Low/rough Idle

[pscoughlin]

I have a 2003 1500 4x4 with the 4.8, 105,000 miles. I had a code P0141 that indicated a bad O2 sensor. I went ahead and changed both O2 sensors, new plugs and wires, new air filter and a new fuel filter. The truck is stalling and the idle is around 300-400 RPM. The truck runs great when out on the road. Any suggestions.

[NothinButBowTies]

A couple of things I would do.

 

1. Clean the Idle Air Control Motor and Butterfly valve of the intake. - Make sure to get an intake safe cleaner.

2. Unplug the battery for a bit to clear out the PCM and force a relearn. There have been known issues with old mappings on a new tune up.

 

 

Just out of curiostity; once the O2 sensor was replaced, did the code come back?

[Bish]

A couple of things I would do.

 

1. Clean the Idle Air Control Motor and Butterfly valve of the intake. - Make sure to get an intake safe cleaner.

2. Unplug the battery for a bit to clear out the PCM and force a relearn. There have been known issues with old mappings on a new tune up.

 

 

Just out of curiostity; once the O2 sensor was replaced, did the code come back?

 

Ditto. I clean the IAC about once a year along with some top engine cleaner through the intake. On my Tahoe, the IAC gets all carboned up and she runs great after a cleaning. There is also a Idle Relearn (after cleaning) procedure that goes something like this.

 

Truck up to temp. Block wheels, parking brake on, put in drive and let idle for 5 minutes. Put into Park and idle for 5 minutes. Done.

 

I have followed the procedure twice and ignored the relearn and all 4 times it acted the same.

 

BTW- THe IAC is installed on the top of the Throttle Body towards the driver's side.

[pscoughlin]

A couple of things I would do.

 

1. Clean the Idle Air Control Motor and Butterfly valve of the intake. - Make sure to get an intake safe cleaner.

2. Unplug the battery for a bit to clear out the PCM and force a relearn. There have been known issues with old mappings on a new tune up.

 

 

Just out of curiostity; once the O2 sensor was replaced, did the code come back?

 

 

Yes, the code came back tonight when I started the truck. It idled rough then the code came after a few minutes. The truck never died, but the idle was rough.

[98 Z71 SLT]

I would make double sure that you replaced the correct o-2 sensor; there are 4 of them on your truck.

 

Check your fuses also--there are fuses for o-2 sensor heater circuits.

 

If all of that checks out good, take a reading of your fuel pressure.

 

If fuel pressure is within specs, replace your intake manifold gaskets. It is a dry intake-no coolant mess to worry about.