Hey guys been having very intermittent which seems to be a fueling issue. 2010 Jaguars XF 5.0 supercharged. So when I first got the car, one random morning to work ! was slowly accelerating and the car was bucking like crazy so l downshifted and kept it in a higher rpm and it was fine. This issue never came back again until 2 years later. So now once every other week when I'm driving (especially on a hill) the car will start doing the same thing bucking so keep the rpm's high and it's fine. I restart the car and it doesn't have the issue. Now I have replaced the fuel injectors, spark plugs, high pressure fuel pumps, mass air flow sensors and checked for vacuum leaks. Car has a lumpy idle once it's warmed up and rpm's just slightly surge when cruising (about 50rpm or so). Now I have checked fuel pressures and everything is in spec range. I'm guessing it has to be some sort of fueling issue because I can do heavy acceleration no problem whatsoever but as soon as l'm done accelerating and I try to cruise at a normal speed it bucks a lot but then returns to normal after a few seconds and it doesn't log or throw any engine codes. Could this be a in tank fuel pump or fuel relay that's slowly going out even if the psi is good? I replaced the fuel filter and didn't seem to make a difference. If someone could point me in the right direction I would really appreciate it.

 

Have you checked that you got genuine injectors? Tons of counterfeights on market.

 

yup genuine injectors

 

What scanner are you using?
Without an operational SDD you might not be able to see deep enough into the car to diagnose it.

Lumpy idle points to a vacuum leak somewhere?
Any chance you have a leaking PCV diaphragms (Note there are 2 on the 5.0L engine)? It's pretty common but at least in my case it did set multiple codes. So no doubt about where the problem was.
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Pretty advanced scanner Autel MK900BT. And no I replaced those couple months ago. I might have to do another smoke leak down test.

 

OK good to hear they have been replaced and I think these engines are a bit lumpy at idle anyway. At least compared to an older port injection engine.
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equivalence ratio (AFR) PID is available in global obd. fuel starvation is unlikely

these MAFs have some real bizzare symptoms when they start to go. you replaced with genuine i assume?