I recently bought a 2003 XK8 4.2 with 159,000 and had been neglected by previous owner.The car ran sluggishly when i bought it but I put the hesitation in acceleration down to the no knock sensors which did in fact show up on my computer. 1 or 2 other codes also showed up including a misfire on #4 cylinder so I set out to replace front suspension plates and misfire before removing manifold to replace the no knock sensors. I found a bad spark plug on #4 and replaced it but now the car will barely run and shows 12 codes (8 showing a misfire on every cylinder and P1313/4/6)
I thought catalytic converters may be plugged so removed egr on drivers side manifold but had zero effect.Car seems to idle ok although hunts without stalling so I wondering if this is fuel related. I would value all opinions so I can devise a step by step plan to eliminate all possibilities. Sorry this is so lengthy but it seems like a question for the experts.

 

first and foremost, buy a NEW battery. My '02 XKR was showing several codes, and occasionally a fail safe warning. The battery was strong enough to start the car, no problem, but the voltage was not enough for the computers to operate correctly.

Since putting in a NEW NAPA battery, no issues with false code reporting.

These cars must have a strong battery or your ownership will be miserable. And keep the battery on a battery tender when the car is not in use for a few hours.

Z

 

 

With that many miles and heat cycles, those wires at the plugs could be very brittle and cracked when you moved them.

 

I paid $2 for voltmeter which seats in lighter receptacle.

 

I bought one of those too. But I might have paid more for the 2 USB charging ports that it has..

Z

 

OK just a piece of advice, I learned this the hard way myself, never buy an abused luxury or performance car. They are money pits. (I bought an abused XKE, it nearly broke me). You'll put a tone of money and effort into the thing you'll never get back and chances are it'll never be right.

 

+1 .... but too late for revitup.

Good advice from zray on a NEW battery. Partially discharged or failing batteries are the most regular cause of weird electrical and electronic faults on this era Jaguars.

Check for good fuel pressure BEFORE suspecting individual fuel charge/delivery components.

Graham

 

It's been said many times before, buy the best example, because in the long run … Battery, clear the codes and work through them. No knock sensors ? I didn't think you
needed to remove the intake manifold to replace them.

 

Many thanks to all in particular zray and enderle for actionable advice.
I cannot afford an E-type but believe me I would work on it every day broken or not. My attitude to this car is that "bad buy or not "it needs to be fixed and of course dumping it at the dealer is a precursor to bankruptcy I agree.,
No, the car ran with issues when I bought it but now very very poorly so my instincts suggest something has suddenly happened (as it does with many Jags) and a few of the right tests and experiments will hopefully restore it to reasonable performance.

 

Sorry enderle I meant GGG

 

Step 1- Compression test
Step 2- Fuel pressure test
Step 3- New Battery
Step 4- Clear codes and hard reset

This will give you/us a baseline to work with.

 

Thanks Mr Snyder. Working on battery now with an eye on fuel pressure check next. Rule of thumb on compression checks out, but will revisit if no luck. Just a little concerned the Prince of Darkness might be messing with ECU

 

We get quite a lot of posts about poor running and suspecting control modules that eventually turn our to be other causes. The modules are more robust and reliable than you may think. Not to dismiss it as a possible cause but you can put it down the priority list.

Graham

 

Fuel pressure is available over OBDII on these later cars. Get a cheap ELM327 wireless reader from eBay/Amazon. Will pay for itself many times over. Pressure should be a pretty solid 55psi at all times.

Check the fuel trims, too for a general health check. Will tell you about air flow meter, air leaks and possibly fuel starvation. Possibly evap problems, too.

Definitely focus on everything fuel related (fuel filter!). Clean everything now, these fuel pumps are EXPENSIVE and hard to replace.

Also, put all 4 of the oil cooler lines on your radar. They see oil pressure (all 4 of them) and are past their expiration date if original. Budget about $400. If any one burst, you lose oil pressure instantly and will be stranded at best. Worst is a seized engine.

Best of luck, keep us posted.

 

Can we assume the fuel tank was drained and replaced with fresh fuel?

 

Thanks Fmetz and Brobin. Dragging out the tank seems premature at this stage although as you assume we do not know how long the car was stood. Fuel pressure guage is next on list and Fmertz 55psi is what I am looking for. Don't know what fuel trims are, and does this car actually have an external fuel filter I am a little surprised that the misfire on every cylinder code (which are plainly fake news) has not brought comment.. Just to recap. Cart was running 6 out of 10 at point of sale; zero miles later with only suspension plates replaced much much lower.

 

I'm just thinking that if the fuel has gone bad it could explain a lot. No need to pull the tank. You can use a siphon pump down the filler tube to remove most of what's in there and then put in a few gallons of fresh fuel to see if it makes a difference.

 

There is a fuel pressure sensor already, at the end of the fuel rail, passenger side. You can get the pressure reading with a basic scan tool (this is standard OBDII, not proprietary Jaguar). That sensor is already in reference to the intake pressure, so it should read a constant 55psi, under all throttle positions.

 

Thanks again. Brobin i am more worried about gunge blocking fuel pump in tank than bad gas which often has a tell tale smell. To my mind a blockage would make sense as the car was moving and gassed up. Either way a fuel pressure check should point the way. Yes thanks Mr Frmetz I did find the valve and thought to see if I can rent a gauge from parts store as I am not sure how to implement the scanning route. I do have a small hand held scanner that alternates between showing "no link" and then all these 12 codes. I don't know if that is relavent info but I confirm it has nothing to do with a secure connection. I will report f p reading when I get it and thanks again Gentlemen for your helpful insights.