The Lucas 14CU 'hot wire' airmass system ECU has proved to be more reliable than the earlier 'moving flap' airflow system 4CU ECU. Please click here for ECU photo. A common ECU problem we see is loss of 1 (or both) injector banks (usually following work in engine compartment) This failure is relatively easy to diagnose (check for injector pulses).
Early 3.9 ECU type number PRC7081 (superceded by PRC9061) develops a misfire at 2,800rpm (most noticeable at motorway speeds when overtaking). We now have a fix for this.
14CU ECUs as a group can suffer from intermittent running problems - such as running rich or cutting out for short periods - which are very difficult to diagnose so when there are vehicle problems we STRONGLY recommend road testing with a substitute before condemning your ECU.
Air mass meters are also causing running problems as vehicles age. Again, because diagnosis is so difficult, we STRONGLY recommend road testing road with a substitute before condemning air mass meter.
IN ALL CASES OF HOTWIRE system 3.5/3.9 vehicles (from 1990) WITH IDLING OR RUNNING PROBLEMS REFER TO THIS DIAGNOSTIC CHECKLIST BEFORE PROCEEDING.
We have a repair and rebuild service for these ECUs - Please click here for full address and repair quote form.
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