I have switch new coils on and the misfire still occur. just changed the spark plugs with jag oem, and the check light engine hasnt gone away nor the restricted performance on the dash. Can the cats really cause misfires? Or i might just be missing something.


JAGUAR S TYPE R 2006

 

no your miss fires are causing bad catalyst efficiency.
normally , at least for me and one other forum member that i know of ;
a blocked cat will cause pinking not miss fires and with no codes .

and a burnt out cat converter witch will happen if you keep driving the car ,
will rattle like there are rocks in it . as the core breaks up

you need to check your fuel trims , and check your maf sensor is working properly .
id suspect a major vacuum leak. but your fuel trims will tell you if your rich or lean .
go from there .
to do this you will need a scanner . you can purchase a elm327 of ebay or the likes very cheep .
and load an app like OBDCAR DOCTOR or TORQUE on to a smart device to read it .
if you have an iPhone/ipad you will need a wifi elm327 .
if you have any other smart device (android) you will need bluetooth elm327.

 

I keep hearing fuel trims mention what are they and we're are they located.

 

before the misfire it was only the catacatalytic converter code

 

watch this .


your cats may be toast already .
you need it running on all 8 to test via temp checking the cats .
or literally look in side them .

 

On an R even an elm327 can read fuel trims. $10 or so.

 

THIS youtube link should be in the stickies. No way to thank you enough.

 

So now the car is leaking water by the cats and transmission, seems like some hose up above

 

Is it coolant , or water from the air conditioning drains ?

 

You have the "R". Do you know about the under SC hose?

When that hose leaks it usually comes off the back side of the engine. You should be running Dex-Cool so will have red stains.
Are you losing any coolant?

Can you see any stains? Yes you will need to get under the car and look.
.
.
.

 

the water leaks start when the ac is on so I think it's probably from the account, but recently it started leaking also from the other side. its water no color. there is also a hissing sound coming from around the supercharger like a air leak.

 

You will need to completely (i.e. 100%) fix any air leaks.

 

Just went to my local British car service
They told me the car was sucking a lot of air. that's what the hissing noise coming from the pcv hose. they say I need to change the fuel filter ,clean the injectors, and they are going to program the system so it won't suck in so much air. they said that is going to take care of the misfires and restricted performance. they quoted me 570$

 

They also told me they couldn't check the catalytic converter or the o2senor with taking it off and checking inside.

 

Overpriced, wrong fix. Cats can be checked several ways. Go elsewhere.

 

There is no way to program the system to not suck as much air??

If you have a vacuum leak you MUST get it repaired. You have a physical problem.
.
.
.

 

+1.

There's no indication that the injectors need cleaning. Sounds like your shop is just making (bad) guesses at the expense of your pocketbook.

 

 

well they said I didn't have a vacuum leak. but you can hear a hissing coming from around the pcv hose

 

what they quoted me for is going to take care of the misfires and restricted performance is what the guy told me