Diesel Engine - Supplemental Diagnostic Tips
Article No. PERFORMANCE POOR - 6.9L DIESEL - SUPPLEMENTAL SERVICE DIAGNOSTIC TIPS
87-10-21
FORD - LIGHT TRUCK: 1987 E SERIES, F SERIES
ISSUE: Supplemental Service Diagnostic Tips have been developed to make sure of accurate diagnosis of poor performance concerns on the 6.9L diesel engine.
ACTION: To diagnose the cause of poor 6.9L engine performance, use the following supplemental service procedures.
The information in this article is to be used with the 1987 Engine/Emission Diagnosis Shop Manual, Volume H, and with Engine Performance Chart (Form FPS-8433-C) 6.9L (420 CID) Diesel Engine Diagnostic Guide. Steps 1 through 6 of Form FPS- 8433-C are to be completed and recorded before starting this procedure. (This includes correction of any concerns found in the first six steps.)
Figure 19 - Article 87-10-21:
1. Check accelerator linkage, Figure 19. Throttle lever MUST contact full throttle stop when accelerator pedal is fully depressed. If the full throttle stop is not reached, or if the accelerator pedal interferes with floor carpet/mat as the pedal is moved towards wide open throttle, install the new (E7TZ-9725-A) pedal which will provide 3/8 inch additional pedal clearance. The engine cannot produce maximum power or RPM if full throttle is not achieved. Record results in Step 8 of Form FPS-8433-C.
Figure 20 - Article 87-10-21:
Figure 21 - Article 87-10-21:
2. Check adjustment of transmission kickdown linkage (automatic transmission only). Refer to Figures 20 and 21. Adjust kickdown rod as follows.
a. Attach 6 lb. weight to transmission kickdown lever.
b. Rotate throttle to wide open position.
c. Insert a 0.060 +/- .005 inch spacer between throttle lever and adjusting screw on fuel injection pump kickdown lever. If less than .060 inch clearance, back off adjusting screw.
d. Rotate adjusting screw until contact is made between screw and the 0.060 inch spacer.
e. Remove the 0.060 inch spacer.
f. Check gap after spacer is removed. A gap of 0.010 to 0.070 inch is acceptable.
g. Remove the 6 lb. weight.
If kickdown linkage is out of adjustment, transmission up-shifting at low engine RPM can result. This would not allow maximum engine RPM and power. Also, transmission may kickdown too early, or have delayed up-shifts, if misadjusted.
3. Check adjustment of Vacuum Regulator Valve (VRV) (automatic transmissions only). Refer to Figures 22 and 23. On a 6.9L diesel engineequipped truck with C6 automatic transmission, a VRV provides a vacuum signal which is proportional to the throttle position, to the transmission vacuum diaphragm. To check the VRV for proper operation and adjustment, the engine must not be running.
Figure 22 - Article 87-10-21:
a. Disconnect the two-port vacuum connector from the VRV located on the left side of fuel injection pump, Figure 22.
b. Remove throttle cable from throttle lever on right side of fuel injection pump.
c. Remove throttle return spring. Install end of spring over throttle lever ball stud and other end over throttle cable support bracket.
d. Attach a vacuum pump with gauge to upper port of VRV (vacuum supply side).
e. Attach a vacuum gauge to lower port of VRV (labeled TRANS on VRV).
f. Apply 20 inches minimum of vacuum to VRV and maintain. It will be necessary to pump vacuum up as it bleeds off.
CYCLE THROTTLE LEVER FIVE (5) TIMES FROM IDLE TO WIDE OPEN THROTTLE (WOT) WITH VACUUM APPLIED.
Figure 23 - Article 87-10-21:
Insert gauge block, T83T-7B200-AH (0.515 inch), between pump boss and throttle wide-open stop, Figure 23. The throttle return spring, as re-positioned in Step C. above, will hold throttle lever stop against gauge block.
