Is there a big difference between these? I've just found out that, after my oxygen sensors have been replaced, that my car (XJR x308) has a non-SC MAF sensor installed - which is now [apparently] causing the engine to perform very poorly - gasping, surging and a feeling like it's almost missing.

My car has been checked for vacuum leaks.

The car never had any of these issues prior to the oxygen sensors being replaced - my mechanic has suggested that this is because the failed oxygen sensors wouldn't have been sending the correct information back to the ECU - so the non-SC MAF would not have been so much of an issue.

...this is when my head started to hurt...

Thoughts and comments welcome.

 

There are differences between AJ26 NA and SC as well as between AJ27 NA and SC. (4 different part numbers)

 

One of the symptoms of a faulty, or in your case, wrong, MAF is the engine hesitates
or drags while under load or idle and hesitation and jerking during acceleration. I would
check the part number to see if it corresponds to your particular engine.

 

Thanks @RandyS @motorcarman

The symptoms RandyS describes are exactly the problem I'm seeing...oddly:
Malfunctioning (if functioning at all as they were black with soot) oxygen sensors and the wrong MAF the car ran very smoothly.
Replaced the oxygen sensors and the car runs like a dog (as opposed to a cat).

Maybe the functioning oxygen sensors and wrong MAF are confusing the ECU?

 

Usually manufacturers calculates the maf flow value pretty close what engine flows at most. Doing this it gives the most measure resolution of flow vs output voltage (frequency etc)to the current engine. SC engine flows more so it has different maf characterisics. Rule of thumb is that there should be around 4V in signal wire at full flow no matter what engine is. Modern mafs outputs a frequency so this rule doesn't count anymore.
This is why using non sc maf with sc engine, engine runs poorly.

 

It is very important to have the right MAF sensor that was designed for your engine.
Rock Auto has one that I think will fit your car for around $40.
2001 JAGUAR XJR 4.0L V8 Supercharged Mass Air Flow (MAF) Sensor | RockAuto

 

When my maf broke. I did not want to mess with ultra cheap parts. Went straight to oem and it has been working since. Bought it from here:BritishParts.co.uk

 

That is great that you had that option. $228 is a nice price.

 

buy a used part slap some brakleen in there

if you can’t do that just go to the junkyard buy a bunch of mafs off old subarus and toyotas until one works.

 

Hey xalty, too late. I've purchased a new one.

I've received lots of comments that there is a significant difference between the MAFs, now that I have the new on installed my cat is running beautifully!

...however, the mechanic did say that the MAP sensor is missing completely (looks like someone zip-tied the cable/hose where it should be out of sight and just plugged the end of the hose.

 

Yes sir, these ladies are equipped with both a MAP sensor and a MAF sensor, which gives the engine a much more
accurate reading of air density that is not affected by changes in ambient temperature. Some forum members are
inclined to replace from the Jaguar catalog, however there are much less expensive parts that do the job. As for my
personal observation, parts from the Jaguar house normally run three times higher than aftermarket parts.

 

Map do exist in these cars. But not in ROW wehicles until 2001 etc. My 2000 year model does not have anything else than map sensor bracket screw hole. My guess is that map sensor is pretty much used for egr only in these cars?

 

The Jaguar MAP sensor which was part No. C2C22616 fitted the following:
Xk8 Coupe/convertible 1997 - 2006
Classic, S-type 1999 - 2008 Classic,
Xj 2003 - 2009 (from G00442 To H32732)
Classic, X-type 2001 - 2010 Classic,
Xk 2006 - 2014 (from B00379),
Xf 2009 - 2015,
Xj 2010 > (from V00001). Authentic Jaguar Part.