2000 Chevy S-10 major hesitation

chevy262ss · Posted at Thu Jul 02, 2009 4:42 pm

Engine Performance problem
2000 Chevy S-10 6 cyl Four Wheel Drive Automatic 112939 miles

i have a 2000 s10 with major issues, it seems to hesitate very badly, anything over 1/3 throttle is useless. the truck threw up 2 codes, p0101 and p0440, a maf code and a evap code, every time they come on at the same time. i have noticed while watching the scan tool my maf moves in relation to engine rpms which seems good, tps test out fine and map seems to be working good, only thing that looks suspicious to me is the ignition advance, at idle its close to thirty but as i increase throttle with it under load it tends to drop around 10 or below, i assumed advance would go up with rpms, not down. truck has new fuel pump with good pressure, and a fresh tuneup, it has been running like this for a long time, i just acquired the truck. sorry for the long post but im starting to get lost on this, im not sure what is common between the 2 codes, and the whole ignition advance, not sure if this is my culprit and what would be causing it. knock sensor maybe. well thanks in advance.

rasmataz · Posted at Thu Jul 02, 2009 5:12 pm

Ignition advance -KS might be retarding the timing-check it

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires

chevy262ss · Posted at Fri Jul 03, 2009 2:11 am

the truck has 52lbs fuel pressure, and new plugs wires cap and rotor, new coil, tested with known good map, maf is clean. i thought about the injectors but my scan tool is not throwing any misfire codes which kind of confuses me. thanks for your reply, im gonna start messing with it again today.