I have an 09 Supercharged XF that's having some idle issues with no dash lights on (New plugs, coil, and fuel filter) and I'm told to try cleaning the throttle body since I never have, but I'm getting mixed answers as to where the throttle body is located in the 4.2L SC engine. Anyone know where its located exactly?

 

Can you be more specific about "no dash lights on"? Do you mean the instrument panel doesn't show anything when you turn on the ignition, or the gauges don't light up, or something? If so, I have no idea why cleaning the throttle body would be a solution to this. As with most things electrical on this car, I'd be looking at getting a code reader on there as it can tell you a lot about what's going on and wiring/fuses to check.

 

I think he is trying to say that the car idles very rough but there are no "error" lights on - check engine or anything else.

 

Ah good spot, apologies.

In my experience most idle issues are caused by vacuum leaks rather than throttle bodies, and it's worth pointing out that Jaguar specifically advise against cleaning the throttle body on the 5.0 as the small amount of carbon that builds up on the plate is actually seen as beneficial in sealing against leaks - not sure if this also applies to the 4.2.

I'd still get a code reader on there to see if any codes have been logged, especially with regards to banks running lean etc - these aren't always enough to put the MIL light on, and could point to a vacuum leak of some sort. Also a visual inspection of vacuum hoses is a good start.
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Sorry I wasn't clear but yes I meant there are no warning/error lights or CEL on, also there are no stored codes when I checked a couple of days ago. My first assumption was in fact a vacuum leak which I also did not find.

 

How did you look? You want an OBD tool with live data - see the many threads about checking fuel trims.

Avoid "cleaning" the TB as it has a special coating that's easily damaged and replacement is costly and painful. Last resort. Very last.

 

If you mean how did I look for the codes, I have an OBD reader attached to the car that will show me codes, if any, usually when the car's CEL is on. I did a visual inspection followed by the 'Water spray trick' for the vacuum leak.
Okay I'll hold off on cleaning the throttle body to prevent damage, thanks for the tip.

 

Not much of a way to go after vac leaks on any modern car.

 

Well it looks like I've got some codes, P0174, P0171, P07E8, and P050B, most recent ones are the first 3. Think I'll start with MAF sensors and checking for a leak again.