A few hours after getting a full tank of gasoline about a week ago I drove it down to tire place for an alignment. They could not do the alignment because the car could not be driven into the bay. All of a sudden my 2001 xk8 would start and then die, I had it towed home. I cleaned the throttle body, used new gasket when reinstalled throttle body, cleaned the MAF, and no change. I added some methanol to clear out tank of any water. Tried disconnecting the MAF, no real change. There is pressure in the fuel line.
Pulled the injectors and sent them to Dave in Jacksonville, all tested excellent and reinstalled in car yesterday.
It will start normal for 2 seconds then drops to 600 rpm rough idle, shaking the car, then in about 10 sec it will die. I can get rpm up to 2000 by pumping pedal and then engine is smooth. No codes.

So today I pulled the valve covers. Everything is fine, all cams line up, no oil in spark plug holes.

Any suggestions?

 

Maybe an air leak somewhere after the MAF, check the plastic inlet hose for cracks. With the pedal pressed the engine keeps running?

 

with pedal pressed the engine runs well at 2000 or above
I will inspect for air leaks.

No cracks found in air pipe.

I will rebuild after I check all my valve clearances. I have one tappet noise for about 2 years since I did a heads off valve job.

 

I do not have tool to adjust valves insitu, so I am reinstalling all parts and see what happens.

 

Mine did similar. At times, while driving, it would just stumble and go into failsafe mode and it would only go a few miles per hour. Very exciting when driving in traffic. Other times, during first start of the day, it would stumble and sputter and die. It would only start if I pressed the throttle about half-way and held the RPMs up to about 2K until the temp gauge started to rise. In my case, after the car warmed up it wouldn't do it again for the rest of the day.

I would get occasional codes for TPS issues. Replacing the TPS seems to have completely fixed that problem.

These symptoms, after a fill-up, are classic symptoms of a faulty purge valve. But it shouldn't happen again until the next fill-up if that were the problem.

 

TPS?
where is purge valve and what does it do?

 

TPS = Throttle Position Sensor. Located on right side of throttle body.

The purge valve thing was pure speculation. I don't know if the Jag is susceptible to that problem, or not. Many cars are. Regardless, fuel gives off vapor. In the olden days that vapor would vent to atmosphere. The smog ***** put an end to that. The vapor now goes through charcoal canisters, and then to the engine's intake. The purge valve essentially "purges" the vapors from the canisters and combines them with the engine's fuel mixture, to greatly oversimplify things. I have only experienced it after fill-up, and never again until the next fill-up.

 

How do I check it out? Is it inside the chamber or the black part attached on the outside?

 

It's the entire piece. In my case, I pulled the connector and sprayed contact cleaner on both connectors and that seemed to solve the failsafe issue. The cold start thing also became very rare, but didn't go away entirely. I eventually replaced it and that seemed to fix both issues. But I was also chasing other problems and wound up replacing the entire throttle body with a used unit, which also had a replacement TPS.

The only way I've found to test was and OBD II scan tool that showed TPS %. My old one seemed to be rather inconsistent at idle. I got the replacement from FleaBay for about $40 and it seemed to work fine.

 

unplug the throttle motor. it’ll be declutched at default position and mechanically connected via limp home lever

 

should it idle better when I unplug the TPS on the throttle body?

 

which plug do I pull on the TB?

started up and even worse now, difficult to increase to steady rpm above 2000

I disconnected the MAF and it is much better, but still drops idle to 600 and gets rough

there is a whine coming from the engine TB area with key on, what is that?

 

The connector for the throttle motor is the one in your post #8 pic with the green and red wires.

My TB makes a noise from the throttle motor with the ignition on, although it's more of a buzz than a whine.

 

I unpluged that red/green connector and MAF disconnected. rough idle up and down 900-1200. FAILSAFE ENGINE MODE
Reconnected MAF. rough idle around 700 FAILSAFE ENGINE MODE

 

maybe it is the purge valve. and a YouTube says I can check the function of the valve by disconnecting line to charcoal cannister
which line goes to the canister. ?

 

anyone know where the canister is located on MY2002 xk8

 

I taped off the hose to the TB from the purge valve and still rough idle and stalling. I continue to smell gas fumes around the car, the car is running fuel rich?

what is next. injector controller?

 

grandson is here this weekend while my daughter goes to dead concert
next week I think I will try to empty most of the gas from the car and see what happens

 

It's underneath the left front fender liner, at the back. You'll need to remove the wheel and fender liner.

 

oops. I meant 2001 xk8.