6.2l Engine Stumbles Upon Startup

[plumber802]

Hey guys.Truck has about 6000 miles on it.When I start it warm or cold,just when the engine fires there is a significant pause/stumble then it catches and smooths out fine.On Friday it cranked for longer than usual and kept cranking even after I released the key.It started after a short period and ran fine after.Does anyone know what might be happening before I bring it in for service?Thanks for any help.

[dlewis1111]

Hey guys.Truck has about 6000 miles on it.When I start it warm or cold,just when the engine fires there is a significant pause/stumble then it catches and smooths out fine.On Friday it cranked for longer than usual and kept cranking even after I released the key.It started after a short period and ran fine after.Does anyone know what might be happening before I bring it in for service?Thanks for any help.

 

As far as cranking goes, these trucks are programmed with a start sequence in order to avoid damage to components. In mine you can just bump the key and it will still continue cranking until started. This is "normal" and I believe the owners manual talks about it.

 

Is your air filter clean? Have you checked the MAF sensor to make sure its clean? Random thoughts, but you are still under warranty so I would take it in.

[RyanbabZ71]

Hey guys.Truck has about 6000 miles on it.When I start it warm or cold,just when the engine fires there is a significant pause/stumble then it catches and smooths out fine.On Friday it cranked for longer than usual and kept cranking even after I released the key.It started after a short period and ran fine after.Does anyone know what might be happening before I bring it in for service?Thanks for any help.

 

As far as cranking goes, these trucks are programmed with a start sequence in order to avoid damage to components. In mine you can just bump the key and it will still continue cranking until started. This is "normal" and I believe the owners manual talks about it.

 

Is your air filter clean? Have you checked the MAF sensor to make sure its clean? Random thoughts, but you are still under warranty so I would take it in.

 

 

Re-read

 

Truck has about 6000 miles on it

 

Doubt the air filter has any hint of dirt with only 6K miles.

[plumber802]

Hey guys.Truck has about 6000 miles on it.When I start it warm or cold,just when the engine fires there is a significant pause/stumble then it catches and smooths out fine.On Friday it cranked for longer than usual and kept cranking even after I released the key.It started after a short period and ran fine after.Does anyone know what might be happening before I bring it in for service?Thanks for any help.

 

As far as cranking goes, these trucks are programmed with a start sequence in order to avoid damage to components. In mine you can just bump the key and it will still continue cranking until started. This is "normal" and I believe the owners manual talks about it.

 

Is your air filter clean? Have you checked the MAF sensor to make sure its clean? Random thoughts, but you are still under warranty so I would take it in.

 

 

 

OK I didn't know about the starter sequence.Sounds like it just kept cranking on its own until it fired.

Today it stalled once right after it started then ran fine after I started it again.Not normal.I'll bring it in to be checked.

I don't think the air filter is dirty since the truck barely has 6K miles on it.

[Bish]

Hey guys.Truck has about 6000 miles on it.When I start it warm or cold,just when the engine fires there is a significant pause/stumble then it catches and smooths out fine.On Friday it cranked for longer than usual and kept cranking even after I released the key.It started after a short period and ran fine after.Does anyone know what might be happening before I bring it in for service?Thanks for any help.

 

As far as cranking goes, these trucks are programmed with a start sequence in order to avoid damage to components. In mine you can just bump the key and it will still continue cranking until started. This is "normal" and I believe the owners manual talks about it.

 

Is your air filter clean? Have you checked the MAF sensor to make sure its clean? Random thoughts, but you are still under warranty so I would take it in.

 

 

 

OK I didn't know about the starter sequence.Sounds like it just kept cranking on its own until it fired.

Today it stalled once right after it started then ran fine after I started it again.Not normal.I'll bring it in to be checked.

I don't think the air filter is dirty since the truck barely has 6K miles on it.

 

 

Definitely shouldn't stall! Mine has never stalled in almost 70K. My Denali starts fine but stumbles a little if you give it gas in gear during the first 30 seconds or so after a start. Low miles so it is not likely maintenance item yet but definitely check the air filter in case. I would say maybe dirty injectors or dirty throttle body but again not likely at your mileage. Definitely worth a trip to the dealer IMO. What do you usually run for gas? Could be a bad tank of gas.

[ColoradoSkiCountry]

The 5.3s in my 99 and 07 did the same thing. No big deal but they never stalled out just rough idle for a sec or two.

