Do you notice the idle is a bit gruffer than usuall?
I have the same symptoms to a tee, could one call the choking a bogging in other words?
Sorry for the thread Jacking Kinda clung to your symptoms!

 

No problem..Fox Box...lol....Yes you are spot on !!! It is a little rough at idle. And it does seem as the though the car is bogging down when you try to accelerate.

 

Is it a dead miss or just weak? The injectors are just above the edge of the valve cover, intake side of course. You can listen to the injectors with a stethoscope and see if the one in question is dead or sounds different from the rest. You can also check the electrical connection for damaged terminal, they get brittle and if someone had it off the lock tab likes to break off and cause bad connection. Otherwise you could stick a noid light in it and make sure it is actually getting pulse from the ECM. No pulse, no fuel, no sound no fuel, compression on that hole is good?

 

I had a diagnostic run on the vehicle. I was told that the number 5 cylinder wasn't firing properly. Possible bad plug or coil..I'm guessing plug since I believe I changed the coil.

Is the number 5 cylinder on the passenger side of the block...second from the rear plug? I just want to make sure before I start taking covers off.

 

Bang on, read further down that your gonna pull valve cover to change #5 plug? All we pulled was the 'pretty cover', the rest was just coil, then plug!

 

This is strange, I just looked at the cylinder numbering for a 4.0 and this is what it said lol where is number 5? on the 2002.5 and up the 2nd from rear on the pass. side is #5, but apparently a 4.0 does not have one.. When you figure out which one it is, I would start by changing the plug. Then if no luck, try switching the coil to your number one and have it re-diagnosed to see if the miss jumps to there.. Then if that is to no avail, try swapping your injectors..

"Always start with the easiest possible cause or the issue and work your way up to the most difficult.." Eric lol

 

I'd go with a dead miss 'cause of the effect of pulling the coil wire off, I will have a listen at the injectors, and pick up a noid light at Auto Val. Problem is I enter the equation after the VCG was done by another above average mechanic (drivers cover is a b**ch I hear), and symptoms started after the fact... I will have a good gander at the injectors today and post some findings!

 

OK I've got the Jag back to its full potential.So glad to have the cat back!!!! The schematic listed above, I have discovered isn't correct. Actually the Jags up to the 2002 models have a different firing order. number 5 cylinder is the first cylinder on the drivers side in the front of the engine. It goes from there 5, 6, 7, 8. The left side firing order is correct.

Replacing spark plug and Coil #5 along with the Idle assist valve...has the cat running better than ever.

Thanks for all the help guys..I really appreciate it!

 

Fantastic to hear!

It must be the day of the Jags, our issue was in fact the injector not being connected at all, gotta love the guys that break the connector off the injector, and don't even put it back on

My friend is also back to normal again

Thanks again guys for all your help!

Joe

 

hey, guys i had this problem too with my s-type. at first the stuttering was not bad but after a while it got really worst. i have changed coils, injectors, spark plugs, fuel pump and even bought a new throttle body. after installing all those parts. the problem was still there. low and behold it was really the Mass Airflow Sensor (MAF). These cars are really good cars but it takes alot to maintain them. im glad i got mines fixed cause i really loved that car.

 

I had this exact sounding issue on another vehicle (not a jag) and blamed the transmission but inv the end it turned out to be a coil pack. Coils are quicker and easier to diagnose than a transmission.

Good luck with it and hope you solve it..