Rough idle is back with vengence

[Bob2C]

What is your fuel pressure on low side at idle? Mine is around 40-45psi. Goes up to 60-80 depending on demand when driving.


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[Floep]

The hose is in the tank as part of the fuel pump assembly, symptom may show up as low fuel pressure, which goes up as you put a jerry can of fuel into the tank. But it is not conclusive, the fact it idles rough and smooths out when raising fuel level is conclusive

 

[jwth]

couple of things come to mind,,,
water in the fuel tank- not unknown
cracked fuel pick up on the pump inside the tank,

 

[smokey_mountain]

Idle pressure is at 39-70, it fluctuates quite a bit.

 

[smokey_mountain]

With the WFH there is a lot less driving so hard for me to quantify the effect. Interesting observation from BlackBear folks, they see that my idle numbers in logs are rock stable, but the actual truck is shaking. Justin feels it is either injectors or a mechanical issue and not actual misfires. I am sure Justin knows his craft and saw 100s of 5.3s like mine. Problem is that I paid for a dealer to install brand new engine and transmission mounts, tech did the whole re-seating procedure, so mounts are likely to be properly installed.
Fuel pressure numbers I have posted above point to solid pressure numbers on both low and high. What I do not know on DI engines if pressure on idle should be ruler-flat stable or it can move up and down. This is a mystery. COVID situation brought us a recession and taking $12K loss on a vehicle is a plain wrong financial move, but dealers are clueless and not willing to do any work on the truck as it is "within spec". I now even question if engine is smoother on the full tank or this is my phantom wishful thinking.

The hose is in the tank as part of the fuel pump assembly, symptom may show up as low fuel pressure, which goes up as you put a jerry can of fuel into the tank. But it is not conclusive, the fact it idles rough and smooths out when raising fuel level is conclusive

 

[smokey_mountain]

For admins, can you please move this thread to 2015-2020 Engine forum

 

[smokey_mountain]

Can you please kindly move this to the 2018+ Forum? I have mistakenly started here.

 

[BG1988]

Can you please kindly move this to the 2018+ Forum? I have mistakenly started here.

what is the IAT showing & MAF showing? does the temp match the air temp on a cold start?

 

[Floep]

Sorry dvzz if I offended you, go to your desired place.

 

[smokey_mountain]

No offense at all. My truck is 2018 5.3 that is why I thought it was misplaced. I always appreciate all the help from all of you, folks.