History on this car. EDIT: car is 99xk8
Bought it about a year ago with a bad A drum. Repaired the A drum along with new Transgo pressure valve. About 6 months ago replaced secondary tensioners, thermostat and tower, new hoses, and new cam cover gaskets. This was my car until my daughter had problems with her car and I have been letting her use it the last three months.

Two days ago my daughter calls me and tell me car won't start when she came back to it after shoping. Got to car tried to start and it would run for a couple of seconds and then die. While running for this short period I tried to give it some throttle and had little or no effect.

Check fuel pressure at schrader valve and fuel came out under good pressure. I didn't have a gague with me. Gave everything a look out and didn't see anything stand out.

Check the oil and it was low. It took roughly 1 1/2 - 2 quarts. The car started right up and ran fine. She drove it around 20 miles that day with no problems . Latter that night while on the freeway it stalled on her. Got to her and it acted like it did earlier in the day where it would start for a couple of seconds amd die. Had it towed.

Look at it today for first time. It has no codes stored but had P0171 pending. Did visual check for vacuum leaks or anything else. All I found was that the wire for the downstream bank 1 O2 sensor wire was laying on the catalytic converter. Moved wite got in car and it started right up. I let it idle for about 20 minutes. Checked codes and nothing had changed. I cleared the codes and took it for a quick drive up the driveway at my shop. Car ran great and has great acceleration. Just as I was coming back to the shop it stalled again. Checked and no codes stored or pending.

It's raining pretty good now so will wait til tomorrow to work on it. Will check to see what the actual fuel pressure is.

Like to have input on what else I might check

 

P0171 can be caused by several things from air leaks to restricted fuel but your descriptions of events has all the indications of a failing TPS (Throttle Position Sensor) on the Throttle Body.

Graham

 

Start with the recent faults and causes of them.

E.g. why was it low on oil let alone so low?

E.g. is that O2 cable OK and why was it where it was?

 

I'm with Graham. A car that doesn't like to run and doesn't have codes is a good indication of tps trouble.

 

Thanks Graham, I going to check fuel pressure first. I have a spare 99 throttle body that I can try. But if it was TPS would it activate the check engine light or at least give me a pending code wjen it stalled the last time?

Thanks Jagv8,
Low oil: I have been working oit of town quite a bit in the last few months and 2 trip to North Carolina, plus my daughter has had it and I have rarely seen it. I know that is no excuse but I let my daughter it needs to ne checked at every other fuel fill up. The reason why it was low I'm not sure. It has no major oil leaks. I will look it over when I get this problem solved. Is it possible it could be bad valve stem seals that could of dried before I got the car because it was sitting for 3 years before I got the car?

O2 sensor wire: no noticable damage to wire. The sheathing was not melted. I had transmission out for A drum repair. Wire was not near cat when job was completed. Could of worked itself that way. I should of zipped tied it to keep it clear. Learned from that error will make sure it doesn't happen again when doing transmission repair

 

You're doing the right things, especially for a car that sat (nudge the girl more, though).

A loose connector (or chafed wire) might cause a stall and unless it's repeatable may be a swine to find, sadly. Also if it doesn't do it often and in similar circumstances it won't have much chance to throw a code. So don't beat yourself up if it takes a while to figure.

 

It's a process of elimination. There's no absolute single cause of the original P0171. Here's the list for reference:

1. Engine misfire
2. Air intake leak between MAFS and throttle
3. Fuel filter, system blockage
4. Fuel injector blockage
5. Fuel pressure regulator failure (low fuel pressure)
6. Low fuel pump output
7. HO2S harness wiring condition fault
8. Exhaust leak (before catalyst)
9. ECM receiving incorrect signal from one or more of the following components: ECTS, MAFS, IATS, TPS

As I recall with a failing TPS on my 2001 XK8, it didn't always set a code.

You wrote that it was run very low on oil. Is there a chance it was also run low or even out of fuel? This can drag sediment etc out of the bottom of the tank into the filter.

Graham

 

This is a 1997 model, all the sudden it is shutting down on the HWY (that is scary) and when it tries to run there is little to no throttle response. Then it will run, then it will do it again. I would check the TB stuff people are saying here but I would next be looking at the ECM. They are well known for being a issue for the 97 models. At some point if you can't get it to run I would have it sent out to ASI to be bench tested and repaired if needed.
My 97 ran the same way your is. Shutting down, no throttle there when it is running for a few minutes then shuts down. Put 3 diff TB's, same issues. Put the orig back on it after the ECM was found to be bad and it was fixed and then the problem went away.

 

Thanls to all for your responses. Think I my have figured it out but driving it for a while will let me know. This is the testing process I use today after it finally stopped raining.

Installed pressure tester on schrader valve. Started the car, it has always started from complete cold start.
Fuel pressure about 35lbs. Let it idle for 15 minutes. Turned ignition off and tried to restart. Would not start and I had zero pressure. This is pointing to fuel dilvery problems. Let it set for 15 minutes while I checked jagrepair.com for location of fuel pump relay, thank you Gus. Got a spare relay from one of my parts cars and tried to restart car before changing relay. It started right up with 35lbs pressure. Let it run for 5 minutes while I cleared the trunk of my daughter's crap so I can have acess to fuse box. Shut car off, upon trying to restart a first with key in on position I had good presssure. When turning key to start the pressure went to zero and car started for a couple of seconds like mentioned earlier and then died. Tried to start a few more times and nothing.
Replaced relay with one from patrs car and it started right up. The relay I took out was warm. The car has started every time since switching relays. I'm going to drive the car a bit today to see if problem occurs again. If it does I think it would have to be fuel pump. I think it would be strange for a pump to work sometimes and the fail at other times.

Driving today with fingers crossed.

 

It appears you have it, but pumps have had intermittent failure. The fuel pressure regulator is also a possibility.

 

^^ Fuel pumps have indeed sometimes failed intermittently before finally giving up the ghost....

Changing the fuel filter can help to keep these fuel pumps from having to work so hard to push fuel through a heavily-clogged filter. I changed my wife's 2006 XK8's fuel filter at 90,000 miles and should have done it much sooner. The fuel that ran out of the factory filter once I removed it was a murky grey color. I learned my lesson and will change the fuel filter every 40,000 to 50,000 miles going forward. The Motorcraft version is a $15 part from amazon.com with free shipping. Well worth the time and money if it helps to ease the strain on the fuel pump....

 

The relay replacement seems to have solved the problem. In the last couple of days it would start cold, but would not restart after being run for 15min. This morning it restarted several times after being warm.
It was nice to drive my car again after 3 months. Now I will let my daughter use it until she gets another car. Told her to stay off the freeways for a couple of days to make sure problem is solved.
Thanks to all for your suggestions.

 

Hey BobRoy!

It's nice to "hear" from you again. I was posting my problem and scrolled down to see your problem. Mine is similar to yours. My car has been so reliable this caught me off guard.

The relay idea sounds like just my speed if that's my problem. Can you give me more information about which one you replaced?

 

Posted a reply to your thred to keep discussions about your car together to prevent confusion.
https://www.jaguarforums.com/forum/x...-after-174901/