2015 Silverado Sputters.

[motoxgolf11]

So I have a 2015 Silverado with the 5.3L Non-Flex Fuel engine and when I'm stopped at a red light it drops below the 500rpm idle. I've also noticed that at slow speeds through a parking lot it has this sort of chug chug feeling. I also noticed tonight while driving down the freeway with the cruise set at 70 it had a delay when trying to climb a hill. I do have 173k on it and don't know where to start. I will be looking at the air filter since I haven't changed it since the beginning of the year. But not sure what else it could be? I don't think these models have a fuel filter, but I do know that the fuel filter is notorious for going bad. Any advice helps. Thank you.  

[silveradosid]

at that mileage, plugs and wires and look for broken exhaust bolts

[Lsgun1]

The below 500 idle is normal, my 18 does it and has since new. A lot of complaints about it because it feels like  it's going to stall but that's how they programmed the idle for some reason. 

 

Cruise could be in 4 cyl then going back to v8.

 

Don't know what a chug feeling is but when is the last time you changed the spark plugs?

[stevejones]

Hi pressure fuel pump is my interweb guess....

[KevenN43]

Going through this with my'17 now. Plugs and wires were done last year, changed the tranny fluid and a few months later I am looking at rebuilding it. Also installed new fuel pump as the pressure was a little low but not bad. Still not that much improvement. GMC shop is telling me the misfiring is from the tranny slipping. They can't tell me exactly what it will cost other than 2000.00 in labor plus parts. 

Thinking I will just trade it in and stop throwing money at it hoping this issue goes away. 

[motoxgolf11]

I recently changed the plugs. It was either last year in December or at the start of 2020. I recently also had the tranny rebuilt as well IN June 2020. So i'm looking at either wires, coil, injectors, or fuel pump is what I'm gathering.  

[motoxgolf11]

So I went out and bought a OBD reader. I was driving down the freeway tonight and while climbing a hill I had another misfire. It struggled up the hill and I barley made it off the freeway and I got the big flashing service light come on. I had my reader with me and plugged it in and it was reading back as a random misfire. Once I got to where I was going and parked I went through and checked some things. The fuel pressure was reading at 42psi at idle and would climb as I pressed the throttle. But I also noticed that it also told me my alternator is bad as it is overcharging my system. The meter gage in the dash has been sitting at 14volts when it normally would read between 9-14. I’m thinking the alternator is cutting out under a load. It drive fine on surface streets so I think it’s the alternator. Any one have any thoughts on this?

[silveradosid]

if it is driving fine on surface streets but struggling on hills , i would double check the plugs and if they are ok, then i would think your cats are getting plugged up

[jagabom (Esquire)]

Some have raised the idle a hundred rpm to get rid of the idle shudder.  They said it worked.

Jim

CYWG

Edited November 14, 2020 by jagabom (Esquire)