First I'd like to say that it's good to be back on the forum after a lengthy hiatus. Second, hope everyone is doing well and have enjoyed traffic free roads in the last two months (I know I have).
For the last 18 months I have been enjoying my 2008 XKR Coupe in a very rare color combo of Frost Blue / Ivory. It's a relatively low mileage car for the year (51K) and for the most part, it was worry free until recently. Since my last service where I changed the oil and installed a pair of new K & N filters, the vehicle has developed a habit of turning on the engine light. The codes given:
P050B - Cold Start Ignition Timing Performance
P0101 - Mass or Volume Air Flow "A" Circuit Range Performance
Not sure if this would become a frequent occurrence, I simply reset the engine light and continued motoring. However, the engine light started to become frequent and it got me worrying. I checked the forum but did not find anything conclusive, except that a few members recommended to drain the ECU by disconnecting the battery and holding the positive and negative terminals together for a few minutes. After doing so and reconnecting the battery, the car transformed into a brand new vehicle. The transmission shifts became imperceptible, the shocks felt firmer, the acceleration felt smoother - the car completely transformed itself. With more frequent driving, since the pandemic started and the traffic dissipated, I have been taking the car on the road more frequently. After about 200 miles of driving, the engine light came back on - same codes as I listed above. I reset the codes again and continued driving. with every 50 miles driven, the performance of the car went back as to how it was prior to the battery disconnect. Furthermore, it has developed a somewhat rough idle, where when the car is in park or neutral the engine constantly goes up and down between 600 and 1200 RPM. In "drive", it idles perfectly. A few times, as I slowed down for a traffic light from about 60 MPH, the ignition shut down right before I stopped, as if the transmission couldn't successfully engage the 1st gear before the engine died. Back to the forum I went and read some threads where people mentioned that an old battery may be the culprit. I checked my battery and saw that it was replaced in April of 2016 - not new, but not terribly old either. So I ordered a new battery from the dealer anyway. In the meantime I continued driving the car. On Sunday, I was going about 65 MPH, when the car completely shut down on me. I was able to steer, but not accelerate. Luckily I manged to safely pull over on the shoulder and shut off the vehicle. It restarted without any drama, but the engine light was on. I checked for codes and this is what it showed:
P2105 - Throttle Actuator Control System - Forced Engine Shutdown
P2103 - Throttle Actuator "A" Control Motor Circuit High
I reset the codes just so that I could get home. This repeated 2 more times by the time I finally got home. Yesterday, I installed the new battery and the car, once again, drives like new. But today in the morning when I started it, the engine light went back on and P050B and P0101 once again showed up.
Before I take the vehicle to the a mechanic, perhaps someone can offer guidance as to what the problem can be. If I have to disconnect the battery every 200 miles or so to get that "new car feeling", I am OK with it, but if there is a truly underlying problem with the vehicle, then I don't want to take any chances. I just don't want a mechanic doing trial and error by replacing parts which are perfectly fine in order to get to the real problem. Any help with this is greatly appreciated.

 

Maybe start with those air filters. Read that the ‘R’ is sensitive to having a balanced airflow coming in. If you have them, try going back to your original filters, do the battery disconnect again, and see what happens.

 

Thanks for the suggestion. I hope that it's the filters, because that would be an inexpensive fix. However, on my 2005 XKR I had no issues with the K&N whatsoever - same engine displacement and all. Any other ideas?

 

+1 on the air filters. With a new, matched pair of OEM engine air filters you won't get a CEL. That's why they're sold in sets of 2. Some X150 owners have reported CEL issues with aftermarket engine air filters, including K&N. See: https://www.jaguarforums.com/forum/x...ilters-119498/

 

Devspider, I will be following this thread, as I have a 2008 XK 8, not R however. I do have a question about your experiences -- how do you "reset the codes?" Is that the connecting the positive and negative battery cables together that you mention for refreshing the 508 and 101 codes? Thank you!

