Hey all, I'm having some issues with misfires in my 2016 F-Type R AWD (~56,500 miles) and am not feeling the most confident in what the shop is telling me, so I figured I would get your guys' opinions.

The last time I drove my F-Type (November 2025) I began having misfire issues immediately after a hard pull. I immediately parked it in my storage unit afterwards (it happened as we were pulling in to the lot). When I pulled the codes, I got:

• P0300 - Random misfire detected
• P0301 - Cylinder 1 misfire detected
• P0302 - Cylinder 2 misfire detected
• P0303 - Cylinder 3 misfire detected
• P1315 - Persistent misfire - catalyst damage
• Also, a historic code from 2024: P0088-85 - Fuel rail/system pressure too high (the CEL came on, but cleared on the next start-up and hasn't returned since then)

I had it towed to a shop and after their diagnosis, they claim that the high pressure fuel pumps are giving inconsistent readings and recommended:

• Replacing both high pressure fuel pumps
• If replacing the high pressure fuel pumps doesn't solve it, then replacing all 8 fuel injectors

What are your guys' opinions on this diagnosis? I feel like the shop is giving a more "guesswork and replacing parts to see if it will solve it" approach (which conveniently for them, costs a lot more money) rather than a targeted diagnosis to isolate and fix the issue(s). To my knowledge, I believe that cylinders 1-3 are all on Bank 1, so wouldn't it make more sense that the issue is isolated to some shared component(s) on that bank? Rather than completely replacing both high pressure fuel pumps? If they were the issue, I would think that I would have random misfires across cylinders on different banks rather than just on one bank, right? My current planned approach is to get clarification from them on:

• Confirmation of which cylinders and bank(s) are misfiring and whether everything points to Bank 1 only
• If they have already ruled out ignition issues on cylinders 1-3 (specifically spark plugs and ignition coils - if they have inspected the plugs and whether or not they have tried swapping coils to see if the misfire follows)
• Under what conditions do the high pressure fuel pumps show inconsistent readings (idle, under load, etc)
• If there are inconsistent readings, are they isolated to Bank 1's high pressure fuel pump, or are both pumps showing problems

Is my thought process on the right track, or do you guys have any suggestions and/or additional questions I should ask them? -- Some additional info on my car in case it helps:

• Year: 2016
• Mileage: ~56,500 miles
• VelocityAP ECU tune (stock upper and lower supercharger pulleys, not upgraded)
• VelocityAP 200 Cell Sport cats and downpipes
• Car is usually driven only 1x a week to car shows and cruises afterwards for ~6 months of the year (average, maybe 3,000 miles a year)
• I don't push the car to the max. May drive it mildly hard every once in a while, but nothing crazy at all

Any help/advice would be greatly appreciated! Thank you!

 

First thought is to eliminate low battery voltage causing random electrical glitches - fully charge the battery and start diagnosing from there. Apologies if you've already done this, but we've all been there .....

 

I would suspect timing more than a fuel pump itself with that symptom list, but further diag is needed before you throw any parts at it.

Most competent scan tools have a HPFP test function that will disable them one at a time while running and compare, to diagnose if one is failed. Good place to start.

 

There is ONE issue that is causing all these errors - throwing parts at it is irresponsible and very expensive. Replace both fuel pumps? Replace 8 injectors? What are the odds multiple parts have failed at the same time?

I agree with you and @RoverJoe - start with Bank 1, swap coils, check fuel pump function. Also checked for any frayed or loose wires / plugs.

Please keep us posted on your progress and good luck!

PS You are not alone currently:

https://www.jaguarforums.com/forum/f...1/#post2914649

 

Yep, you're on the right track. I call this the "Shotgun" diagnosis method. They do this all the time but would never do this with their money.
There is no chance that several parts failed together, in a single event. Much more likely a single component failed which impacts the fuel rail system.
Sparkplugs and Coils problems will be reported on the ECU. The algorithm that measures and reports ignition parts, works very, very well. Sparkplugs that fail in this engine, are never caused by the sparkplugs themselves. If an ignition coil fails, it's a solo act. A coil failure could cascade to trash that plug, even a cracked plug insulator could cause that coil to fail.
You have reports on every plug in one back, and 0 reports on the other bank. This indicates neither the plugs nor coils caused this problem. If you roll components between banks, you will move a set of parts just challenged to operate in a struggling mode.

Each Bank has some exclusive sensors. Whenever symptoms affect the full Bank, and 0 affect reported on the other bank, shift focus to every sensor exclusive to the affected Bank. If NTF, I'd then prove every actuator operates when I manipulate the relative sensors. I start with external actuators.

Here's a smoking gun... 1315 - Persistent misfire - catalyst damage. This one seems like it is a suck factor of 10, but it is a powerful clue. The message is a wee bit misleading.
This alert was developed due to top-down pressure on Engineers to identify conditions which they expect will harm the CAT. The misfire was measured, logged, and accumulation of misfire reports triggered this alarm. It does not measure catalyst damage, only things which they've recorded that cause damage. It precisely measures Crankshaft rotation and records events when the crankshaft angle position arrived too late or too early. The rate of errors is continuously tracked. Your engine exceeded this performance window.
We know this engine is definitely misfiring, isolated to Bank 1. We know misfires only occur immediately following high torque demand mode, or high fuel volume demand. Many actuators operate to enter and to exit this mode. Most never operate otherwise.

Now let's dismiss the impossible and improbable.
Impossible
HPFPs, these are mechanical pumps. If one of these mechanically fail, the engine cannot start. The fuel rails are continuously filled with liquid fuel; there is no storage of latent pressure. If the HPFP broke apart, injectors open but no fuel can flow. The fuel pressure is far too high to measure. You can get measured fuel pressure via the OBD comm port. This proves HPFP can supply the pressure, the sensor is reporting to the ECU, and the ECU received it.

Let's clear the dumb, easy, quick stuff. My apologies. Each bank's air supply is unique. Plz check air filter, MAFT sensor, integrity of every air supply connection, and air filter housing. In High Torque Mode, if the engine sucks in any air from the engine bay, instead of the ram air from the front of the car, the ECU adjusts everything to expect more air pressure. It has little to do with air temp, mostly the expected ram air pressure, it responds to high torque demand + vehicle speed with acceleration, so it closes blower bypass, adds injector duty cycle and advance, adjusts cams advance, changes ignition operation mode, & prolly others I forgot.

The ECU then predicts imminent Combustion conditions to control everything I listed for combustion perfection. Your engine's ECU has lost combustion supervision either while going into or out of High torque mode. It is either not able to measure something, or not able to move something within the time limit
The unpopular Tech X reported HPFPs are giving "inconsistent" readings. Hmmm, I don't think HPFPs have a way to report anything. The ECU monitors the Fuel Rail Pressure Sensors to compute fuel injector operation, and to emergency shutdown if fuel pressure is too low or 0.