2005 suburban 5.3 surging on highway under load

[afpj]

What are fuel trims looking like at idle and at 1500-2000rpm? That might help with intake leak diagnosis

 

[Sstevieboy0208]

oh, no you mentioned coolant loss and smoke, I only used it myself for a mysterious internal coolant leak, I wouldn't put anything in for oil leaks just get them fixed when you can adding a little oil as needed isn't very costly.

Okay and the smoke on stattup. Valve cover is 3 months old but only when it's cold out.

 

[Doubeleive]

Okay and the smoke on stattup. Valve cover is 3 months old but only when it's cold out.

what color is the smoke? if it is a light grey color and only last's a few minutes that is normal from condensation.

 

[Sstevieboy0208]

what color is the smoke? if it is a light grey color and only last's a few minutes that is normal from condensation.

It is light gray and it's like a puff and stops. Lasts maybe 15 to 30 seconds

 

[Doubeleive]

It is light gray and it's like a puff and stops. Lasts maybe 15 to 30 seconds

that could be oil getting past the seals in the motor after it has sat, that would coincide with some oil loss but if you have a leaking rear main or other leaks it's really hard to say how much oil it's using until all the leaks are fixed, I have had vehicles that did that and didn't have any other leaks and they would burn like a quart every 1000 miles or so, it was bearable a few quarts of oil use per year way is less than a engine rebuild

 

[Sstevieboy0208]

that could be oil getting past the seals in the motor after it has sat, that would coincide with some oil loss but if you have a leaking rear main or other leaks it's really hard to say how much oil it's using until all the leaks are fixed, I have had vehicles that did that and didn't have any other leaks and they would burn like a quart every 1000 miles or so, it was bearable a few quarts of oil use per year way is less than a engine rebuild

I've been looking into blue devil and was going to give it a try. And as far as the smoke it's like you said could be condensation. But since I put STP stop leak and smoke in it that's when it started. So considering blue devil since i have a bottle of it already but not sure if I must get oil change first or just add it in there

 

[Doubeleive]

I've been looking into blue devil and was going to give it a try. And as far as the smoke it's like you said could be condensation. But since I put STP stop leak and smoke in it that's when it started. So considering blue devil since i have a bottle of it already but not sure if I must get oil change first or just add it in there

they sell different products, just be sure to follow there directions properly for it to work right, they have videos on there website

 

[Sstevieboy0208]

they sell different products, just be sure to follow there directions properly for it to work right, they have videos on there website

Okay. Thank you. I was more curious if I need to change oil before adding it or after

 

[PNWYukon]

If an engine is not getting enough fuel (this is called “running lean”), due to fuel pressure (regulated by the fuel pump and regulator), restricted fuel injectors, a vacuum leak or really anything that throws off the fuel mixture going in to the engine, this can cause the surge.

Vacuum leaks can be tough to find. Maybe you know someone with a smoke tester?

I know my rig doesn't have an external fuel filter, does yours?

Try to get live data about fuel pressure and trims.

 

[Doubeleive]

If an engine is not getting enough fuel (this is called “running lean”), due to fuel pressure (regulated by the fuel pump and regulator), restricted fuel injectors, a vacuum leak or really anything that throws off the fuel mixture going in to the engine, this can cause the surge.

Vacuum leaks can be tough to find. Maybe you know someone with a smoke tester?

I know my rig doesn't have an external fuel filter, does yours?

Try to get live data about fuel pressure and trims.

they stopped using the inline fuel filters I think in 2002-2003, I can't remember I think my 03 silverado had one, the 04 suburban did not