Test H - Fuel Control: Notes

NOTE: For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article.

NOTE: Perform this test when Code 41, 91, 42, 92, 43, 65, 85, 86 or 93 is displayed during QUICK TESTS or when directed here by other test procedures.

NOTE: See HOW TO USE CIRCUIT TESTS, at beginning of circuit tests before performing this test. Fuel contaminated engine oil may affect Codes 41, 91, 42, or 92. If this is suspected, remove PCV valve from valve cover and repeat QUICK TEST. If problem is corrected, change engine oil and filter.

NOTE: Use this test to diagnose only the following components:

HEGO sensor
HEGO signal and ground circuit
HEGO sensor connection
Vacuum systems
Fuel injector
ECA
Electrical circuits (HEGO GND, HEGO, INJ 1-8, VPWR and SIG RTN)
NOTE: To prevent replacement of good components, be aware of the following non-EEC areas which may be the cause of driveability concerns:
Ignition coil, distributor cap or rotor
Faulty or fouled spark plugs or wires
Faulty CANP system
Distributorless Ignition System (DIS)
EGR valve and gasket
Air Filter
Fuel or engine oil contamination
Poor electrical ground
Faulty fuel pressure
Intake or exhaust system leaks
Engine below normal operating temperature

CAR - INDIVIDUAL INJECTOR RESISTANCE ⁽¹⁾

Engine

Ohms

2.3L OHC

15.0-18.0

All Others

13.0-16.0

⁽¹⁾	Resistance values are for a single injector.

CAR - INJECTOR BANK RESISTANCE

Engine	Ohms
2.3L HSC PFI	6.0-8.0
2.3L OHC PFI	7.0-9.5

TEST PIN WIRE COLOR IDENTIFICATION

Application	Wire Color
Pin 29 (Right HEGO)	Tan/Orange
Pin 43 (Left HEGO)	Tan/Red
Pin 58	Tan/Orange
Test Pin No. 59	Tan/Red

Fig 1: 2.3L OHC MA PFI (Car) Test Schematic

Fig 2: Test Schematic For All Other PFI Engines

NOTE: KOER Codes 41 and 91 are HEGO codes that indicate the system is always lean. KOER Codes 42 and 92 indicate the system is always rich. For vehicles equipped with dual HEGO's Codes 41 and 42 refer to Right (rear) HEGO sensors. Codes 91 and 92 refer to Left (front) HEGO sensors.

1) Check Fuel Pressure Turn ignition key off and wait 10 seconds. Install fuel pressure gauge. Verify that manifold vacuum supply is connected to fuel pressure regulator (if equipped). Run engine at idle and check fuel pressure. If vehicle will not start, cycle key on and off several times. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. If vehicle is a no start, cycle key on and off several times. If fuel pressure is within specification, go to next step. If pressure is not to specification, remove fuel pressure gauge. Repair electric fuel pump or fuel pressure regulator.

2) Check Fuel Pressure Check Valve With KOEO, ensure that fuel pressure remains within specification for approximately 60 seconds. If system holds pressure, but vehicle runs rough or misses, or Codes 41, 42, 91 or 92 are present, go to step 9 for sequential PFI engines, or step 4 for all others. If vehicle is a no start, go to next step. If system does not hold pressure, go to step 6 for all engine applications except sequential PFI. For sequential PFI engines, go to step 9.

3) Fuel Delivery Test Ensure fuel is of good quality. With key off, install fuel pressure gauge and pressurize fuel system as in step 1). Disconnect inertia switch. Crank engine for 5 seconds. If fuel pressure drop is greater than 5 psi after 5 seconds of cranking, the EEC-IV system is not the cause of the no start condition. Check additional no start tests in TESTS W/O CODES article. If fuel pressure drop is less than 5 psi, remove fuel pressure gauge, reconnect inertia switch, and go to next step.

4) Check Injector & Harness Resistance Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect pins for damage. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Do the following: