Engine Hesitation: ECM Modification (11-44-93)

Publication date: 1993-10-04
Reference number: 11-44-93

ENGINE HESITATION: ECM MODIFICATION

TECHNICAL SERVICE BULLETIN

Reference Number(s): 11-44-93, Date of Issue: October 4, 1993

ACCELERATION LOGIC CONTROL

Model(s): 1992-93 Subaru SVX

Group: Electrical

Bulletin No.: 11-44-93

Date: October 4, 1993

SERVICE INFORMATION

The SVX ECM has a built-in logic which controls the vehicle acceleration from a standing start. The logic controls the power during light to medium acceleration. This condition is "Normal", and no repair attempts should be made to change it. This condition is sometimes mis-diagnosed as a hesitation.

If a customer complains of a hesitation and it is not the normal condition as described above, make sure the customer is using premium fuel. A check of all basic engine functions should be performed to make sure they are all normal. If all engine functions are found to be normal, follow the procedures below.

WARNING: Before working on the ECM, remove the static charge from your body by momentarily touching an earth ground such as a cold water pipe, metal building support beam or a clean metal area of the vehicle

SERVICE PROCEDURE

Remove the ECM from the vehicle and remove the six screws securing the cover of the ECM.
NOTE: If the ECM has a ROM installed into the ROM socket, the tan resistor should be cut and/or removed. (See Service Bulletin 02-87-92).
Locate the black noise suppressor. See Fig 1 .

Fig 1: Locating the Noise Suppressor in the ECM
Wrap the noise suppressor with electrical tape.
WARNING: Safety glasses must be worn during the following procedure .
Holding the ECM upside down or on its side, grasp the black barrel shaped portion of the noise suppressor with needle nose pliers. Slowly squeeze the noise suppressor until the barrel shaped portion is crushed. Do not use a twisting motion, and be extra careful not to cut the wire which runs through the center of the suppressor. If the wire is cut or broken the ECM must be replaced.
Holding the ECM upside down, remove the tape from the noise suppressor and lightly shake the ECM to make sure all the crushed particles are out of the circuit board.
NOTE: If the ECM does not have a ROM installed into the ROM socket, do not cut the tan resistor.
Reinstall the ECM into the vehicle, and clear the memory using the select monitor.

A modified ECM will be incorporated in production beginning with 1994 model year vehicles. The modified ECM can be identified by a black dot next to the parts number label.