Noob at a loss on what to do...
 

So here's the story...
I bought a '99 XJ8-L off of Big Iron, an auction site we use at my work to sell heavy equipment, for $2422 a few weeks ago. Car was located about an hour away from me and I was unable to inspect it before purchase, but there were plenty of pics listed plus a video of the car running. I'm finally able to pick it up last Sunday and when I arrive it wouldn't start due to a dead battery even though the seller, and the auction rep, told me the battery was brand new and had been installed within the last month. After a bit of fiddling I was able to get it jump started and loaded on the trailer, however it kept stalling out and was throwing codes. Once home I was able to get it off the trailer, more stalling, into my garage, yet more stalling, and then onto the battery charger and I figured that the low battery was to blame.

Monday after work I decided to take her for a spin to the car wash so I grabbed my scanner and had three codes, P1000 (hey something is wrong btw) / P0102 (hey my MAF has low voltage) / P1144 (hey my O2 sensor isn't feeling well). Start up the car and she sounds just fine so I erase the codes and am left with the yellow reduced performance message. Set off to the car wash and make it about 2 miles from home and as I stop at a stoplight she stalls. Finish up with my wash and make it home with no other issues except for the performance message. Once home I scan her again and am left with only the P1000 and P0102 so I pop the hood to find the MAF sensor plug is melted and deformed a bit. Place an order for an new pigtail and wait for the UPS dude to show up today.

Get home today, install the new pigtail, clear the codes and start her up to find that the P0102 code is still there and she still wants to stall. Call up the parts store and surprisingly they have a new MAF so I install that and the code is still there... My next step is to get a new battery and then after that I'm out of ideas.

So here is what I know... Car has 75k, new MAF and pigtail, supposedly new NAPA battery, fresh 5w-30 oil and Bosch filter, new air filter, and a full tank of what I'm guessing is 87 octane E-10 ethanol fuel.
https://cimg4.ibsrv.net/gimg/www.jag...0875c122ac.jpg
Photo from the auction listing

Forgot to add that she is still stalling after everything I've done.

A compromised battery in these leads to a multitude of issues, that's always my 1st line of trouble shooting. Even if "new" a major drain session can damage the plates affecting charge performance going forward. Have the cell tested, good luck !

+1 it sounds like battery

Any of: badly connected, not new, not charged, damaged due to being flat, etc.

Let's ge the P1000 issue out of the way. You will ALWAYS see either:

P1000 : all engine management OBD diagnostic monitor drive cycles HAVE NOT BEEN COMPLETED
OR
P1111 : all engine management OBD diagnostic monitor drive cycles HAVE BEEN COMPLETED

These are STATUS codes and NOT errors. Every time DTC's are cleared, P1111 will go back to P1000 until the monitoring drive cycles are completed again.

Graham

And a flat battery causes P1000 because the OBD monitors and learned values including fuel trims are zeroed (unset) by that.

Clean the Throttle bore and plate; check for air leaks along the tube from the air cleaner; check wires to and from the ECU (rats); change the fuel filter; put 93 octane juice. Put a can of fuel system cleaner in the gas tank (Gumout, Lucas, SeaFoam, BGK44). What's the status of the secondary tensioners?

Check all cables and grounds. If it is also having starting issues when cold, it may also be a bad temperature sensor, especially since the connector and wires were fried at the MAF.

After done the above (battery check, grounds, and the advice by Jhartz), buy a cheap ELM327 bluetooth dongle, and install Torque Pro on your Android phone (or buy a wifi dongle for an I-phone).
It will give you a lot of info on sensor values (like the temperatures, MAF, CO, etc) without taking them out.
After that, check the live fuel trims for both banks, that will give you an other indication of whats happening before/during the stalling. .

Napa tested the battery and it came back good and I made sure it was fully charged by trickle charging it over night on my bench out of the car. Went out this morning and it was in float mode, so since there were no faults I'm going to say the battery is good. Once reinstalled the same MAF code was there and it's still stalling unless unless I apply throttle.

So the next step is to check all of the areas you all have mentioned and I will report back on the progress.

Thanks for all the suggestions!

The early cars did have Tbody issues -- but ... my guess -- this would have been taken care of years ago. Personally --- I would not try and clean the Tbody.

Sometimes the system needs to have the codes erased more than once -- have had this happen. Erase a couple of times ..start the car a couple of time and make sure no lights. If any lights ....keep erasing. A hard code will direct you to the problem. My guess is you did not need the MAF.

If you actually do think that the car could have the wrong fuel -- that would be the first thing to attempt. Get some premium in there -- mine will not run correctly on regular ... and the computer cannot correct for it like other cars I have.

Also, when in stalls -- does it just cut out or does it stumble and die? Weak fuel pumps are common on these cars.

You don't want to start replacing parts or doing too much .. it's eliminate possible problems.

Functioning of the MAF sensor can be easily checked within OBD2.
I have had problems with the MAF connector for a while, but it did not result in stalling.
Bending the little pins a bit for better contact, and some contact grease, solved it permanently.
Below the sensor values as a guideline.

https://cimg0.ibsrv.net/gimg/www.jag...ad88e456c9.jpg

In my previous 01 LWB I had stalling & a seemingly choking out sputter, it turned out my MAF sensor was severely gummed up with what looked to be melted plastic or tar ?! Cleaned it & the issue was resolved, just throwing that out there as well.

