Hello,
I have some doubt about my supercharger, during kickdown I have awful acceleration but in "normal" cruising the power feeling seems not to be one from a 400 HP engine.
I would like to measure the pressure in the inlet manifold but I do not find the sensor to read with my OBD reader? Should I look at the MAF sensor?
I have some oil seepages on the top of the supercharger and may be something is going wrong with the seals...

Regards,

Daniel

XKR 2002 4.2L

 

Your year doesn't have a boost sensor, so you can only measure that with a seperate pressure meter unfortunately. Would be a good test though, as a slight leak would not only let air out lowering power, the mixture would also get richer lowring the output again.

But this woudln't cause a difference in power output, as the sports mode only changes the shift behaviour, not engine output.

 

What years do have a boost sensor?

 

Sorry not for our model years at least. Not sure when it got introduced, at least from the 5.0 ltr versions, but I think I have seen it before on late 4.2 models

 

Well according to the manuals for the 4.2 XK100 cars these are fitted with a MAP sensor, as well as a MAF sensor

Does this not measure the boost pressure? I take it this stands for Manifold Absolute Pressure?

Though I don't know if this info is available to a standard OBD reader. Probably need an Autoenginuity!

 

Thank you very much for your replies. After reading your answers,it's logical to have a look to the MAP sensor. My OBD reader is "compatible AE" so I hope I will be able to read the MAP value when cruising and kick down.
The actuator seems activated by a simple vacuum signal, isn't it??
I find no description of this system for the 4.2 engine then not easy to understand how does it works!!

Regards,

Daniel

 

The map sensor sits before the supercharger, so only measures the vacuum. This one is available for obdii readers.

 

Avos, you mean there is no MAP sensor on an 4.2 SC engine?

In this case I have to find a place to connect a pressure meter but there is not a lot of space around!

Do you know what pressure is expected after the boost ? (for the pressure meter range)

Daniel

 

The only information I can find, since my previous post is:

The MAP sensor is post throttle but pre-supercharger. Therefore the maximum reading is only every going to be close to atmospheric. However when the throttle is closed the sensor will read less than atmospheric.

The engine only has a MAP sensor to diagnose problems with the EGR valve. All the fuelling calcs are done using the MAF readings.