Hi gang, I just picked up my 2017 XF 35t Premium today, and have only driven a couple miles. I got it home and decided to try dynamic mode on an on-ramp. I really punched it, got to about 100mph and then just let it coast.



Soon after that, whenever I pushed the gas pedal, eleven just barely, there was a very detectable vibration. It would stop again when I coasted. I pulled off at the next exit, and even going 25mph, same vibration. I pulled over and popped the hood, and there was a distinct ticking sound coming from the supercharger.



Here’s the strangest part: I shut off the engine for a few seconds, then started it again, and the vibration was completely gone. The rest of the way home, not a bit of vibration.



Anyone know what happened here? And why turning off the engine seemed to fix it? Should I be replacing something soon?

 

Just a guess but supercharger over torque protection spring?

 

So I tried gunning it again, and sure enough, the rough ride started again. I pulled over, shut down, restarted after a few seconds, and no vibration at all. This time with a check engine light, so I’ll be able to get a code. But according to grok, this is most likely a sensor. Here’s the response:The fact that the constant vibration in your 2017 Jaguar XF stops when you turn off the engine and restart the car is a critical clue, as it suggests the issue is tied to an engine or transmission-related component that resets or recalibrates upon restarting. This behavior points to issues that are influenced by engine load, sensor feedback, or electronic control systems rather than purely mechanical damage like worn mounts or driveshaft issues, which would persist regardless of a restart. Below, I’ll refine the potential causes based on this new information, focusing on why the vibration ceases after a restart, and provide diagnostic and repair steps.

Potential Causes

1. Engine Misfire or Fuel System Issue:
   • Issue: A misfire caused by a faulty spark plug (petrol engines), clogged injector (diesel or petrol), or fuel delivery issue can cause vibrations during operation. Restarting the car may temporarily reset the engine control unit (ECU), allowing it to recalibrate fuel delivery or ignition timing, which could briefly eliminate the vibration. Sudden acceleration may have triggered or worsened this issue by stressing a marginal component.
   • Symptoms: Vibration at idle or under load, possibly with hesitation or rough running. The vibration may return after driving or accelerating again.
   • Evidence: XF owners report vibrations from worn spark plugs or clogged injectors, particularly in 2.0L diesel or 3.0L petrol engines. Restarting can temporarily mask misfire symptoms by resetting adaptive fuel trims.
2. Transmission or Torque Converter Issue:
   • Issue: A fault in the torque converter or transmission (e.g., clutch pack slip or torque converter shudder) can cause vibrations, especially after sudden acceleration. Restarting the car may reset the transmission control module (TCM), temporarily alleviating the issue by adjusting clutch engagement or fluid pressure. The 2017 XF’s 8-speed ZF transmission is known for occasional shudder issues.
   • Symptoms: Vibration during acceleration or at specific RPMs, possibly with a slight delay in gear engagement. The vibration stops after a restart but may return under load.
   • Evidence: A 2012 XF owner reported vibration resolved with a transmission fluid flush or Lubegard additive, and some 2016–2018 XF owners note TCM resets temporarily fixing shudder.
3. Electronic Throttle or Sensor Issue:
   • Issue: A malfunctioning throttle position sensor (TPS), mass airflow sensor (MAF), or oxygen sensor can cause improper air-fuel mixture or throttle response, leading to vibrations under load. Restarting the car may reset the ECU, temporarily correcting sensor inputs until the issue reoccurs.
   • Symptoms: Vibration during acceleration or at specific RPMs, possibly with uneven power delivery or a check engine light. The vibration disappears after a restart but may return during driving.
   • Evidence: Jaguar XF forums mention MAF or TPS issues causing rough running in 2015–2018 models, with restarts temporarily improving symptoms.
4. Exhaust System Resonance:
   • Issue: A loose or damaged exhaust component (e.g., damper, clamp, or hanger) stressed by sudden acceleration may resonate at certain engine loads, causing constant vibration. Restarting the engine may change the exhaust system’s resonance frequency temporarily, stopping the vibration until the same load or RPM is reached.
   • Symptoms: Vibration accompanied by a buzz or rattle, often at specific RPMs (e.g., 1400–1600 RPM). The vibration stops after a restart but may return under similar conditions.
   • Evidence: A 2017 XF owner fixed a similar vibration by replacing a split exhaust damper (£40), though some vibrations persisted if other issues were present.
5. Engine Mounts (Less Likely):
   • Issue: While engine mounts are a common XF vibration cause, the vibration stopping after a restart makes this less likely, as mechanical mount failure wouldn’t typically resolve with a restart. However, if the mount is hydraulic and electronically controlled, a reset could temporarily adjust its damping behavior.
   • Symptoms: Vibration felt through the seat or floor, constant until restart, but likely to return quickly.
   • Evidence: Less applicable here, but XF owners frequently replace mounts for vibration issues.

