Need help. Well maintained XF Supercharged has a compression problem and local Jag mechanics are stumped.
"Restricted Performance" alert came on.. Hot day 95 degrees... driving in stop and go traffic. Limited compression.... step on gas, no response.... no downshifting, just maintain current speed. Limped into dealership. Had it for three days,,, said it was the mass air flow sensor. Replaced... $500... All well next day until hot afternoon, 94 degrees... same issue "Restricted Performance" light came on. .Limped back.
Had it for five days... "cannot duplicate"... kept "to drive in hot weather"... still no resolution.
Diagnostics verifies "Restricted Performance" illuminating.
Still in shop and they are stumped.
Anyone?
Thanks, Joe Glasson

 

You're in the F-type forum. Guessing you have a 4.2l V8 - different engine in the F-type (5.0l).

 

sounds like insufficient intercooler cooling which can lead to engine knock under boost and damage hence the RP. Should look at the pump which may be failing and or airflow blockage in the SC radiator. Have seen mice and squirrels build nest and debris around the radiator or just crud. This is just thinking out loud and what I would look into myself. The pump is a bosch pump and readily avail as an upgrade unit also. Worth a charge for improvement in sc cooling anyway. Otherwise there "should be" codes for restricted performance as well as freeze frame data to see what the car saw for restricted performance. Another thing to look at would eb the engine fan. If not fully running at required speed and airflow it can cause a running hotter than normal in traffic as you describe. Ie the fan runs but is failing and running slower than it should. Although this usually causes a ac complaint rather than restricted performance