THE VACUUM GAUGE ATTACHED TO LOWER PORT OF THE VRV SHOULD INDICATE 6-8 INCHES VACUUM. IF VACUUM READING IS WRONG, ADJUST VRV TO OBTAIN READING OF SEVEN (7) INCHES OF VACUUM.
g. To adjust, loosen the two (2) screws that attach VRV to fuel injection pump, Figure 22. Rotate VRV until proper vacuum is obtained. When you get proper vacuum reading, tighten the two (2) screws to 75-90 in.lbs. (8-10.5 N-m). If VRV cannot be adjuted to get proper vacuum, replace the VRV and repeat this procedure starting at Step D.
h. Remove gauge block.
i. Reattach throttle return spring and throttle cable.
j. Apply 20 inches of vacuum to the VRV and WHILE MAINTAINING VACUUM, CYCLE THROTTLE LEVER FROM IDLE TO WOT FIVE (5) TIMES. The vacuum gauge must indicate at least 13 inches with throttle at idle position. If vacuum gauge indicates less than 13 inches, the VRV must be replaced and the new VRV adjusted per the above procedure.
k. After making the check or adjustment, remove vacuum pump and gauge from VRV and reattach vacuum connector.
l. Start engine. Check throttle operation and check transmission shifts.
Correct VRV usage is necessary to be sure of proper vehicle and transmission performance. The current VRV usage (service) is as follows:
1983-86 model years E5TZ-7B200-A
(green VRV cam)
1987 model year E7TZ-7B200-A
(yellow VRV cam)
The wrong adjustment, or the wrong VRV, can result in delayed or harsh shifts.
4. Remove noise choke from air cleaner tray assembly (late 1985 through 1987 model year vehicles only).
a. Remove air cleaner assembly from vehicle.
b. To avoid damage to alignment tabs or water drain tube (if equipped), place the tray only, open side up, on two supports (use 2 x 4 boards).
c. Inside the air cleaner are six (6) spot welds which fasten the choke to tray bottom. Remove the spot welds without causing through holes in the tray. Center punch spot welds. Using a spot weld cutter/remover, remove the spot weld.
d. After you make sure each spot weld is removed, turn air cleaner tray over and place tray lip on two (2) supports to protect internal baffle, (if so equipped).
e. Using a board and hammer, drive out the choke and wing bolt guide assembly.
f. Deburr all holes and sharp edges.
g. If there is a through hole in the tray at any of the spot welds, clean those spot weld areas of any grime and/or paint on underside of tray. Use a putty-type epoxy to seal the hole(s) by putting epoxy on underside of tray. Make sure seal is larger than the hole to guard against ingestion into the air cleaner and engine. Let the epoxy cure.
h. Clean the entire tray to be sure metal filings and shavings are removed.
i. Spray unpainted surfaces with enamel base, black paint.
j. Reinstall air cleaner assembly.
The noise choke in the air cleaner tray may cause a power reduction in heavy trailer tow applications. Removal of the choke may not cause a noticeable increase in performance in lightly loaded vehicles (example, 0-50 mph/0- 80 km/h performance times on empty trucks may not improve).
5. Make sure the cooling fan clutch operates correctly (check for premature or constant engagement of fan clutch). Only fan clutches supplied by Schwitzer and installed on vehicles prior to a December, 1986 build date (as shown on the vehicle ID plate) are suspected of this malfunction. Schwitzer fan clutches were used on all E Series and some F Series (Ontario Truck and Norfolk Assembly Plants only) during all of the 1986 and part of 1987 model years. The Schwitzer fan clutch can be identified by a gold-color ring of metal around the edge of the fan clutch. If a clutch is suspect because of a
continuous noise, the unit should be removed and checked for inner bearing race retention using the following procedure.
a. Clean shaft and bearing area at rear of clutch.
b. Mark black shaft and bearing race (small silver ring at base of shaft) with a yellow grease pencil).
c. Hold clutch body down and hold fan.
d. Turn clutch shaft hex nut at least 10 complete revolutions while observing bearing race.
e. If the mark on bearing race has not moved relative to the mark on the shaft, the unit is okay.
f. If not okay, install an Eaton fan clutch (E5TZ-8A616-C) and return the faulty unit to the Warranty Parts Return Center.
NOTE: It is normal for fan clutch to engage on fully-loaded trucks, on long grades, and/or during very hot weather. See Shop Manual, Section 27-09 for removal and installation procedures. The cooling fan uses an increased amount of engine horsepower with fan clutch engaged. This loss of power is unavoidable if fan clutch is working normally.
6. Record any repairs or adjustments made in Steps 2 through 5 above in the comment section on Form FPS-8433C.
7. Complete Step 7 and Steps 9 through 11 of the 6.9L Diesel Engine Diagnostic Guide, record on FPS-8433C. This includes correction of any concerns found during these steps.
