Car has 155K miles. Engine seems solid but hesitates after long stoplights and sluggish on acceleration. Not being able to start after an hours drive has gotten my attention. The car has been run on long trips and never did that. The plugs,wires,cap and rotor are good. The VCM code must have identified the problem area. Where is a good place to start without going over the whole fuel system. Competant replies will be appreciated, Craig

 

Welcome to the forum. Please go introduce yourself in the new members section when you have a chance. That 14 code is a coolant sensor. As far as being sluggish, etc. That is probably a fuel issue. Your fuel pump may be acting up. The coolant sensor is one of the more enjoyable fixes. Do that first, and surely you will be graduating into other areas of maintenance.

 

Craig:
Welcome to the forum. Below is the entry under FF14 from the Jag-Lovers XJ40 E-book. Sounds to me like it is getting at your problem.
Scott

Conditions for flagging :

After cold start, signal to ecu under 3.53 volts after 6 minutes.
Normal engine operating temp, Signal decrease of .7 volts or greater in 196 milliseconds.
Normal coolant temp sensor out of operating range, Under .1 volt, above 4.9 volts for 64 milliseconds or longer.

If FF14 is flagged, the ecu defaults to 80F.

Possible faults:

- High resistance connection between the sensor and the ecu (dirty connection at coolant temp sensor)
- Open or short circuit in wiring between coolant temp sensor and ecu.
- High resistance ground circuit in ecu circuit.
- Defective engine thermostat.
- Defective coolant temp sensor.

The coolant temp sensor has 2 wires, and is located close to the engine thermostat. They very rarely fail.

The coolant temp sensor is used to control a number of functions:

- Cranking enrichment,
- Warm up enrichment,
- Acceleration enrichment,
- Air injection,
- Idle speed control,
- Exhaust gas recirculation,
- Evap system canister purge.

To test the coolant temp sensor, measure the resistance between the two terminals hot and cold.

14F 9200 ohms
32F 5900 ohms
50F 3700 ohms
68F 2500 ohms
86F 1700 ohms
104F 1180 ohms
122F 840 ohms
140F 600 ohms
158F 435 ohms
176F 325 ohms
193F 250 ohms
212F 190 ohms