Hi i am a new member and i have a 88 3.6 jaguar xj6 sovereign and when i start it from cold it drops to 500rpm sometimes 300rpm and shudders for about 10/15secs then sits at 1000rpm is this normal? And if not what would be causing this? Thanks i am in new zealand but car was imported from england

 

Sounds like you could do with an intake service, i.e. remove all the intake plumbing and clean out the muck and carbon. Also there is an idle air control valve (IACV) that gets carboned up and could benefit from a cleanup. The throttle body butterfly also gets carbon deposits on the back side and this will affect the idle too.

Basically, clean all the intake and then re-set the idle. The procedure for doing so are in the archive. Search intake, IACV, throtttle body, idle setting etc.

Larry

 

Hi Jdmjag1,

Welcome to the Jaguar Forums! It's great to have you with us!

In addition to Larry's excellent advice, you may be able to find a clue by checking the Vehicle Condition Monitor for any stored Diagnostic Trouble Codes (DTCs). To do so, turn the key to position II (Ignition ON) but do not start the engine. Press and release the VCM button on the trip computer beside the steering wheel. Now watch for a message in the small display window below the speedometer where the mileage display/odometer normally appears. DTCs are displayed in the format of "FF" or "Fuel Fault" and a numeral. If a DTC appears, write it down exactly as it appears and post it here and we'll try to help.

In the meantime, here are some references to help you on your Jaguar journey:

XJ40 'HOW TO' quick links thread

Haynes XJ40 Manual (U.K. edition missing a couple of chapters but free)

XJ40 Electrical Guide 1988

Power Hydraulic System Manual (Brakes, Self-Leveling Suspension)

Exploded parts diagrams and part numbers: jaguarclassicparts.com

Parts: see our forum sponsors, some of whom offer discounts to Jaguar Forums members.

Cheers,

Don