8. Road test vehicle doing aminimum of four (4) in-gear, wide-open throttle, acceleration tests.
NOTE: ALL ROAD TESTS MUST BE CONDUCTED IN ACCORDANCE WITH ALL STATE AND LOCAL LAWS, INCLUDING SPEED LIMITS.
Do the in-gear WOT acceleration tests as follows using a second person to observe and time.
a. Weigh vehicle with driver and observer onboard. (Retain scale ticket and attach copies to warranty claim and FPS-8433C.)
b. Measure vehicle frontal area if vehicle is other than an empty standard pickup, van or Club Wagon. (Measure maximum vehicle width and multiply times the maximum vehicle height on any truck equipped with an aftermarket second body, slide-incamper, box, topper, or anything else that increases frontal area over and above the standard production vehicle. Record vehicle frontal area in the "Chassis Style" box on top of FPS-8433C.
NOTE: Vehicle performance decreases with increased frontal area. VEHICLE AND/OR TRAILER FRONTAL AREA GREATER THAN 60 SQ. FT. ARE NOT RECOMMENDED BY FORD AND WILL RESULT IN POOR VEHICLE PERFORMANCE.
c. Check speedometer accuracy by driving and timing the truck over a measured mile. Refer to the Ford Truck Master Parts Catalog for proper speedometer gears to use for various rear axle ratio and tire size combinations. Speedometer inaccuracy can cause you to think there is poor performance. The use of oversize aftermarket tires will result in speedometer inaccuracy.
OVERSIZE TIRES WILL ALSO RESULT IN REDUCED VEHICLE PERFORMANCE DUE TO THE CHANGE IN EFFECTIVE VEHICLE AXLE RATIO WHICH REDUCES THE DRIVE EFFORT AVAILABLE AT THE GROUND. IF THE VEHICLE IS EQUIPPED WITH OVERSIZE TIRES, THEY MUST BE RETURNED TO STOCK SIZE AND SPEEDOMETER MUST BE ACCURATE BEFORE CONTINUING THIS TEST.
If this cannot be done, return truck to customer with the oversize tires as the probable cause of poor performance.
d. Road test vehicle to warm-up engine.
NOTE: Engine temperature must be in normal range.
e. Automatic Transmission Vehicles ONLY:
Check kickdown adjustment per Step 2. Do several WOT accelerations (D-range). Record the 1-2 and 2-3 upshift RPM and/or mph.
CHART A1983 THROUGH 1985 LIGHT TRUCKS6.9L DIESEL ENGINE/C6 TRANSMISSION/3.07 OR 3.08 AXLE RATIO:
CHART B1983 THROUGH 1987 LIGHT TRUCKS6.9L DIESEL ENGINE/C6 TRANSMISSION/3.54 OR 3.55 AXLE RATIO:
CHART C1983 THROUGH 1987 LIGHT TRUCKS6.9L DIESEL ENGINE/C6 TRANSMISSION/4.10 AXLE RATIO:
CHART D1983 THROUGH 1985 LIGHT TRUCKS6.9L DIESEL ENGINE/M4 (CLOSE RATIO) TRANSMISSION/3.07 OR 3.08 AXLE RATIO:
CHART E1983 THROUGH 1987 LIGHT TRUCKS6.9L DIESEL ENGINE/M4 (CLOSE RATIO) TRANSMISSION/3.54 OR 3.55 AXLE RATIO:
CHART F1983 THROUGH 1987 LIGHT TRUCKS6.9L DIESEL ENGINE/M4 (CLOSE RATIO) TRANSMISSION/4.10 AXLE RATIO:
CHART G1983 THROUGH 1985 LIGHT TRUCKS6.9L DIESEL ENGINE/M4 (WIDE RATIO) TRANSMISSION/3.07 OR 3.08 AXLE RATIO:
CHART H1983 THROUGH 1987 LIGHT TRUCKS6.9L DIESEL ENGINE/M4 (WIDE RATIO) TRANSMISSION /3.54 OR 3.55 AXLE RATIO:
CHART J1983 THROUGH 1987 LIGHT TRUCKS6.9L DIESEL ENGINE/M4 (WIDE RATIO) TRANSMISSION/4.10 AXLE RATIO:
f. All Vehicles: Do four (4) WOT accelerations from a running start in 3rd gear on manual transmission vehicles, or with the shift indicator in 2nd gear on automatic transmission vehicles. These accelerations should be done on level ground running two (2) tests in each direction. Start the stopwatch and floor the accelerator at the same time. Start the test at the "starting speed" and accelerate to "end speed" given in the appropriate chart on pages 9 through 17 of this TSB. Rerun any test for which time differs greatly from other test runs. When four (4) good tests have been finished, average the results.
