Having problems with your Jaguar XJ6 ?
My xj6 runs at high rpms and accelerates on its own
\015 I just bought a 1997 xj6 with 65k in mileage. it runs at high rpms and accelerates on its own. about 14-1600 rpm in park and the acceleration whenyou start to push the gas makes it impossible to drive. the rpms were at about 2000 before I changed the spark plugs. check engine light says that it has a cylinder one misfire. It has been suggested to me by a few mechanics that it could be a bad throttle positioning sensor, idle air control valve (even though it doesn't have one) and clogged catylitic converters.Help!!\015
None of those possible problems have anything to do with idle speed. The first thing might be a very weak throttle return spring. The next would be a sticky throttle cable or foot feed pedal that isn't moving freely. Another possibility is a vacuum leak somewhere. Did changing the spark plug in #1 cylinder help the misfire? If not, you may have a partially plugged injector. Fixing the misfire will only increase idle speed some more. Look for an idle speed motor near the throttle body that is supposed to raise idle speed when the engine is cold and lower it back when the engine warms up. Check to see if it is holding the speed too high. If the throttle position sensor tells the computer where the idle speed motor is set, then it could have an effect on idle speed if the sensor is bad. The position sensor is just a fancy potentiometer. Hope some of this helps.
It sounds very much like a map sensor. For the high idle and acceleration. But the clogs? Replace them. In the cylinder one did you also replace the spark plug wire? If you did then there is an ignition timing fault.
Repair Help & Product Troubleshooting for Jaguar XJ6
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