I had some running around to do today so before I left I did a hard reset on the PCM by removing both cables and letting them sit loose for around an hour. When I returned home I reconnected the cables, checked the entire intake system for signs of damage or leaks, checked over the throttle body for signs of bad wires, and just gave the entire engine bay a good once over. Hopped in the car let the system do its self check for around a minute before starting the engine and the same codes popped up. It was in the mid to upper 50's today and the car didn't stall while sitting at idle for around ten minutes so I took it out for a little spin to see how it reacted. At minus 50% throttle while driving it will get up so speed with no issues at all, but if you give it 50% or more it will stumble and act like its not getting any fuel.

I picked up a new fuel filter and will install that once I get home tomorrow. Also here are some pics of the car so you can see what I'm working with.
https://cimg0.ibsrv.net/gimg/www.jag...8de4b1d230.jpg
https://cimg9.ibsrv.net/gimg/www.jag...aad2a8b65f.jpg
https://cimg1.ibsrv.net/gimg/www.jag...2687962b69.jpg
https://cimg8.ibsrv.net/gimg/www.jag...2b94314fa3.jpg
https://cimg2.ibsrv.net/gimg/www.jag...88b6494081.jpg
https://cimg6.ibsrv.net/gimg/www.jag...e75a0057ab.jpg
https://cimg7.ibsrv.net/gimg/www.jag...6643b2fb34.jpg

I had the same problem when I first bought my last 308: cleaning the throttle body and plate worked. Might also examine the throttle cable for too much play. But once you have the fuel filter in, and the problem is still there, look to renewing the fuel pump. Problem sounds like a fuel starvation problem.

It seems a rather beautiful car from the outside, and the interior will clean up nicely with some hours of elbow grease.

But I really advice you to approach this pragmatic, measure systems and check their values before starting to just throw money at it.
Fuel pressures can be measured easily, and so can most of the other systems and its components, and most info of how they should read is available here, or comes up with a simple Goggle search.

On the v8 X308 there are 2 TPS sensors in the same assembly , one that goes to the engine ECU and the other to the transmission ECU and both will read 0.50 volts DC at idle

See page X :

This can be seen with the engine not running but the key to the on position

The battery cable clamp can stretch over years and cause problems as well as the fuse link just after the battery having terminal nuts on the fuse coming loose is common

There are battery shims at the parts store to address a loose battery terminal

Editing

I wrote some detailed stuff a minute ago but my (^#^$( Ford computer dropped it out , so I'll try to edit and put it back in in the morning

So now that the Holidays are done and work has settled down, I was able to dive into my P0102 MAF issue. Since I switched out the MAF pigtail, have referenced the wire colors from the old plug vs. the new one and everything matches up.

When looking at the plug, with the clip at the top the colors are as follows from left to right; WU (White/Blue), BY (Blue/Yellow), GY (Green/Yellow), UP (Blue/Purple), and BG (Black/Green). With the key off the BY and BG wires look to be my ground, so I just need to figure out which is the constant hot with key on, and which is reference when the car is running. Does anyone know what values I should be seeing?

First off, bookmark this link... JagRepair.com - Jaguar Repair Information Resource
Next, if you have any corrosion on the battery cables, replace them, you will not be able to clean them and the corrosion will prevent proper voltage output and proper operation. Be sure to check your alternator for proper output also.

From your description in post #13, it sounds like the MAF isn't connected and your in default mode. This mode gives you the ability to drive the car at a minimal rate (as you describe the 50%) to either get out of trouble or get home to solve the issue. I would disconnect the nifty new pigtail and see if the performance is the same. If so, you know you may have to dig deeper into the wiring for another break. But, you can meter the pigtail and if its above the voltage indicated below, you simply may have a bad MAF, ..albeit a new one.
Causes: Metered diagnostic:
A MAF V PID (MAF PID) reading less than 0.23 volts in continuous memory or key ON and engine running indicates a hard fault.

I attached a couple pdf's also...one shows what should be your TB, the other is an electrical troubleshooting guide for which you've done a couple of procedures already. But its good to have.
Here's a link from the JagRepair link, it was too large to upload. Its the electrical diagrams for your car with color codes listed... http://www.jagrepair.com/images/Auto.../jagxj1998.pdf

I have never seen any electrical values for the MAF wires, but the below are the flow values you should read for a N/A.
They fluctuate some +/- .2, but in my car they are pretty spot-on (after having had connector issues for a while).

https://cimg5.ibsrv.net/gimg/www.jag...5a37faf2a3.jpg

The value for the return wire is 0.50 volts DC at the correct idle speed , this with the connector installed so the sensor is powered with the reference voltage

There are 2 return wires , one for the engine and the other for the transmission ECU

See page 16 for wire colors and 40 for a 1999 , later years have a different wiring harness with differences

http://www.jagrepair.com/images/Auto.../jagxj1999.pdf

The 2 return wires are the blue and the other wire green , which should be the middle 2 wires on the connector