g. Compare the average with "acceptable performance" numbers given in the appropriate chart. Use the chart for the transmission, axle ratio, and tire combination that matches the vehicle equipment. Use only the vehicle weight and frontal area from Items a and b above. Enter vehicle weight across bottom of chart. Go down left side of chart to frontal area equal to frontal area of vehicle.
NOTE: Frontal area is labeled for standard trucks (F-250 4x2 pickup). The number where vehicle weight and frontal area meet is the "acceptable performance" for vehicle being tested. Record both the average of the vehicle test runs and the "acceptable performance" numbers in the comment box on FPS-8433C.
h. If test result is less than "acceptable performance" number, see Steps 10 through 12. If test result is greater than "acceptable performance" number, proceed to Step 9.
9. Do this Step only if directed to by Step 8. Complete Step 12 of the 6.9L Diesel Engine Diagnostic Guide (Form FPS-8433C). If crankcase pressure is within specification, replace fuel injection pump. Refer to Shop Manual Section 22-08-36.
WARRANTY CLAIMS FOR THE INJECTION PUMP WILL NOT BE ACCEPTED UNLESS ALL TAMPER-RESISTANT SEALS ARE INTACT AND THE COMPLETED ENGINE PERFORMANCE CHART, FPS-8433C, IS SUBMITTED WITH THE RETURNED PART. (See Steps 10 through 12.)
10. Check automatic transmission upshift speeds. If automatic transmission upshift speeds recorded in Step 8e. are on the low end (2700-2900 RPM) of the 1-2 and 2-3 upshift RPM band (2700-3400 RPM), refer to TSB Article Number 85-21-17. This TSB is NOT needed on vehicles built after September, 1985. Installation of the upshift kit (E5TZ-7A288-A) improves the early upshift condition by tightening the tolerance band resulting in a 3000 RPM minimum 1-2 and 2-3 wide open throttle shift. This slightly improves vehicle performance with a 2-4 mph (3-6 km/h) increase in kickdown and wide open throttle shift points.
NOTE: On vehicles equipped with the 3.07 axle ratio, it is not recommended to use this kit to resolve towing concerns. Low power towing concerns may indicate the wrong axle ratio for the truck's application.
11. Check manual transmission gear ratios for the customer's application. Two different sets of gear ratios have been used in the T19 manual transmissions behind the 6.9L diesel engine. The 1983 model year through March, 1984 production used a wide ratio gear set (5.11, 3.03, 1.79 and 1.00). This wide ratio gear set resulted in performance concerns on trailer tow vehicles with regards to the wide split between third and fourth gears. The vehicle could be accelerated in third gear up to 3400 engine RPM shifted to fourth gear and lose speed forcing a downshift back to third gear. TSB Article Number 84-4-29 outlines changes from a wide ratio to a close ratio gear set. The vehicles produced after March, 1984 use a close ratio gear (4.02, 2.41, 1.41, 1.00).
This close ratio gear set improved vehicle performance on the highway with a trailer or heavy load. Starting gradability is reduced. Vehicles used as wreckers or other start-up applications, but not used for highway trailer towing and built after March, 1984, can be changed to a wide ratio gear set.
12. Check rear axle ratio for the customer's application. Three different axle ratios have been used on vehicles equipped with the 6.9L diesel engine. The 3.07 axle ratio is used for vehicles at empty to light loads or light trailer towing. The 3.54/3.55 axle ratios are used for vehicles used at empty to moderate loads or for occasional or light trailer towing (Max. GCW 12,000 lbs.). The 4.10 axle ratio is recommended for trailer towing, performance intensive and high altitude applications (Max. GCW 14,000 lbs.).
NOTE: Changes in axle ratio to improve vehicle performance may reduce fuel economy.
