Hi, I have a 1985, S10, 2.8L, carb, California emission truck. The truck mileage is low, maintenanced and in good condition. I'm hoping the information below will make sense to someone because the timing problem has me stumped???
SYMPTOMS #1: (timing set buy ear) starting = ok idling = feels a little ruff (sounds fat) power = ok timing advance = ok (4pin connected) timing check is way off per UDW label (maybe 45d adc) & OBD jumper makes the TIMING MARK FLOAT (+20d every rev) 360d cylinder #6 lower end knock's real bad when cold. (any load/rpm) & engine knock almost gone when hot. (any load/rpm) & engine does not knock when OBD jumpered (check off)
SYMPTOMS #2: (timing set per emission label UDW) starting = low cranking RPM (incorrect timing) idling = ok? (felt normal but extreme knock) power = ok? (felt normal but extreme knock) timing advance = ok (4pin connected) timing check is correct per UDW label lower end knock's real bad at any rpm, load or temp.
TROUBLE SHOOTING: mileage = 130,000 (engine/trans 30,000 carb/dist 10,000) maintenance = ok drive test = ok (excluding the knock sound) OBD = ok (12) via blink code ignition timing = POSESSED BY AILEN'S ignition distrib = ok (repaired a LOOSE GROUND) oil pressure = ok (dashboard gauge) engine/emission controls = #2 passed function tests (geeze that took forever) vacuum = no leaks, passed function tests (geeze that took forever) top end = everything under the valve covers looked ok (and no sludge) bottom end = not checked compression = not checked engine knock = noise is different than bearing or valve train typically sound engine knock = gone if no spark to #6 engine knock = gone if OBD jumperd engine knock = worse with timing at UDW timing chain = distributor / crank slop seem ok knock sensor = n/a (so im told anyway)
Any ideas would be great.
Thanks Danny