Hi Guys,
I noticed today I have a sort of a stumble under WOT between about 4000 - 5000rpm. Recent maintenance includes new K&N airfilter, changed supercharger oil & left bank value cover gasket.
Also removed the exhaust back boxes which has given a much better sound.
I'm suspecting spark plugs or coils?
Opinions very welcome.
Thanks in advance.
Jeff

 

On the 2003 supercharged model there are 2 ( ? ) fuel pumps and the second one is commanded on at 4000 . Check the fuse and swap relay first . If it's only 1 swap the relay as it may be pitted causing lack of current . Fuel filter ?

See page 51 below

http://www.jagrepair.com/images/Auto.../jagxk2003.pdf

Hope this stops your spot of stumble under the bonnet .

 

Jeff390, It would be easier to help if we knew what the details of the vehicle are. You can use the USER CP and add that info to your signature line and it will always be there. We don't know whether you one or two fuel pumps, one or two ignition amplifiers. Whether you throttle is cable or electronic.
All of these can be determined with the model and year.
Get back to us with the info and we can help you resolve your issue.

 

Good point, though the OP mentions supercharger and with luck is in the right forum

 

I would suggest checking the MAF.

 

Post #2 looks promising

 

Jeff,
Are we correct in assuming that this is occurring while in gear on the road rather than engine limiting while the transmission is in "Park" or Neutral"?

 

Hi Guys. Thanks for the feedback. Will update my user info as soon as I figure out how. Car is 2003 XKR convertible. Would a failing spark plug or coil pack cause such a stumble? Was also wondering if I should have done a hard reset after fitting new airfilter etc?
The problem happens while driving, and is relatively new. I wll check fuel pump relay. Also noticed that someone has slammed the hood/bonnet breaking the plug that goes into the MAF sensor. All wires appear to be intact though...
Any other ideas on isolating the problem?
Thanks again.

 

See post #5, posted before you made this comment.

 

There is normally no way to slam the hood and hit the sensor. It means the whole air filter fitting has to be revisited. The air box is likely sitting too high. If the sensor is broken, there is likely an air leak, so it is not a good start. Fortunately, these sensors are very inexpensive as they are used on TONS of vehicles. I would start the investigation there.

FWIW, assuming the 2003 XKR in your country is the 4.2L fitted with the ZF 6HP26, the fuel system is return-less with just one pump. You can check the fuel pressure over OBDII. Should be a constant 55psi, and not drop off at high rpm. If you get a cheap ELM327 and a phone app, you can record it, and keep your eyes on the road...

Best of luck, keep us posted.

 

[QUOTE=fmertz;1850148]There is normally no way to slam the hood and hit the sensor. It means the whole air filter fitting has to be revisited. The air box is likely sitting too high. If the sensor is broken, there is likely an air leak, so it is not a good start. Fortunately, these sensors are very inexpensive as they are used on TONS of vehicles. I would start the investigation there.

Thanks for this. I will look into the MAF. Will also post a couple of pics showing how/where the plug appears to be hitting the bonnet.

 

The MAFS did have some slight build up. I cleaned and reinstalled. Can't test it yet as I'm also in the process of replacing the lower control arm bushes and ball joints- a hell of a job! Will try and attach pics of where bonnet appears to be hitting the sensor.


Someone suggested airbox was sitting too high. All looks perfectly mounted

 

In your second picture the air box mounted appears to be broken free and sitting up a bit to high for normal.

 

Your MAF connector is cracked. So I hope the pins are making good contacts.

 

You could run it remember what it sounds and feels like. Disconnect the MAF then run it again. If it sounds the same then the MAF is not doing what it should.

The air box mounting is obviously broken. £1.50 off Ebay, if your in UK. $2 in USA?

 

Hi Frank. You're right the rubber airbox mount is broken. I'm in N.Z. I spent ages looking in ebay.com.au but couldn't find the replacements you mentioned. Do you have a link I could use, or are these parts (or similar) available elsewhere?
Thanks Jeff.

 

Will take a look for you

 

Here you go. I cannot remember the measurements of mine but they should be one of these. https://www.ebay.com.au/sch/i.html?_...bbin+&_sacat=0

There are two basic shapes. Straight sides and 'hourglass' shape. Ours are the hour glass shape.

Just noticed something too. Most them come from UK! Will ask someone over here if they know what size and type. Many times I have ordered stuff from your side of the world and its arrived very quickly. I am sure the reverse is true too.

Be right back! (again) I shall have to await a reply from my friend.

 

Lots on Ebay if you search for EAC8130

Could also try here as these have been used in Jags since the 1960's: Rodney Jaguar Rover Spares Ltd

 

This might help too: https://www.jaguarforums.com/forum/x...unting-181169/