Hello Jaguar Lovers,

My XJS was shifting smoothly when I took it to the shop to renew the entire A/C system, now I have a ice cold A/C but the transmission starts in secong gear and shift nicely in third at 5800 RPM. Difficult to drive the 25MPH speed limit around town.

Any suggestion before I go back to shop to be told that I need a new transmission?

Thank you

Michel

Submitted by michel@dinomar… on Fri, 07/31/2009 - 10:07

Hello Art,

One vacuum hose was damaged above the transmission and one electrical switch was renewed, throttle was adjusted as well. $ 200 .00 later she was perfect again.

Regards Michel

Submitted by michel@dinomar… on Mon, 06/22/2009 - 20:08

Hello Dick,

I have read a lot about you, your car and your expertise, thank you for taking the time to reply. I hope the shop will use your advises and fix my problem.

Kind regards

Michel

Submitted by michel@dinomar… on Mon, 06/22/2009 - 20:01

Art,

Thanks for your help, it is nice to have Jaguar friends out there ready to help!

The car is back to the shop and I will let you know how they fix it.

Kind regards

Michel

Submitted by rcmaury@bellso… on Tue, 06/16/2009 - 16:48

From the symptons, it sounds like the vacuum modulator line was knocked loose or bypassed. It picks up on the right rear of the inlet manifold beside where the A/C vacuum system hooks up. It could have been pulled loose also. best thing to do is to trace it from the manifold to the modulator which is on the right front of the transmission and make sure it did not get moved. The rubber hose if shifted out of position can melt onto the exhaust manifold. The other option would be that the electric kickdown was disturbed or unadjusted. Make sure the wire going to the kickdown pass through on the transmission is not engerized with the throttle closed. The swiitch is on the throttle pedestal. With the throttle closed, one wire should be hot and the other not with the key on.

Submitted by silver007@shaw.ca on Tue, 06/16/2009 - 08:58

the kick down switch is near the firewall area where a c plumbing goes into the a c matrix... one of the wires could be knocked off... why would it start in second gear though. There is a single green wire for the kick down that goes to the transmission and clips onto the spade terminal ( I believe ) at the rear area of the T 4000.
If the modulator valve vacum hose was kinked or knocked off the trans would hold onto each gear and then be force shifted near redline into next gear.. why it will not start in 1st gear I have no idea . Speed in 1st gear should be around 60mph on full held down hard full throttle, and around 100 MPH in 2nd gear.....

Submitted by woebegone@mind… on Mon, 06/15/2009 - 20:27

If the kickdown works, it works.
The modulator line goes from the intake to the modulator, rubber hose at each end.

Modulator could be bad.
Hose could be off.
Steel line at manifold could be jacked over pinching off the hose.

Depends on where the high and low charge ports are for the A/C, someone not quite familiar with location of other components may have knocked off the line.
Happens.

Dave

Submitted by michel@dinomar… on Mon, 06/15/2009 - 19:14

Thanks Dave,

The sticker under the bonnet is showing a vacuum diagram for the transmission, I will check to see if all the hoses are connected, also since I have a 1988 XJS I will compare them both. I tought this was going to be easy since the car was working perfectly before I took it to the shop for the A/C work. The kickdown works well from third to second, did not try from second to first.

Regards

Michel

Submitted by woebegone@mind… on Mon, 06/15/2009 - 16:47

First step:

Do these have vacuum modulators?
Is the hose still attached to the manifold, or did it get knocked loose during the A/C work?

I don't think it's kickdown, as it would "force" first, but that could explain a 5800RPM third shift.

Is this mechanical or electronic kickdown?

Get a second opinion.

Unless the A/C shop took the car to the drags while they had it, too coincidental for this to have "just happened".