[Z45]

Engine stumble in the first few seconds of operation are nothing unusual. Maybe its just the fuel you are using, try a better brand of fuel.

[plumber802]

You guys are bringing up a good point about fuel.I have been running on regular since new because all my miles are highway with no towing/load.This might be the problem.I will gas up when the tank is almost empty and report back.

 

PS. Don't hate on me for running regular.I checked with the service mgr about this when I bought the truck and he said no problem as long as the truck wasn't working hard or towing.

[Z45]

If you are using poor quality fuel (usually cheap fuel is) fuel system can gum up in a matter of 5,000 miles or less. Always use top tier fuel.

 

 

If the vehicle has the 6.2L V8 engine (VIN Code 2), use

premium unleaded gasoline with a posted octane rating

of 91 or higher. You can also use regular unleaded

gasoline rated at 87 octane or higher, but the vehicle's

acceleration could be slightly reduced, and a slight

audible knocking noise, commonly referred to as spark

knock, might be heard. If the octane is less than 87, you

might notice a heavy knocking noise when you drive.

If this occurs, use a gasoline rated at 87 octane or

higher as soon as possible. Otherwise, you could

damage the engine. If heavy knocking is heard when

using gasoline rated at 87 octane or higher, the engine

needs service.

[Knowklew]

run premium gas

clean the MAF with MAF cleaner, dont touch the wires

[tonygxp]

169 gallons of fuel used (2600mi trip to and from Disney) @2.95gal super vs @2.74gal regular what would you save? $35??? big deal.. Think about that next time you put regular in your how many thousand $$$$$ trucks lol..

[plumber802]

If you are using poor quality fuel (usually cheap fuel is) fuel system can gum up in a matter of 5,000 miles or less. Always use top tier fuel.

 

 

If the vehicle has the 6.2L V8 engine (VIN Code 2), use

premium unleaded gasoline with a posted octane rating

of 91 or higher. You can also use regular unleaded

gasoline rated at 87 octane or higher, but the vehicle's

acceleration could be slightly reduced, and a slight

audible knocking noise, commonly referred to as spark

knock, might be heard. If the octane is less than 87, you

might notice a heavy knocking noise when you drive.

If this occurs, use a gasoline rated at 87 octane or

higher as soon as possible. Otherwise, you could

damage the engine. If heavy knocking is heard when

using gasoline rated at 87 octane or higher, the engine

needs service.

 

 

 

 

Been using Shell since new.

[L29er]

mine did this once to me, i only have 3000 miles. i run 91 shell fuel since day one. i`m starting to get a long list of issues, sad, I love the truck.

[plumber802]

Hey guys.Truck has about 6000 miles on it.When I start it warm or cold,just when the engine fires there is a significant pause/stumble then it catches and smooths out fine.On Friday it cranked for longer than usual and kept cranking even after I released the key.It started after a short period and ran fine after.Does anyone know what might be happening before I bring it in for service?Thanks for any help.

 

As far as cranking goes, these trucks are programmed with a start sequence in order to avoid damage to components. In mine you can just bump the key and it will still continue cranking until started. This is "normal" and I believe the owners manual talks about it.

 

Is your air filter clean? Have you checked the MAF sensor to make sure its clean? Random thoughts, but you are still under warranty so I would take it in.

 

 

 

OK I didn't know about the starter sequence.Sounds like it just kept cranking on its own until it fired.

Today it stalled once right after it started then ran fine after I started it again.Not normal.I'll bring it in to be checked.

I don't think the air filter is dirty since the truck barely has 6K miles on it.

 

 

Definitely shouldn't stall! Mine has never stalled in almost 70K. My Denali starts fine but stumbles a little if you give it gas in gear during the first 30 seconds or so after a start. Low miles so it is not likely maintenance item yet but definitely check the air filter in case. I would say maybe dirty injectors or dirty throttle body but again not likely at your mileage. Definitely worth a trip to the dealer IMO. What do you usually run for gas? Could be a bad tank of gas.

 

 

 

 

I've been running Regular and filling up at the same Shell station even the same pump so I can keep my fillups consistent for verifying mpgs.I don't think its bad gas since its been doing it for several fillups now.

[plumber802]

I have an appointment to bring the truck in on Thursday.Unfortunately,it only does this when it has been sitting all night or during the day.Dealership doesn't give loaner cars any more so I have to bring it in on my way home from work.Maybe they have a TSB on this.I'll keep you posted.