MAZDA/FORD GF4A-EL/GF4EAT HARSH UPSHIFTS

COMPLAINT: 1993 & up, vehicles equipped with GF4A-EL transaxles, may exhibit a harsh 1-2 upshift or harsh upshift complaints when "hot", before or after overhaul. More car diagnostic tool to konw? Line pressure appears to be normal or slightly higher than normal 60-70 psi. at idle and 161-172 psi. at stall when checking in the "D" range when the vehicle is "cold." Although when the vehicle gets "hot" the pressures get irratic and or exceed the stall pressure specs, which are 175 psi. in "D" and 300 psi. in "Reverse."

CAUSE: The cause may be, a faulty Pressure Control Solenoid, a worn Boost Valve and Sleeve and/or a worn Pressure Regulator Valve bore which is part of the Rear Control Valve Body.

CORRECTION: Replace the Pressure Control Solenoid as shown in Figure 1, with Ford part number F32Z-7G136-AA or Mazda part number FU9A-21-1G1A. Inspect the Pressure Regulator Valve and the Pressure Regulator Valve bore for wear or scoring as shown in Figure 2. If the bore has "shiny" spots where the Valve rides a "New" Rear Control Valve Body can be purchased from Mazda. Inspect the Boost Valve and Boost Valve Sleeve for wear or scoring, and replace as needed with Sonnax boost valve and sleeve as shown in Figure 2.

SERVICE INFORMATION:
Pressure Control Solenoid (Ford Part No.)..............................................F32Z-7G136-AA
Pressure Control Solenoid (Mazda Part No.).............................................FU9A-21-1G1A
Rear Control Valve Body (Mazda Part No.)................................................FU9C-21-115G
   NOTE: This is a new casting with no valves in it.
Boost Valve and Sleeve (Sonnax Part No.)........................................................74846-01K
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