Other things that may add to the customer's belief of poor engine performance are: 1) dual versus single-rear wheels causing added rolling resistance and increased wind resistance of the vehicle with dual rear wheels, and 2) four-wheel versus twowheel drive vehicles causing loss of horsepower because of the additional drivetrain components, additional rolling resistance, weight, and increased frontal area of the four-wheel drive vehicle, 3) auxiliary equipment such as PTO operated equipment, larger alternators, air conditioning systems that are in operation during vehicle acceleration causing reduced performance, and 4) added coolers or equipment mounted in front of the radiator reduce the cooling system's efficiency resulting in increased cooling fan loads which reduce vehicle performance.
USE OF CHARTS
^ For use on 1983-85 models with 3.07 or 3.08 axle ratios and 1983-87 models with 3.54, 3.55, or 4.10 axle ratios:
Chart Transmission Axle Ratio
A C6 3.07/3.08
B C6 3.54/3.55
C C6 4.10
D M4 (close ratio) 3.07/3.08
E M4 (close ratio) 3.54/3.55
F M4 (close ratio) 4.10
G M4 (wide ratio) 3.07/3.08
H M4 (wide ratio) 3.54/3.55
J M4 (wide ratio) 4.10
^ Charts must not be used at altitudes higher than 2000 feet (50.8 meters) above sea level or 95~ (35~C) ambient temperatures. The 6.9L diesel engine loses torque at a rate of 10 ft.lbs. per 1000 feet (25.4 meters) above sea level. This loss will affect vehicle performance. The charts are to be used on 6.9L sea level calibrations only. No high altitude calibration charts will be published because of low volume and vehicle complexity requirements for use in high altitude applications.
^ Do not test with trailer. Trailers represent both an increased frontal area and rolling load and are not covered in the charts.
^ Vehicle that equals or is less than the time noted in the charts meets acceptable performance.
^ Charts cover vehicle weights only up to Ford Motor Company's maximum recommendations for a particular chassis and axle ratio. Frontal areas in excess of the Company's recommendations are included only because it is recognized that the frontal area of a complaint vehicle cannot always be reduced for testing. Operating the vehicle with a frontal area in excess of the Company's recommendation will affect the vehicle's performance, fuel economy and durability.
PART NUMBER PART NAME CLASS
E7TZ-9725-A Accelerator Pedal B
E5TZ-7B200-A Vacuum Regulator Valve B
(Green)
E7TZ-7B200-A Vacuum Regulator Valve B
(Yellow)
E5TZ-8A616-C Eaton Fan Clutch BM
OTHER APPLICABLE ARTICLES: 86-2-26, 85-21-17, 85-1-19, 84-4-29
WARRANTY STATUS: Reimbursable within the provisions of the Warranty and Policy Manual
OPERATION: SP871021A - Steps 1 through 6 of the Diesel Engine Diagnostic Guide.
TIME: 0.9 Hr. - F Series (Single Fuel Tank)
1.2 Hrs. - F Series (Dual Fuel Tanks)
0.8 Hr. - E Series (Single Fuel Tank)
1.2 Hrs. - E Series (Dual Fuel Tanks)
OPERATION: SP871021B - Step 1 (includes replace accelerator pedal)
TIME: 0.4 Hr. - F Series
0.5 Hr. - E Series
OPERATION: SP871021C - Step 2
TIME: 0.3 Hr. - F Series/E Series
OPERATION: SP871021D - Step 3 (Includes road test. Does not include time to replace VRV)
TIME: 0.7 Hr. - F Series/ E Series
OPERATION: SP871021E - Step 4
TIME: 0.6 Hr. - F Series/E Series
OPERATION: SP871021F - Step 5
TIME: 0.5 Hr. - F Series/E Series
OPERATION: SP871021G - Step 7
TIME: 2.8 Hrs. - F Series (Single Fuel Tank)
3.1 Hrs. - F Series (Dual Fuel Tanks)
3.1 Hrs. - E Series (Single Fuel Tank)
3.3 Hrs. - E Series (Dual Fuel Tanks)
OPERATION: SP871021H - Step 8 (Does not include time to replace speedometer gear)
TIME: 1.4 Hrs. - F Series/E Series
OPERATION: SP871021J - Step 9 (includes reset timing)
TIME: 2.2 Hrs. - F Series
3.9 Hrs. - E Series
OPERATION: SP871021K - Step 10 (includes road test)
TIME: 1.7 Hrs. - F Series/E Series
DLR. CODING: Basic Part No. 6009 - Code: 53