Rough idling 2005 Chevy Silverado

[HopinImFloatin]

Re: Rough idling 2005 Chevy Silverado

if you are only seeing misfires on one cyl bank, try to swap the PRE cat. 02 sensors from side to side and see is the misfires move to the opposite side- the connectors may be the same and allow you to do so. Also, it is possible you have a converter begining to plug on the misfiring bank. A quick backpressure test will show that. Its possible but unlikely that a vacuum leak would cause a misfire on all cyls. on one bank.

 

[maproy99]

Re: Rough idling 2005 Chevy Silverado

Ok, not had any problems after the heat wave has cooled off. Hopefully it will not come back.

 

[maproy99]

Re: Rough idling 2005 Chevy Silverado

Well, it came back last night and it was cool out, so it is not related to heat but is random. I'll try switching the pre cat o2 sensors

 

[888]

Re: Rough idling 2005 Chevy Silverado

Try this. Spray carb cleaner on the odd side intake manifold/head while it's running. If it revs or stumbles, that's where your leak is!

I would try this first before you spend any money. Cracked/warped intake is very common problem on the 5.3.

 

[maproy99]

Re: Rough idling 2005 Chevy Silverado

I would try this first before you spend any money. Cracked/warped intake is very common problem on the 5.3.

Tried that, no change in rpm whatsoever.
However I did get my neighbor to ride shotgun with me to town and he noticed that the pre cat O2 sensors 1 was very stable, 600-800 range, but the other rapidly changes in the 40-700 range. So, the problem is the the O2 sensor readings. Hopefully it will be as simple as a bad sensor instead of something being all weird.

 

[888]

Re: Rough idling 2005 Chevy Silverado

Losing any coolant?

 

[maproy99]

Re: Rough idling 2005 Chevy Silverado

Losing any coolant?

Haven't had time to flip the pre cat O2 sensors yet. (Too much time working on the boat)
Not losing coolant.

 

[dolluper]

Re: Rough idling 2005 Chevy Silverado

Check your high and low fuel trim......spray around your injectors,see if rpm changes,check for green connection at #5 on ground {coil}

 

[maproy99]

Re: Rough idling 2005 Chevy Silverado

I was gonna flip the sensors today, but ran into trouble trying to remove the right sensor. (Kinda no room)
However with the left o2 sensor disconnected, the engine ran great for a test drive, only got an error code saying the preheater for the cat wasn't working (part of the o2 sensor and that was disconnected). Not sure if the engine goes in a loop or uses the right sensor to set the injectors on both sides. But the end result was I felt like the engine had better power at a given rpm and the misfire problem went away along with the rough idol. Going to get a replacement sensor tomorrow or Tuesday.

 

[lncoop]

Re: Rough idling 2005 Chevy Silverado

Great to hear. Glad it's not the cats.

 

[888]

Re: Rough idling 2005 Chevy Silverado

When ur in limp mode,it can and will cover up a lot of symptoms.

 

[maproy99]

Re: Rough idling 2005 Chevy Silverado

When ur in limp mode,it can and will cover up a lot of symptoms.

From what I have read I get a warning in the dashboard display that the engine is in limp mode and the engine will not exceed 2,000 rpm.
So, no limp mode, but the computer may be using the o2 sensor on the right side to set the ejectors on the whole engine. Or it is going in a loop. Hoping to pickup the new sensor tonight if I have time.

 

[888]

Re: Rough idling 2005 Chevy Silverado

From what I have read I get a warning in the dashboard display that the engine is in limp mode and the engine will not exceed 2,000 rpm.
So, no limp mode, but the computer may be using the o2 sensor on the right side to set the ejectors on the whole engine. Or it is going in a loop. Hoping to pickup the new sensor tonight if I have time.

Check engine light wasn't on after u unplugged O2 sensor? Then id say u got a bad pcm or some bad wiring.

 

[maproy99]

Re: Rough idling 2005 Chevy Silverado

Well, replaced the sensor today when I got home. Everything seems to be working perfect! Everything is as it should be.

 

[lncoop]

Re: Rough idling 2005 Chevy Silverado

Great news.

 

[dolluper]

Re: Rough idling 2005 Chevy Silverado

High + Low fuel trim readings will pinpoint fautly O2 sensors....plus irratic readings unstable esp at idle.....glad you got her truck on