Engine Controls - Low RPM, No Start, Runs Poorly

Article No.
03-21-23

10/06/03

DRIVEABILITY - LOW RPM - NO START - RUNS
POORLY - STALL - 7.3L DIT ENGINE

FORD:
1994-1997 F SUPER DUTY, F-250, F-350
1995-1997 E-350

Article 97-6-18 is being republished with updates as part of a consolidated 7.3L diagnostic aid booklet.

ISSUE

The 7.3L Direct Injection Turbo (DIT) engines are built with 0.1016-0.8128 mm (0.0040-0.032") clearance between the Camshaft Position (CMP) Sensor and the trigger wheel. At approximately 1.016 mm (0.040") clearance, the sensor will fail to synchronize and result in a no run condition. Improper CMP clearance can be seen in the following six (6) symptoms:

^ 1) Fault codes - incorrect synchronization count

^ 2) Low RPM - fails to achieve rated speed for 2-3 minutes after extended cold soak

^ 3) No start - after extended cold soak

^ 4) Runs poorly cold - engine runs OK warm

^ 5) Stall on deceleration - more pronounced cold

^ 6) Starts, runs cold, dies warm, will not restart until cool

ACTION

Install a shim between the CMP sensor and the front engine cover. The shim will allow the correct clearance which should reduce the possibility of concerns. Refer to the following Service Procedure for details.

SERVICE PROCEDURE

1. Perform normal DIT Powerstroke diagnostics. If no other problems are found, proceed with this TSB article.

2. Remove CMP sensor and inspect for signs of contact with the pulse wheel. Make sure the holes on the end are filled with epoxy and inspect the connector mating cavity for signs of oil contamination. If there are any signs of contact, contamination, or the holes are not filled, replace the CMP Sensor (F6TZ-12K073-A).

3. Repair symptoms 1) - 5) as follows: install a 0.254 mm (0.010") shim under the CMP sensor. If symptoms persist, increase the shim thickness to 0.508 mm (0.020") Shim (F7TZ-1 2J072-AA).

NOTE
SOME ENGINES BETWEEN SERIAL NUMBERS 388840 AND 410010 HAVE BEEN BUILT WITH EXCESSIVE AMOUNTS OF TRIGGER WHEEL RUNOUT. RUNOUT OF THE TRIGGER WHEEL GREATER THAN 0.508 mm (0.020") MIGHT NOT BE RESOLVED WITH A SHIM. THE ADDITIONAL CLEARANCE CAN PUT TOTAL CLEARANCE ABOVE 1.016 mm (0.040") AND CAUSE FAILURE TO SYNCHRONIZE.

4. If symptom 6) occurs and trigger wheel runout is greater than 0.508 mm (0.020"), try a 0.254 mm (0.010") shim. If the concern is unresolved, replace the Camshaft Assembly (F4TZ-6250-A). Refer to the appropriate model/year Service Manual, Section 03-01C, for camshaft assembly replacement procedure.





PARTS BLOCK

OTHER APPLICABLE ARTICLES: NONE
SUPERSEDES: 97-6-18
WARRANTY STATUS: INFORMATION ONLY





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