Rough Running Engine

[Hermy13]

Ok i have a rebuilt 350 in my 98 chevy 1/2 ton. it has aprox 1000 miles on
The problem im seeming to have is at low rpm it is surging and sputtering. we have checked plugs wires cap rotor timing fuel system ect we are out of ideas so if any of you got some idea feel free to chime in. Thanks

 

[1985_K5_Silverado]

Is it tossing out any trouble codes?

 

[Leper]

Did you set the timing correctly? If not, the computer will try to compensate for your adjustments.

 

[Hermy13]

There is no codes commign up. the timing was set right at 0 with the scanner how all data says to.

 

[1985_K5_Silverado]

Does the surging/sputtering at low rpm happen after a cold start and when warmed up? In gear & under load as well as out of gear? At what approx rpm does it smooth out?

Have you stuck a vacuum gauge on it, and if so, what is the gauge showing when it's surging/sputtering?

I assume all the plugs all look normal? All cyls have normal compression?

 

[1985_K5_Silverado]

Any chance your EGR valve is open at low rpm (when it shouldn't be)?

 

[Hermy13]

it is rough cold or warm it doesnt seem to matter. in gear sitting at a stop light seems to be the worst. No havnt hooked gauge to it will check it out.