USA 1977 Jaguar XJS has a MPS (Lucas 2PS 73164A)

Hello everyone,
My USA 1977 Jaguar XJS has a MPS (Lucas 2PS 73164A) with a Yellow and a Brown stick dot affixed.
I've performed the vacuum leak and resistance checks called for...all were OK.
My question is this; if I apply a small vacuum on the sensor to check the actual functionality, should the resistance change? If so, what would be an acceptable range?

Thank you, and I'm looking forward to your reply.
Harry

Hi Harry,

thank you for repeating this question in forum. What you can diagnose on your MAP sensor

• Outside still original rivets, black cop hopefully still in place. If the black cap is also still in good shape, it is a good estimate to believe that adjustment screw was hopefully never touched
• Resistance of primary and secondary coil in tolerance and no contact to housing. Resistance is indepent of vacuum applied
• Pull a vacuum of -0.5 Bar (-7.3 psi) and wathc how wuickly it falls to -0.45 Bar (-6.5 psi). If that takes much longer than 10 seconds, then it is fine

More you cannot do. What I do additionally:

• Adjust ambient pressure via a apecial cover to a defined value, very important on this type 3 MAP sensor
• Then apply inside differential vacuum in comparison to adjusted environmental pressure
• Finally I reduce enviornental pressure to measure altitude compensation
• I excite primary coils with a freuency close to ECU and then measure how variable transformer in MAP sensor reacts

It is a pity you are so far away. Otherwise we could have a win - win situation: I would measure your MAP sensor for free and if it works correctly would have another reference for my list. But the US is a problem.