New Truck Rough Idle (annoying Jerk!)

[4wd]

My truck is new with only 3K miles (5.3l engine )and make an annoying jerk! (rough idle) after worm up, dealer say there is no code and it is normal and may be it is running very lean at idle, but the idle was fine during the first 2000miles.

 

It idles just above the 500RPM line and as it jerks the RPM moves up a little and returns. When in Drive it is fixed on the 500 RPM line and smooth out. I changed fuel but same.

 

Anyone experiencing this condition, any help...

 

thanks

[pm26]

Maybe the AFM (active fuel mismanagement) system is the culprit here?

[Z45]

AFM won't engage below 15mph. My truck idles about 550 RPM and jumps a little. Been like that since new. That's just the way they idle. The PCM slows the idle down as much possible to conserve fuel and emissions.

 

Maybe fuel system deposits, sometime is does not take long for them to form especially if short trip driving or using low grade fuel.

 

Try a GOOD fuel additive, sorry but most on WM shelves are worthless. My CTS was idling rough and hesitating. Dealer could find nothing wrong but installed a couple of PCM upgrades that should have improved it. Nothing changed so I put in some P.i. fuel additive and within a few miles (less the 50) it was running much better. Turned out the be nothing be dirty injectors. I only had 25,000 miles on the car and always used Shell 89 or 92 fuel (hi-perf V6).

 

I told a friend about that fuel additive and he put some in his old winter car that was idling real bad. By the time he came back from the gas station after filling up and adding it, it was idling better.

[saxdogg]

It is normal.

[mkelly]

My truck is new with only 3K miles (5.3l engine )and make an annoying jerk! (rough idle) after worm up, dealer say there is no code and it is normal and may be it is running very lean at idle, but the idle was fine during the first 2000miles.

 

It idles just above the 500RPM line and as it jerks the RPM moves up a little and returns. When in Drive it is fixed on the 500 RPM line and smooth out. I changed fuel but same.

 

Anyone experiencing this condition, any help...

 

thanks

 

My truck is doing the same thing. I have around 8k on it........ i have noticed that it doesnt do it when the outside temp is cold which leads me to believe that the fuel map is waaaay too lean.

[gnet158]

My truck is new with only 3K miles (5.3l engine )and make an annoying jerk! (rough idle) after worm up, dealer say there is no code and it is normal and may be it is running very lean at idle, but the idle was fine during the first 2000miles.

 

It idles just above the 500RPM line and as it jerks the RPM moves up a little and returns. When in Drive it is fixed on the 500 RPM line and smooth out. I changed fuel but same.

 

Anyone experiencing this condition, any help...

 

thanks

 

My truck is doing the same thing. I have around 8k on it........ i have noticed that it doesnt do it when the outside temp is cold which leads me to believe that the fuel map is waaaay too lean.

 

 

I have the same engine with 4,400+ but don't have the same problem. However it's never really cold here in CA, 50 degrees overnight. Tried Sea Foam?

[mkelly]

My truck is new with only 3K miles (5.3l engine )and make an annoying jerk! (rough idle) after worm up, dealer say there is no code and it is normal and may be it is running very lean at idle, but the idle was fine during the first 2000miles.

 

It idles just above the 500RPM line and as it jerks the RPM moves up a little and returns. When in Drive it is fixed on the 500 RPM line and smooth out. I changed fuel but same.

 

Anyone experiencing this condition, any help...

 

thanks

 

My truck is doing the same thing. I have around 8k on it........ i have noticed that it doesnt do it when the outside temp is cold which leads me to believe that the fuel map is waaaay too lean.

 

 

I have the same engine with 4,400+ but don't have the same problem. However it's never really cold here in CA, 50 degrees overnight. Tried Sea Foam?

 

 

 

 

I guess I should mention that I'm also at 7200 feet of elevation................... A lean map at sea level is a whole different issue up here

[4wd]

Thanks guys for sharing your experiences. I changed from 87 to 91.., and added detergent to the fuel, a little better.

 

The dealer insists it is normal because it runs lean at idle to save fuel, there are no codes and computer updates, it makes sens if it was acting like that from day one?!

 

I wish I know the fix!

[Bostonsfavson]

Thanks guys for sharing your experiences. I changed from 87 to 91.., and added detergent to the fuel, a little better.

 

The dealer insists it is normal because it runs lean at idle to save fuel, there are no codes and computer updates, it makes sens if it was acting like that from day one?!

 

I wish I know the fix!

 

 

I always suggest unhooking your battery for thirty minutes and then going for a drive. It's surprising how often this works.

[4wd]

Thanks guys for sharing your experiences. I changed from 87 to 91.., and added detergent to the fuel, a little better.

 

The dealer insists it is normal because it runs lean at idle to save fuel, there are no codes and computer updates, it makes sens if it was acting like that from day one?!

 

I wish I know the fix!

 

 

I always suggest unhooking your battery for thirty minutes and then going for a drive. It's surprising how often this works.

 

 

I will try...thanks

[petey_2788]

i have this issue too, i got 18,500 miles on my 07 i got the Ly2 4.8

 

does the EXACT same.. but sometimes the idle gets under the 500 RPM levels...like lets say im in park with the truck on and i put it in drive and slowly hit the gas, sounds like she wants to turn off...

 

weird...

[c4cruiser]

MY 08 with the 6.0L motor has a rough idle but it isn't a constant thing. It's most noticeable at morning startup after about 30 seconds and will still happen occasionally once the engine is up to operating temp. It only lasts for a couple seconds.

 

This rough idle is enough to see a slight movement in the tach needle and it shakes the radio antenna.

[RVJ]

My 08 5.3 has about 17,000 miles on it. I only use Top Tier Shell 87 Unleaded without ethanol. Every 3-4 tanks full I put a quality injector cleaner in the tank like Sea Foam or STP and it's smooth. Idles at about 1100 when first started but quickly falls to about 500 rpm. An occassional stutter is all I've witnessed while warmed up and idleing in gear at a stop light but it's so rare and minimal it's almost unoticeable.

[4wd]

My 08 5.3 has about 17,000 miles on it. I only use Top Tier Shell 87 Unleaded without ethanol. Every 3-4 tanks full I put a quality injector cleaner in the tank like Sea Foam or STP and it's smooth. Idles at about 1100 when first started but quickly falls to about 500 rpm. An occassional stutter is all I've witnessed while warmed up and idleing in gear at a stop light but it's so rare and minimal it's almost unoticeable.

 

If this was normal, then there is something wrong with all cars idling fine like the rest of the world.

[RVJ]

If your is that noticeable you've got a problem. I was merely telling you that horrible idling and jerking is NOT normal.