5.3 won’t run good when warmed up

[HiHoeSilver]

See my post above for some starting points

Yup. Something when it goes into closed loop.

 

[JetBlackNali]

Almost sounds like flooding. Easy enough to check fuel pressure.

 

[Tonyrodz]

Hey guys, I have an 05 Yukon and it started stuttering today and wouldn’t wouldn’t take any throttle without bogging down, I babied it and got it about a mile away from my buddies and it gave up on me, I towed it to his driveway and went back later on in the night night and it started no issue, until it got about halfway to temp, then it would sputter under any load, and would idle ok but surge every 30 seconds. I checked wires, I have to get ahold of a code reader tomorrow but does anyone have any ideas as to what it could be? Fuel pump was done almost a year ago, anything would help, thankyou guys!

Sounds like it might be the fuel pump. I had mine replaced and that 1 died 1 week later, got me stuck.

 

[iamdub]

X 365,738 on checking fuel pressure. Your symptoms match those of a fuel pump getting weak as it warms up. It may not be directly related to the temperature of the engine. Not saying it's definitely the problem, but the fuel supply is the first item I'd try to rule out. Need to fill your tank? If you can't get (borrow) a pressure tester soon, you can drive near gas stations until it starts to act up (or idle it at a gas station) then fill up the tank immediately and see if the problem goes away. The fresh gas should cool off the pump and you'd see an immediate improvement rather than having to wait the normal lengthy cool-down period. The downside is that if it is the pump, you now have a full tank of gas to contend with. Once you rule this out, then you can move on to the deeper possibilities, such as those that involve checking temperature-related electronic failures. A good scan tool that can read live data would really help at that point.

 

[Jarrett McClune]

X 365,738 on checking fuel pressure. Your symptoms match those of a fuel pump getting weak as it warms up. It may not be directly related to the temperature of the engine. Not saying it's definitely the problem, but the fuel supply is the first item I'd try to rule out. Need to fill your tank? If you can't get (borrow) a pressure tester soon, you can drive near gas stations until it starts to act up (or idle it at a gas station) then fill up the tank immediately and see if the problem goes away. The fresh gas should cool off the pump and you'd see an immediate improvement rather than having to wait the normal lengthy cool-down period. The downside is that if it is the pump, you now have a full tank of gas to contend with. Once you rule this out, then you can move on to the deeper possibilities, such as those that involve checking temperature-related electronic failures. A good scan tool that can read live data would really help at that point.

Thankyou for the info, I have done oil pressure sensor, cam sensor, new MAF and I’m getting P0522 when I just replaced it. Fuel pump seems fine but at this point I think I’m just gonna send it somewhere. I can’t figure it out, never had anything run fine cold and then run like garbage when up to temp.

 

[Tonyrodz]

Thankyou for the info, I have done oil pressure sensor, cam sensor, new MAF and I’m getting P0522 when I just replaced it. Fuel pump seems fine but at this point I think I’m just gonna send it somewhere. I can’t figure it out, never had anything run fine cold and then run like garbage when up to temp.

Let us know whatever you find.

 

[Jarrett McClune]

A Tech2 will solve the mystery right quick. Where do you live? Maybe someone around you has one?

Live in Poughkeepsie ny, I’ve replaced the cam position sensor, the oil pressure sensor, the MAF, and the evap canister in the back. tomorrow I’m hoping to replace all coils and see if that makes a difference. I’ve never had an issue where it literally will not drive once it’s warmed up, it sounds terrible.

 

[swathdiver]

Yup. Something when it goes into closed loop.

If the fuel pressure is fine that would point to the MAF. Could be a couple of issues and not just one thing. Could even be the cats. You'll spend less fixing these problems if you get yourself a Tech2, if nobody around has one or an advanced scan tool at the least. Too far from me.

 

[Matahoe]

In my experience a leaking fuel pressure regulator or vacuum leak. Becasuse both are unmetered to the pcm they usually cause the most obvious running issues.

 

[SnowDrifter]

If the fuel pressure is fine that would point to the MAF. Could be a couple of issues and not just one thing. Could even be the cats. You'll spend less fixing these problems if you get yourself a Tech2, if nobody around has one or an advanced scan tool at the least. Too far from me.

While on the subject, where does one find a proper tech 2? I've poked at it but can only seem to find clones or $2k units. Is there an inbetween where I could get a legit unit at a price reasonable to the home DIYer?