Sputtering over 40MPH - 1999 Chevy Suburban


#1

My 1999 Chevy Suburban K1500 5.7 L Gas Engine sputters momentarily when I’m giving it a little gas when traveling at 40+ MPH. It only seems to happen when I go from coasting to just slightly pressing the accelerator to maintain speed. Pressing the accelerator down further makes the sputtering go away, but as soon as I take my foot off the gas and then slightly press on it, it sputters again. Any thoughts?


#2

Look at the Throttle Position Sensor because that sensor provides information to the computer to enrichen the mixture during transitions. You could check the resistance across the potentiometer to see if it matches specifications and if the wiper reads correctly at various settings. You will need to use a analog meter to check to see if the TPS is reading continuously from idle stop to just off idle. Also make sure that the TPS is adjusted to specifications.

Also I would check the vacuum hoses, vacuum motors, and intake manifold for possible leaks that would cause lean conditions on ‘open loop’ fuel calculation.

Hope that helps.