Member
Hello everyone,
I have a 2013 Jaguar XF 3.0L awd supercharged with cold air intake, stage 2 tune, upgraded crank pulley, and muffler delete. Anyways I recently blew my supercharger so had a used one from a xf that at 32k miles on it put in my car. I also had my spark plugs replaced once I got the car back I started to notice a issue. The car runs fine until you try and floor it then it starts to miss fire but no engine light and no shops computers can detect a missfire in the cylinder. It only does it under load. The original shop said o ur used supercharger is bad but I experienced a bad supercharger with my last one and this wasn’t the issue. Other stops claim that my mods are causing it which I don’t believe because it didn’t happen with my other supercharger. No one seems to know what’s wrong. I had a smoke test done to see if maybe the supercharger and intake manifold would on completely but it came back with no issues with that. I even checked all the hoses sprayed them all to see if there was a changed in rmp for a vacuum leak. That resulted in me not finding anything. I have noticed my rpms do shutter but only slightly when I had my car dynoed they noticed pulsing in the results you can see little breaks in the lines in the dyno. Some days the miss fire feel like they are not there then other days they are worse. Jaguar won’t look at it because it’s modified and no shops seems to have any solutions. Do you guys have any idea what could be wrong, please help

 

Have you checked your fuel for water? Just a thought.

 

How many kilometres/miles are on the vehicle? Are there any pending DTCs in the system?

Based on your description, it seems you may have a coil unit or injector that's about to fail or has failed. If the misfire is constant, a DTC will be set to let you know the cylinder.

 

im not getting any codes for a miss fire I’m only getting two codes U0447 p0700 which are these two none deal with the miss fire.

 

I have not checked it for water. I was told to clean my Throttle body and that may help.

 

Place your bets, mine will be on clogged catalytic converter(s). You can check it with a heat gun or a backpressure gauge, plenty of videos on youtube.

 

I was thinking cats but took it to a muffler shop and they didn’t say anything to me about it being a cat.

 

Plug wires.

 

Plug wires.

 

coil on plug...

 

What code reader are you using?
If you have miss-fires it will set a code or a pending code. Maybe your just not seeing any pending codes as posted up thread?

To check for plugged cats remove one or more O2 sensors and give the car a quick road test.
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I'm willing to bet someone sold you the wrong spark plug part no or they got dropped before you bought them and the gap is off on one or more of them. Spark plug gap is preset but things happen. If the gap is too big it will blow out up top but be fine down low.

 

Even without plug wires, there is still a rated Ohms resistance that needs to be met in order for the system to work. I suspect that one or more of the coil pack's Ohms resistance is not what it should be. Although, OP has dropped off the radar on this post, so most likely we'll never know what was wrong.

 

Vac leak

 

I was thinking ignition, too. Plugs, coils.
Good luck
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Current Hers: '13 Lexus ES350
Current Mine: '15 Jaguar XF (X250) Portfolio AWD
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