some injector cleaner see if it gets better..The idle air shouldnt run rough just idle real low or sometimes it will get stuck and idle high....Are you losing any antifreeze..If you are the 2.0 SOHC engine bad about leaking antifreeze into the cylinder and makes the engine run rough until it burns it out..See if you can see the smoke coming out when it happens..White smoke indicates antifreeze,,Black smoke indicates fuel..

Black smoke could mean it is running rich, have a scan done, it is probably an engine misfire code and it will tell you which cylinder is misfiring. the last digit is the cylinder, unless it says random missfire, It may be time for a good tune up and don't forget the fuel injection system, Clean out the intake and do an induction cleaning on the injectors.

PO229 indicates tps circut inttermitent.
Po300 303 and 304 indicate missfires on cyl 3 and 4.. Was the fuel filter primed before starting the engine? If not ,remove and reinstall filter. Then prime filter with pump that is on fuel filter adapter. Once this is done restart and verify o/k

coolant temperature sensor boken, check and replace if defective.

Try cleaning the EGR valve first



electronic Tempture Control
ECT sensor
symptoms
Potential Symptoms

Symptoms of a P0118 could include:

* Very poor fuel economy
* A no start condition
* Vehicle may start, but run very poorly, blowing black smoke, running very rough and misfiring
* Illumination of MIL
EGR valve

Usually a fault in the control circuit, will leave no noticeable symptoms other than the Malfunction Indicator Lamp (MIL) illumination. However, if the EGR control solenoid
is stuck open due to debris, etc. the code may be accompanied by misfire under acceleration, rough idle, or engine dying altogether.