GASSER 48
09-19-2013, 07:58 PM
Earlier this year had problems with this fuel injection and it turned out to be the 02 sensor. It was replaced and engine ran kinda O.K. for awhile. This Hilborn system uses a Holley ECU and harness. Nothing has been changed, no new parts, no new electronics, no new repairs, nothing. This started all of a sudden a couple weeks ago when driving back home from malt shop. Engine starts O.K. and idles (800rpm) O.K. With slow increase in rpm at approx. 1400-2000 rpm engine surges badly, with spitting, popping, and sometimes backfires. This continues with increased rpm until around 3000+ and seems to smooth out. Datalog from ecu shows 02 sensor graph line going wildly up and down and the AFR (fuel) line doing the same. So engine is hunting for the correct fuel to meet the correct A/F ratio needed. Hilborn tech says it is an RFI/EMI noise issue on all sensor wire inputs. Cannot locate any sparking or grounding wires. Rechecked all harness wiring and is routed away from any high voltage (COIL, DISTR., PLUG WIRES, ALTERNATOR WIRE) sources. Installed a grounded carboard & foil shield around distributor and another shield around harness. No help. Disconnected alt wire and no change. Disconnected each sensor (coolant, tps, map, maf, & 02) and no change except on map sensor. When this was disconnected engine died. Hooked laptop and tried some old tunes and engine still surges. Turned off the closed loop system and engine still surges. Checked for any vacuum leaks and there are none. WTF???????????????????????????? Thinking this was a big $7,000. mistake.