Hi All -

Just wanted to confirm my diagnosis with the smart people here before I take the car in with instructions.

The symptoms: Yesterday I took the car out to the desert. For the drive out most the way I was managing 80-90 with no problem, but partway up the hill to Palm Springs I started having trouble accelerating -- it was holding steady at 70 or 75, but if I tried to accelerate to pass it was really sluggish. Once I was over the hill on the flat again things seemed fine but I couldn't do any testing because there was a friendly CHiP officer making sure we all behaved. After sitting for 3-4 hours, the car seemed okay on the surface streets, but after running for a few miles on the highway I noticed the acceleration missing again. The car seemed pretty happy to stay at 70-75 MPH and around 2000 RPM, and it was very sluggish and unresponsive to the accelerator. It felt like a UHaul truck with a speed limiter. Back in the neighborhood it accelerated from stops fine, but never kicked in any high RPMs. No check engine light or warnings, but my TPMS is flaked out and hogs the display so I wouldn't have seen any intermittent warnings..

Today's examination: I pulled the codes and got P0101 pending and P2601 pending. I then tried to record some live data at various RPMs. I recorded at idle, 2000, and was also able to rev some short bursts up to 3500. I shut the car down for a few minutes, then reread the codes to find the P0101 pending was gone, but the P2601 pending was still there.

My diagnosis is the SC pump is failing and so the ECM shut the SC down and limited me to 2000 RPMs. This triggered the transitory P0101 because it wasn't getting enough air. Today the car was cool and the SC was able to run, so while I was trying to record the P0101 pending cleared up. So now I need to have the SC cooler pump replaced.

Does this sound like I've hit the right answer?

 

If you mean the SC intercooler coolant pump then electric pumps tend to work until they fail completely. I had the pump on my X100 fail, it threw a code & put me into limp home mode. Was a simple replacement & there are better, higher capacity pumps on the market which are cheaper than the Jaguar pump.

 

There will be codes. Furthermore, the workshop manual is available to download here and it clearly lays out the expected operation and pinpoint tests to consider when codes are thrown.
I wouldn’t guess by throwing money at parts. I’d get a proper diagnosis done first.

 

Thanks for the feedback.

John, you're right about electric motors usually failing all at once. The code says pump or circuit, so it could be an electrical glitch. Hopefully the garage will chase that gremlin down.

Guy - Yes, there are codes, and I included them in the original note. There definitely is a pump issue code, and when I consulted the repair manual before I posted, the solution for the code was to "use the specialized equipment to run the pinpoint tests." In the version of the manual I downloaded, I did not see a description of the pinpoint test, nor do I have the specialized tools, so that sort of ends that line of inquiry until I take it in. That said, the real questions I was asking (and apologies for not framing them better):
1. Would the P2601 pending code shut down down the supercharger, thus causing the loss of power?
2. Would the hypothetical shut down of the supercharger cause the transitory P0101 pending?
My actual hands-on engine mechanic knowledge came from a '67 Pontiac and a '72 Ford, so I was I was hoping that someone a bit more current with the workings of the modern computerized engine would let me know if my theory was plausible or if my supercharger is about to catastrophically self-disassemble and exit through the hood of the car.

Again, I got no check engine lights, but the car did not feel right and did not perform properly. It is now resting quietly until it can go see the Jag doctors.

 

The supercharger is belt- driven, so no, it isn't shut down.
Your ECU just dialed back the timing to prevent detonation.