Cadillac XT5's Fuel Injection Issues Cause Multiple Symptoms

Had similar issues with a Cadillac XT4 (2020) last year. The symptoms matched exactly, high fuel consumption, rough idle, and smoke under power. The fuel injection system was indeed the culprit, specifically faulty injector connections and a degraded wiring harness. The maintenance process revealed multiple issues: corroded electrical connectors at the injectors and compromised insulation on several power delivery wires. The system was misfiring, causing unburned fuel to exit through the exhaust, explaining the smoke and poor petrol economy. This qualified as a serious issue since compromised injection system performance can lead to catalytic converter damage if left unchecked. The repair involved: Testing individual injector resistance, Replacing the main wiring harness, Cleaning injector connections, Full system diagnostic reset A proper repair shop will need specialized diagnostic equipment to properly test the fuel injection system. The job requires removing several engine components to access the harness, so selecting a shop with manufacturer-specific experience is important. The symptoms indicate this needs immediate attention to prevent additional engine system damage.

Thanks for the detailed information about your XT4 issues. The symptoms sound identical to what I have been experiencing. Your explanation about the petrol injection system makes a lot of sense, especially regarding the smoke and engine performance problems. Before I take my car in for maintenance, do you remember roughly how much you paid for the complete repair? Also curious if you have had any recurring issues with the injection system or if the fix solved everything completely? The air quality around my engine bay has been quite poor lately so I want to make sure I address any potential fuel leak issues while its in the shop.

Just wanted to follow up on the repair costs since you asked. The engine performance issues were completely resolved after fixing the injection system. It turned out to be a simpler fix than initially expected, the mechanic found a faulty cable connection that was causing the system to misfire. The total bill came to 95€ for the repair work. Since the fix, the engine has been running smoothly with no smoke or stalling problems. The fuel consumption returned to normal levels and there have been zero recurring issues with the injection system. The air quality concerns you mentioned should definitely improve once the injection system is properly functioning, as unburned fuel won't be escaping into the engine bay. If your symptoms are similar to what my XT4 experienced, chances are good you might have a similarly straightforward fix. Getting it checked promptly will help prevent any potential damage to other engine components.

I finally took my Cadillac to a certified mechanic last week based on the helpful advice here. The engine diagnosis confirmed what was suspected, a faulty injection system causing the poor performance and smoke issues. The maintenance team found corroded wiring connections affecting the fuel delivery, similar to what was described. The repair included cleaning the injection system and replacing some damaged power cables. The air quality in the engine bay has significantly improved since the fix. Total cost came to 120€, which was reasonable considering the work done. The engine now runs perfectly, no more stalling, excessive fuel consumption is back to normal, and zero smoke under acceleration. Really glad I got this sorted before it could cause more serious issues. Will definitely keep a closer eye on regular maintenance schedules going forward to catch any potential problems early. Thanks for helping point me in the right direction with the diagnosis.