Finally resolved P0176 / Check engine light
 

2002 XJR with 102,000 miles - This saga went on and on, and sometimes it would include the code for the other bank. The shop checked for vacuum leaks forever, including replacement of two O2 sensors which actually didn't fix the problem, keeping the car forever and charging me proportionately for it.... We then followed the tips from a forum fellow to just concentrate on the MAFs issue by first try giving it a good, careful clean up, which we did and it did fix the problem for some 100 miles and a couple of weeks at which point the check engine light and the code(s) came back. However, I should add that during this short period, something kept telling me that it was not actually working right.because, upon WOT, it accelerated only like my old '98 XJ8 and not like an XJR, meaning that the power wasn't there because the AFR was still not right. To my luck, here's when I got my DMV annual registration notice, which this year includes "Smog Certification". I decided to do one more test before going for a replacement MAFs. I did the cigar test, for which I did not use any of the more expensive stogies, but it gave me results anyway... I uncovered the throttle and put a plastic bag to seal it, tightened wit a rubber band. I then pulled the line from my electronic boost gauge sensor and blew very dense smoke in it, creating good pressure that I could see on that significantly inflated plastic bag. Never saw any smoke from any vacuum juncture or hose or anywhere. Did this several times within three days and could not see any smoke, I guess only confirming the shop report of no leaks.

So, the replacement MAFs was the obvious thing to do, but I didn't spend over $300 on a new one. I got one from eBay from a 2003 XJR that died at the young age of 35K miles. Price was only $120 which was just right. I wasn't about to put a $65.00 MAFs with 100,000 miles or more on my XJR and risk having the same problem back again (BTW, my XJR's MAFs died somewhere over 102,000 miles). I did not erase the codes, yet, after driving some 15 miles, the check engine light extinguished by itself and it has not returned so far, even after driving about 300 more miles. This week I'll have it smoked. I sure hope that my 102,800 miles spark plugs won't be a problem (Comments on the plugs? Thx).

I would change the plugs.

According to the Jaguar maintenance sheet, the spark plugs on SC engines should be replaced every 30,000 miles. Iridium plugs should bi fine for some 50-60k miles, I guess.

https://cimg7.ibsrv.net/gimg/www.jag...c7ac911f69.jpg

Thank you both of you guys!
I'll proceed to replace the plugs..
Before I jump in, is there one or two particularly tough to get to that you know of?

Cheers,

Well, didn't have the time to replace the spark plugs but it passed the smog, anyway.
But at 100K it's time to do it, regardless, so I will order them this week and get them changed.
Cheers,

I've just read this once again today and I need to correct the post because this was actually just the beginning of a major smog catastrophe for my 2002 XJR coming up. The car had no codes and no engine light and the smog guy said everything "passed", except for one small detail... the CATALYST MONITOR was failing to initiate.and that, he said, was enough for him not being able to clear the smog report to Sacramento. The catalyst monitor was the only one of 11 diagnostic checks of specific emission control component monitors that was not yet initiating the monitoring of the catalytic converters and without this happening the car is not yet smog "ready". I later learned that, because I reset the ECU after I replaced the MAF sensor, all of the IMS readiness monitors were shut down and needed to be re-started again by the ECU, and they all did initiate with the exception of the catalyst monitor. Learned? Yes, learned to NEVER reset the ECU, or disconnect the battery any time in the proximity of the new registration due date, as in smog due date.

I tried the drive-cycle that applies to the 2002 XJR several times with no good results. and the new registration due date was getting close, so eventually the car could no longer be driven on CA streets. So, I took it to this British car specialist in our neighbor city, Carlsbad, a British fellow who has the 25-year old shop full of Jags, Range Rovers, Bentleys and Rolls'. He said that he's familiar with everything that affects this condition on the car and that he has all of the necessary equipment/testers that pertain to my car. By now, he has changed several items, including a new battery, two new catalytic converters, plugs, etc. He assures me that, at this point, every piece that may affect this condition has been addressed and that the car is now running 100 times better than when I brought it in. BTW about six months ago and before I replaced the MAF sensor (which fixed the engine light), two oxygen sensors and the EGR valve had also been replaced..Well, my XJR has now been in this shop 4 months and, supposedly everything works beautiful, except that..uhh . . . the catalyst monitor still fails to initiate after doing the drive cycle a whole bunch of times through at least the last two months ... Unbelievable...

If anybody here who reads this post may know something that may have not been addressed about this, or may know somebody else with more knowledge and experience on stubborn IMS readiness monitors I would immensely appreciate the help. Thank you