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peterpete190, Auto Technician
Category: Jaguar
Satisfied Customers: 28262
Experience:  Auto repair Technician with 17 years experience.Past ASE and other certifications.
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When driving or just starting out at low speed the shifts

Customer Question

when driving or just starting out at low speed the shifts fine but when i push the gas to go faster the car starts to shift back and forth if i slow down it will shift fine what could this be. Thank You Joe
JA: Has the vehicle turned into a gas hog? And how does it start -- same as usual?
Customer: Yes it has been using a little more gas starts fine
JA: What is the model/year of your Jaguar?
Customer: 2001 Vanden Plas
JA: Are you fixing your Vanden Plas yourself? What have you tried so far?
Customer: I changes the fuel pump my self a few months ago and has been running fine as well as the spark plugs
JA: Anything else you want the mechanic to know before I connect you?
Customer: no
Submitted: 6 months ago.
Category: Jaguar
Expert:  peterpete190 replied 6 months ago.

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

I have seen components like the transmission pressure control/regulating solenoid cause this type of fault here needing replaced as well as the throttle position sensor sending false signals causing the shifting back and forth.If the speedometer is jumping around when this occurs this can be a fault with the vehicle speed sensor but if the speedometer is not jumping around then I suspect the throttle position sensor or pressure control/regulating solenoid at fault needing replaced.

I would have the fault codes read out/checked with a compatible scan tool to see what codes are set and any codes set will help diagnose and locate this issue.The scan tool can also be used to monitor the throttle position sensor to see if it is faulty needing replaced.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete