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Matt, Engineer
Category: Jaguar
Satisfied Customers: 21876
Experience:  Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
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The model is S type and it is 2000 model, I had a mechanic

Customer Question

Hi Richard:
JA: What is the model/year of your Jaguar?
Customer: The model is S type and it is 2000 model
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: I had a mechanic but not making much progress. I have changed the spark plugs and coils but the rev remains the same, not exceeding 2800 rpm upon starting and it will increase abut on the road but soon after receds to 2500 rpm and below
JA: How many miles are on the car? When did you last change the plugs?
Customer: Mileage is 92000 and the plugs were changed in Feb. last. The coils were changed last month.
JA: Anything else you want the mechanic to know before I connect you?
Customer: I used to get on the dash " Fail gate mode" but I had ignored it. It came on infrequently but hasn't done so for a while.
Submitted: 10 months ago.
Category: Jaguar
Expert:  Matt replied 10 months ago.


I'd say the next step is have the car plugged into a diagnostic tool , one that can monitor sensor readings live so you can see if it all makes sense

from your description I'd say it could be a lack of fuel pressure or an electrical actuator or sensor at fault .Usually when you can cycle the ignition key on / off and then restart the engine and the fault is gone temporarily this indicates that this is an electrical component causing this issue.

This could be a wiring issue as things tend to expand when hot and its possible a poor or partial electrical connection is being pushed apart on one of the major sensors so check the connection plug and wiring to the following;

Airflow meter

Crank position sensor

Cam position sensor

O2 sensor

Throttle position sensor

unplug each in turn and use some switch / contact cleaner spray on the pins to ensure its all grease / dirt free

Also worth checking the connections to the fuel pump for the same reason - unplug each in turn and give them a good squirt of switch / contact cleaner - Not WD40

and also unplug and inspect the main power relays and fuses for signs of overheating or corroded terminals - so the ones for the ECU and the fuel pump

And also unplug the wiring loom connections in the engine bay one at time and inspect for corroded or recessed pins.

Expert:  Matt replied 10 months ago.


do you still need help?

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