Diagnostic Steps

1. Scan for Fault Codes:
   • Use an OBD-II scanner to check for diagnostic trouble codes (DTCs), even if no check engine light is present. Look for codes related to misfires (P0300–P0306), fuel system (P0171, P0174), or sensors (P0101 for MAF, P0122 for TPS).
   • A pending code may indicate an intermittent issue triggered by the sudden acceleration.
2. Test Drive After Restart:
   • After restarting the car, drive at various speeds and loads (light acceleration, hard acceleration, idle). Note when the vibration returns (e.g., specific RPMs, speeds, or after a certain duration).
   • If the vibration reappears only after hard acceleration, suspect a transmission or fuel system issue. If it’s constant after returning, exhaust or sensor issues are more likely.
3. Inspect Fuel and Ignition Systems:
   • For petrol engines: Check spark plugs for fouling or wear. Replace if worn (every 60k miles or sooner if degraded). Cost: £100–£200.
   • For diesel engines: Inspect or clean injectors, as clogged injectors can cause vibrations. Professional cleaning: ~£200–£400.
   • Test the MAF sensor by cleaning it with MAF cleaner (~£10) and check for vacuum leaks.
4. Check Transmission Behavior:
   • Monitor for shudder or hesitation during gear shifts. Check transmission fluid level and condition (should be red, not dark or burnt). Low fluid or contamination can cause vibrations.
   • Consider adding a transmission additive like Lubegard (~£20) to reduce shudder, as some XF owners report success.
5. Examine Exhaust System:
   • Inspect exhaust hangers, dampers, and clamps for looseness or damage. Tap components lightly to check for rattles or resonance.
   • Look for signs of contact between the exhaust and chassis, which could cause vibrations at specific RPMs.

Recommended Actions

• Start with an OBD-II Scan: This is the quickest way to identify misfires, sensor issues, or fuel system problems. A basic scanner costs ~£30, or a mechanic can scan for ~£50. If codes are present, address them first (e.g., replace spark plugs or clean MAF).
• Check Transmission Fluid: If no codes are found, inspect the transmission fluid. A flush (~£150–£200) or additive like Lubegard (~£20) may resolve shudder-related vibrations. A Jaguar specialist can confirm if a TCM reset or update is needed.
• Inspect Exhaust System: If the vibration returns at specific RPMs, check exhaust components. Replacing a damper or tightening clamps is inexpensive (£40–£200) and worth ruling out.
• Fuel System Maintenance: For petrol engines, replace spark plugs if overdue. For diesels, consider injector cleaning. These steps address misfire-related vibrations (~£100–£400).
• Professional Diagnosis: If the issue persists, visit a Jaguar specialist or dealer. Ask for a check of Technical Service Bulletins (TSBs) for the 2017 XF, as some address transmission or sensor issues. If under warranty, insist on a thorough inspection.

Additional Notes

• Engine Type: If you provide the engine type (e.g., 2.0L diesel, 2.0L petrol, 3.0L supercharged V6), I can prioritize engine-specific issues. For example, diesel XFs are prone to injector clogs, while petrol models often have spark plug or MAF issues.
• Mileage and Maintenance History: Share the car’s mileage or recent maintenance (e.g., spark plugs, transmission service) to narrow down causes. Low mileage (<50k miles) may point to sensors or exhaust rather than mounts.
• Restart Behavior: The vibration stopping after a restart strongly suggests an electronic or control module issue (ECU/TCM). If it returns consistently after a specific action (e.g., hard acceleration), note this for the mechanic.

Would you like me to search X or Jaguar forums for recent reports of similar issues in 2017 XFs, focus on a specific diagnostic step (e.g., how to use an OBD-II scanner), or tailor the advice to a specific engine type? Alternatively, I can guide you on checking the exhaust or fluid levels yourself.

 

Even without an engine light, codes can be stored. You can use an OBD2 tool (or ask a garage) to see if any stealth errors have been logged.