All, the kitty is getting a hiccup (random P0101 codes). I have an ELM 327 unit and am using it through my android phone (Torque app). This is a great tool to have to figure stuff out. But, I am finding that it is "limited". What I mean by this is looking in the service manual, it references the P0101 code, but then it breaks it down even further into P0101-XX (where XX is 2 more numbers that go into detail about whether it shorted to ground, shorted to power, open circuit, etc). Is there a code reader out there that will tell me these extended numbers (the XX part)?

Back to the issue I am attempting to resolve. What I am experiencing is watching the MAF sensor and the air flow that it is seeing, getting on the gas results in no errors and regardless of how fast or easy I get into the throttle, the computer is happy. If I get off the gas easy, the car seems happy about that. At idle the car is happy. ONly when I let my foot off of the gas does it see an error (red circle on the graph using the Torque App). If I get off the gas slowly, then it is happy. But, if I am say cruising down the highway and let off the gas to start coasting, the computer sees the initial drop as a problem. Anyone have any ideas of why the computer would be having an issue with this? Looking in the maintenance manual for potential problems, it references a failed MAF (not my case since it reads all of the time) and leaks in the intake piping (haven't looked, but would think this would be also associated with P0171 and/or P0174 codes). IF the MAF was dirty, I would think I would be getting low air flows, not to mention that I cleaned the sensor back in March. Granted, it wouldn't hurt to clean it yet again just to see if things improve.

Assuming that a MAF is bad, buying a new one is nothing short of outrageous. Some of them go as high as $500 for the sensor on e-bay. Granted, I have been able to find some down as low as $80. Jaguar wants $224 for the sensor. Even then, it will be a trial and error game of installing a new sensor, hoping that I got the correct side the first time.

Here are some air flow numbers that I am getting from my Torque app. Could someone else confirm what I am getting?

Idle (cold engine): 10 g/sec
Idle (hot engine): 7 g/sec
Cruising at 70 mph, level ground (2,000 RPM): 40 g/sec.

 

Thermo do you have the OEM style paper air filters or KN style. A, maybe, just a WAG the air flow is not matched cfm at idling down.

 

XJsss, I do have the oil-cotton K&N filters installed in the car. But, I can't imagine those filters being a problem as I have had them in for 2 years now. I will admit that once in a blue moon I would get the P0101 codes, but I would clear it and it would go away for a few months. But, I have gotten 3 codes in the last week. I cannot attribute it to over oiling the filters as 1) I purposely under oil them to prevent having issues, and 2) the last time I cleaned them was 4 months ago and if I would have issues, it would have occurred a long, long time ago.

YOu do bring up a good point about the air flows not being matched while unloading the engine. But, what can you really do about that. Unless I managed to poke a hole in one of the filters, the air flows should balance themselves out due to having to go through the filter media.

This one has me guessing. Kinda like I wish I could see the individual air flows from each side of the intake so I could get a better idea of what is going on. Granted, it may take me pulling out my multimeter and seeing if I can spot a difference in voltages between the sides. But, at idle, it is going to be difficult to see any difference and revving the engine and letting the air flow come down is going to be fun trying to watch 2 different multimeters at the same time and figuring out the difference on the fly.

 

You may need IDS or the like.

The extra code info is via what is known as failure type byte (FTB). It post-dates most OBD tools and especially their software.

 

No experience of the Jag, but on previous cars I've owned and run forums for, oiled filters can slowly destroy the MAF sensors.

If you have access to live data, are the trims shifting on either bank?

 

I know you have been running them for 2 years but Brutal has posted about using factory matched air filters before.
Just a guess?
.
.
.

 

Just an update to those that may experience this issue. The problem was not the filters. It turned out the code was because of varnish (burnt oil) build up on the throttle body. After cleaning the throttle body, it has been good with the problem never returning. Still running the K&N filters with no issues.