This is happening on the hot days. I have to take off very gently, otherwise the engine backfires into intake. When moving everything is Ok, but I lost that pleasure of acceleration from standstill. I don't have any fault codes stored in the system even after several backfiring take-offs. Any idea where to look?

 

I hate to say it, but I would look at those spark plugs you recently installed. Brisk is a racing plug and may not be suitable for the Jaguar. Jaguars are very sensitive to change.

 

Past that and common issue is the mass air flow sensor being lazy. It doesnt keep up with the demands of the engine when you open the throttle. So you dont get enough fuel=lean=backfire it the intake
rich=fuel going out in the exhaust=backfiring exhaust

 

Brisk plugs were recommended to me by a person who uses them in Jaguars and Aston Martins - street and racing as well - for years. I did not have this backfiring problem last summer. Is the MAF deteriorating performance something common? Once I tried to clean a throttle body and result was the fail safe mode. and just about everything failing messages. I had to perform a few hard resets to get engine work again properly, thus I am just a little reluctant to mess with the MAF.

 

Yes its common thats why i said it