Late model GM fault code experts

[Truckedup]

The vehicle is a 2003 Chevy Silverado 4.8 5 speed manual.101,500 miles..Truck is stock except for a single Magnaflow muffler with dual exhaust.. I bought the truck recently and it appears to have been maintained properly .. The check engine light came on with a code PO174,"right bank lean"...No other stored codes. My code reader is 70 buck model...
Start up from cold and the engine feels a bit rough for maybe 10 seconds and then gets smoother .After a few minutes it's idling nice at 600 rpm..If the truck is started up cold and driven right down the road the performance is a bit soft for about 1/2 a mile. nothing serious, no coughing or backfire . After than it's fine...Once warmed up it runs strong with no hesitation, surging or sagging between gear shifts...And again the idle is smooth with no roll or surging....Always starts instantly hot or cold.
I checked all the vacuum hoses,PCV, the mass air sensor is clean and all intake pipes are in good shape. I realize it can be a variety of items, or nothing but maybe a "sensitive" computer.
I suppose if it runs well then don't worry about it? or should I dig deeper until the problem is found? I don't want to ignore a small issue that becomes a big issue because I didn't take the small issue.......Thanks

[Carnut1]

My first thought is the o2 sensor that covers that bank. With a better scanner you can read the o2 voltage while driving.

[midnightbluS10]

Download Torque Pro for Android and get an obd Bluetooth adapter. 20 bucks and you'll be much better off than with that code scanner. Be cautious of where you buy the adapter. There's quite a few fakes. The real ones are still inexpensive, though. It displays most all of the sensor data that the high dollar tools show. You can't program with it or do things like a CASE relearn, but it's a must have for any enthusiast that doesn't want to spend a fortune on a scan tool.




Diagnosing a P0174 is extensively covered all over the net. Do a quick Google for causes in gm trucks. Or diagnosis flowsheet. The info is there. You just have to want to look for it.

[Truckedup]

I discussed it with a few Chevy mechanics and a service writer, the first words from their mouth was "Intake Gaskets". They said the PO174 code and the rough running on a cold start is almost guarantees an intake leak.It's very common on truck LS engines..An hour job for experienced person...A bit longer for me...

[cfm]

Your symptoms very typical of intake gaskets leaking on those years.

I have replaced many for same reasons.

[JoePorting]

I had that code on my 2001 Silverado for years and could 't figure it out until one day I noticed the vacuum hose on the passenger side of the intake manifold that goes to the air pump had a big hole in it. Triple check for vacuum leaks. Use your ears more than your eyes. I heard the leak before I found it.

[Newold1]

Spray some water lightly around the intake manifold and hoses when the engine is first cold idling as you describe. If that water is sucked in while idling the engine will have a quick stumble and you can possibly locate the leak if that is the problem. Do not ever use any flammable sprays in doing such a test. I watched a guy in a shop do that and blow the plastic intake manifold to bits and nearly put himself in the hospital!

[Truckedup]

I had that code on my 2001 Silverado for years and could 't figure it out until one day I noticed the vacuum hose on the passenger side of the intake manifold that goes to the air pump had a big hole in it. Triple check for vacuum leaks. Use your ears more than your eyes. I heard the leak before I found it.

2003 is an electronic accelerator and Chevy simplified the wiring harness...The only vacuum hoses I see are some gizmo on top of the intake near the throttle body and the PCV. And the PCV valve is just an empty housing with a small hole for vacuum...

[Cogburn]

They updated the intake gaskets for those. They leak towards the bottom of the port cold. If you get both o2 sensors lean ,rough running cold,and a p0300 the gaskets are the culprit usually.

I have also seen injectors cause a p0174. If an injector is bad it usually shows up as a lean o2 sensor reading at WOT.

A bad maf can cause a lean condition at wot on both sides. Unplug it to see if the lean condition goes away at WOT.

An o2 sensor may short out hot, after driving a few miles it will drop towards 0v.

[Truckedup]

They updated the intake gaskets for those. They leak towards the bottom of the port cold. If you get both o2 sensors lean ,rough running cold,and a p0300 the gaskets are the culprit usually.

I have also seen injectors cause a p0174. If an injector is bad it usually shows up as a lean o2 sensor reading at WOT.

A bad maf can cause a lean condition at wot on both sides. Unplug it to see if the lean condition goes away at WOT.

An o2 sensor may short out hot, after driving a few miles it will drop towards 0v.

Perhaps, the engine pulls to redline with no problem. Surprisingly strong for 270 HP in a 4100 pound truck...Many late model stick shift late model vehicles have a few slight sags going through the gears, this one does not..
The engine does not appear to have been worked on so at 13 years I should replace the original intake gaskets just as "maintenance" And see what happens.. I'm retired and have the time...And my race bike project is stalled due to the usual issues...

[Rizzle]

Your symptoms very typical of intake gaskets leaking on those years.

I have replaced many for same reasons.

I discussed it with a few Chevy mechanics and a service writer, the first words from their mouth was "Intake Gaskets". They said the PO174 code and the rough running on a cold start is almost guarantees an intake leak.It's very common on truck LS engines..An hour job for experienced person...A bit longer for me...

I say most likely intake gaskets as well.

About 2 hours if you have no time constraints and haven't done them before, but know your way around modern efi engines.

[1989TransAm]

Could an exhaust leak between the head and the O2 sensor cause the same code?

[Cogburn]

Intake gaskets are easy and cheap to replace. I would check the knock sensors also while the intake is off. There are a bunch of youtube videos for knock sensor replacements that show the process.

[Truckedup]

Felpro gaskets and knock sensors are coming...My wife is surgical nurse on these daily driver repairs...A few 2x8's on bricks for an elevated work platform to reach all the way in .....Not too crowded under the hood and you actually see and touch the engine...Once the plastic intake cover and air intake pipe are removed ..

[JoePorting]

Could also be dirty injectors. Have you tried running a $4 bottle of fuel injector cleaner through the gas tank?