 

Not to confuse erasing the codes and emptying the capacitors during the battery disconnect, let me explain.
1. To erase the codes I use Dash Command - a Bluetooth device which I insert into the OBD2 Port and then use the app to erase codes.
2. To reset the ECU and empty out capacitors in the electrical system, I disconnect the battery (both terminals) and then I connect the positive wire to the ground wire and leave them like that for 10 minutes. Once I connect the wires back to the battery, I have to reset the "hand" brake by pressing on the brake pedal and engaging the hand break at the same time.
If I don't do step one first, then the codes won't reset on step 2, so you have to follow in that order. Hope that helps.

 

I've had K&N filters for five years now. I've never had any hint of a problem. Ever.

 

I had the same 2 codes. P050B and P0101. Same rough idle behavior you describe, but only in cold weather. They were pointing to a vacuum leak. I also have K&N filters, but the P0101 was showing up even with the OEM filters.

The P050B went away along with the colder weather. If it was due to a vacuum leak, the colder, more dense air would make the vacuum leak more noticeable, especially during cold starts.

I haven't seen the P0101 in a while, but even after I overhauled my intake system, it showed up on the highway every now and then.

I suggest checking your PCV, intake, and vacuum systems for leaks. The rubber connector between the throttle body and T-pipe is very fragile at this age, and may break (if not already broken). Its possibble when they were changing filters, some of the intake componetns loosened up and are now drawing in un-metered air. My DIY smoke machine showed an air leak at the oil fill tube, so may want to check that as well. Check your fuel trims also.

If you can go back to your OEM filters, let us know if that fixes the issue.

If you're wondering about MAF sensors, I replaced mine with new aftermarket, then with new OEM ones. It made ZERO difference - the P0101 didn't go away.

 

Devspider I am inclined to go with gkubrak. I had a similar experience in Nov, took the dealer almost 2 months to track down the issues, there were multiple. The first was a bad MAF sensor, replaced both just because they were the same age and mileage. Next was the PCV where they detected a vacuum leak. They should use the smoke test for this to track down the leak. In my case found two leaks, replaced hoses and connectors (plastic-brittle). Also replaced the PCV valve. Although the PCV valve was bad, the codes came back, just took longer. Final diagnosis was the PCV canister, had to replace that and presto, car was healed. So I had to take the dealer to national because they kept saying the car was fixed on each issue; it was not. They would charge me each time I would bring it back for a diagnostic test. I finally had enough and they sent a tech from Mawah, NJ. Had it fixed in 4 days (part had to be ordered). Good luck, let us know what they find. I too am on LI near Roslyn.

 

Once I change out the filters, I’ll let you know the outcome. One thing I cannot stand is when a dash light alert comes on - takes away from the positive experience of owning the Jag.

 

DaveTW,
I try to buy OEM parts whenever possible, but taking the cat to the dealer makes no sense for me financially. BTW, it’s nice to know someone in my area has a similar liking for the XK. I’m in Jericho, so we’re practically neighbors.

 

Update:
last week I left my car with a mechanic to take care of the codes and rough idling. The culprit, it appears, was the throttle body - it was dirty. I only use 93 octane gas, so not sure as to why the throttle body would get so dirty. Long story short, the shop thoroughly cleaned the the part and put everything back into place. Since I picked up the car on Tuesday, I’ve been using it daily to see if the codes and rough idling would return.. So far (fingers crossed) I’m happy - the vehicle idles and drives like a dream. The engine at idle runs so smooth, like a Swiss watch, you’d think that it’s off.
At the end of the month my wife and I are planning to take a trip to Georgia, but now with rioting all over the place, the certainty of this trip remains questionable. Hopefully people will realize that violence, looting and rioting, defeats the underlying reason for protesting in the first place and things will get back to normal. Until that time, I’m happy that my Cat is ready and willing to hit the road on a short notice.
Thank you to the members who helped me with trying to identify the issue. Cheers, be well and stay safe.

 

Thanks for the reply and confirmation of a dirty TB Dev

A job that is well within the scope of even the most basic mechanic, although I've not checked mine since I bought it 18 month ago.

The fuel shouldn't be an issue at 93 American (PON) octane rating, I use 95 (RON) European fuel which, IIRC equates to American 91 (PON), a 93 at the pump American would be close to a 98 RON on this side of the pump, and we classify 99 RON as super unleaded.

No issues here as yet, I like many run K&N's and whilst they may not filter as well the flow is more consistent over more miles

Thanks again for the update