Jaguar XJ Diesel: Rough Run + Poor Power After Repairs

Having experienced similar symptoms with my 2006 Jaguar S Type 2.7 Diesel, I can confirm this points to injection system problems. The rough running, jerking, and power loss are classic signs of faulty fuel injectors, which directly impact the air-fuel ratio. My car showed identical symptoms, hesitation during acceleration and constant check engine warnings. The diagnosis revealed two defective injectors that were causing irregular fuel spray patterns. This created uneven combustion and poor engine performance. The repair involved replacing multiple injectors and cleaning the intake manifold, as carbon deposits had built up due to the improper fuel atomization. This was definitely a serious issue that required immediate attention, as continuing to drive with faulty injectors risks damaging the catalytic converter and other engine components. Key indicators it was injector-related: Rough idle, Unusual misfiring, Significant power loss, Inconsistent acceleration, Increased fuel consumption This type of issue requires specialized diagnostic equipment and expertise with diesel injection systems. The repair is complex since injectors must be coded to the engine management system after replacement.

Thanks for sharing those details about the S Type injector problems. My XJ had nearly identical symptoms. The rough running and check engine light were really concerning. The intake manifold cleaning and injector replacement fixed most issues, but I noticed the EGR valve needed attention too. Did you remember roughly what the total repair cost was? Just wondering if it was similar to mine. Also curious if youve had any other problems crop up since getting the injectors sorted? The spark plugs on mine started acting up a few months later but that might have been unrelated.

Good news, I got the injection system fully repaired and my S Type is running perfectly now. The repair came to 515€ for replacing the defective injector, which resolved the lean fuel mixture issue completely. The oxygen sensor readings confirm the air-fuel ratio is now optimal. Since fixing the bad injector, the engine performance has been flawless, no more jerking during acceleration or check engine light warnings. I did regular maintenance but had no other major issues pop up. The catalytic converter and other components were fortunately undamaged from the lean running condition. Your spark plug problems sound unrelated, as they typically wear independently of injection system issues. However, its worth monitoring the throttle body and fuel delivery system for any early warning signs of future problems. Regular diagnostic checks can catch issues before they become serious. I can understand your concern after the previous bad experience, but getting the injection system properly repaired was definitely worth the investment for restored performance and reliability.

I took my XJ to a reputable diesel specialist after reading the suggestions here. The diagnosis confirmed faulty injectors were causing the lean condition. The mechanic found carbon buildup in the intake manifold and a partially clogged EGR valve contributing to the rough running. The total repair came to 1200€ including: 2 new injectors with coding, Intake manifold cleaning, EGR valve replacement, Full diagnostic testing After the repairs, the engine runs smooth with proper throttle response and no check engine light. The air-fuel ratio is now correct according to the scan tool readings. Fuel economy has improved significantly too. The specialist explained that delaying injector replacement likely caused the extra carbon deposits. While expensive, getting it properly fixed by someone who knew diesel systems was worth it. No more jerking or power loss issues since the repair.