Installation manual

- 15 - Ford Racing Technical Support (800)FORD-788
M-12071-A50
REVISION 2
(Troubleshooting - Continued)
11.4 Verify that you have connected the black ground wire (Page 6, Connector #17)
DIRECTLY to the negative side of the battery. Do NOT
attach this connection to
any other ground source. The entire EFI system is dependent upon this ground.
Be sure to solder any splices that may have been required if this connection
needed to be lengthened.
11.5 Inspect the engine for vacuum leaks. Vacuum leaks will allow air to enter the
engine without being monitored by the mass air meter, which will cause the PCM
to ‘think’ that the engine is receiving less air than it actually is, causing a lean
condition.
11.6 Verify that you are using a quality Mass Air Flow meter. This sensor is the single
most important sensor in the entire EFI system and is a common culprit of idle
surge and low speed drivability problems. Ford Racing offers MAF meters that
exceed OEM quality; refer to section 3.3 (on page 3) for more information.
11.7 Verify proper fuel pressure within the system. Ford EFI systems normally require
39-42 psi at the fuel rail. An IN-TANK fuel pump is highly recommended as this
will help to eliminate the potential for cavitation (vapor bubbles) in the fuel supply
line. If you still choose to use an externally mounted fuel pump, you should be
ABSOLUTELY
CERTAIN that it is gravity fed, meaning the fuel pump does not
have to ‘pull’ the fuel to it. If the fuel pump creates a vacuum in the inlet of the
fuel pump, the fuel can easily ‘flash’ to a vapor, creating tiny vapor bubbles
within the inlet of the fuel pump. When these vapor bubbles pass through the
pump to the ‘high pressure’ side, they do not go away; they are merely
compressed. Once these vapor bubble are expelled through the fuel injectors,
they are no longer under pressure and they will expand, displacing the fuel that
is needed by the engine, and generally causing a lean condition. This problem is
commonly characterized by becoming worse as the engine warms, and/or during
warm weather which usually consists driving over hot pavement which reflects
heat towards the fuel tank.
11.8 Perform a diagnostic test via the Self Test Conn
ector. If you do not have an EFI
Scan Tool available, it is also possible to perform this test using a simple jumper
wire at the Self Test Connector. With the ignition switch in the OFF position,
hook up a jumper wire from the GY/RD wire (359) in the 6-pin connector to the
W/P wire (209) in the 1-pin connector. When the key is turned to the RUN
position, after about 15 seconds, the 'Check Engine' light will begin to flash
indicating which codes are present in the PCM.
Once all codes are reported, the codes will repeat
once again. These are the Key On Engine Off
(KOEO) codes. Wait approximately 10 seconds
after the KOEO test, and there will be a single
flash, followed by another set of DTC codes which
will follow. These are the 'Continuous' codes.