Queen and Country.
I had my fluid level checked 3 days ago. It was full and clear. I saw the fluid as the fill plug was removed.
I am now debating to have a full transmission service and fluid change since that is the only thing left. On the other hand, I have not felt the 1st gear lag this week. Up to now, I could expect it to occur at least weekly. As mentioned in earlier post, recently I have done a battery hard reset, attached a CTEK battery monitor, and engine oil and filter change. Hard reset might have helped.
I want to drive the car at least another week or so before committing to a fluid change.

George05.
I do see John's (To the Garage) YouTube series. Both Purdy and red XK8. I just have not worked up enough courage to try the kickdown reset yet. I have read where some BMW owners with
ZF trannys tried that and then could not start their cars. So for the moment, I am going to hold off.

____________________
2010 XK Coupe 5.0L NA

 

In that case you are somewhat confirming that its just a transmission learning issue.

Just one question. The plug was removed with the engine running?
I am assuming you are aware it holds more than the plug level. In fact one of the test to see if the pump is failing is that there will be no difference between pulling out plug with engine off vs running.

 

No problem . it works on mine , I do it twice a year have done last 3-4 years

 

That is definitely what happens when you engage manual mode by touching a paddle. As you were in D when you engaged manual, the car will upshift itself when you hit the redline (if you started in S, it wouldn't; it just sits on the limiter). If you don't touch the paddles again and drive at a relatively constant speed, it will revert to automatic shifting after a short time. You can force that by pulling & holding the "+" paddle until the display changes back to PRNDS.

So, you may be accidentally clipping the paddle, e.g. when you are using the indicator stalk, throwing the car into manual and thus causing delayed changes. Then, because you don't use the paddles, the car goes back to automatic mode and it's all normal again. I've done this occasionally myself, and it's "WTF" for a second or two until I realise what I've done.

 

To Ngarara and Shemp,
In my post on Aug. 26th, I admitted that I must have have accidentally hit one of the paddles; probably the left (-) one since I pretty much only hold the steering wheel with my left hand. And therefore the car was operating normally on that occasion. Queen and Country also brought that to my attention as well. Thank you all for your input.
But for the 1st or 2nd gear lagging issue that I reported in my original post on this thread, for the time being it is still being pursued. I am driving the car more in the hope that if it occurs again, maybe a fault code will appear to offer some diagnostic guidance. If it does not happen again in let's say the next 3 weeks, I will request closing this thread. Incidentally it has been over 2 weeks since the last time that I felt the lag. I was getting the condition at least weekly.

____________________
2010 XK Coupe 5.0L NA

 

Well I am ready to eat some crow and suffer the embarrassment. I think that I caused my own lag "problem" originally reported. Again, I must have accidentally hit one of the paddle shifters. I say must have because I certainly did not do it intentionally or feel the touch pressure at the time. Yesterday I did some controlled driving on quiet streets and used the paddles in manual mode; never turning the gear shifter out of D(rive) to S(port). And I got the same driving experience that I first mentioned. What I should have done was just press the + shifter when I felt the gear lag and I would upshifted as normal. Actually I should have tested the paddles in a test drive before purchasing the car so that I would at least have had some experience with paddles and shifting. I was just overly focused in thinking that I had detected a unique issue in Drive mode with transmission shifting. But in fact the car was behaving as it should.

PK4144 - On August 23rd, you first suggested that I try Sport mode. Had I done that back then, maybe I would have come to a non-issue sooner because I think I would have been motivated to use the paddles in Sport mode.

And of course, a couple of you mentioned accidental hitting the paddles when I reported my nighttime incident of gear lag. And I did admit to that.

Bottom line is that the car is running fine and shifting fine. Thank you all for your replies. I will try to be more thorough in analyzing issues before posting in the future.

________________
2010 XK Coupe NA

 

This is something that most of us have done - and it confused the hell out of me the first couple of times, So no mea culpa required - you had a problem you couldn't figure out, you asked, we made suggestions, it's sorted. That's how the forum works: mutual assistance. Sometime you just can't see the problem because you're too close to it, and simply describing it to others brings stuff into focus.

Anyway, glad it's out of the way and you can enjoy the car without worry.

 

This^^ That's why the forum exists. To help each other out.