Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1988 Merkur XR4Ti AutomaticFACTORY OEM SERVICE PROCEDURE
Circuit Test SS - System Check
- ISC Check. Attempt to start engine at part throttle. If engine runs only at part throttle, go to CIRCUIT TEST Z , step 3). If engine does not run, go to step 3).
- MAP Check. Turn key off and disconnect MAP sensor. Connect MAP tester between harness and MAP sensor. Connect banana plugs of tester into DVOM and set DVOM on 20-volt scale. Turn key on and measure sensor output voltage while cranking engine. If DVOM reading does not decrease from specified range, go to CIRCUIT TEST H
, step 13). If DVOM reading decreases from specified range, go to next step.MAP VOLTAGE OUTPUT
Elevation (Ft.) Voltage Output (Volts) 0 1.55-1.63 1000 1.52-1.60 2000 1.49-1.57 3000 1.46-1.54 4000 1.43-1.51 5000 1.40-1.48 6000 1.37-1.45 7000 1.35-1.43 - EGR Check. Disconnect and plug vacuum hose at EGR valve. Ensure that EGR valve is closed. Attempt to start vehicle. If vehicle runs, go to CIRCUIT TEST W , step 1).
Factory Service Tools
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.