Hi all...

I have a 2002 x-type 2.1 V6 that is misfiring. Although misfires appear to be common on the X-type, I seem to have an unusual issue. The car develops a misfire at set points, pretty much everytime the car hits 70mph, and or 3000rpm going up hills (fine when accelerating on flat or downhill). So far I have replaced the coil packs, spark plugs, inlet manifold gaskets, and PCB hose. Potential air leaks checked for. Compression test. injecters checked. The car has been extensively diagnosed at a local garage with a diag machine attached while on test runs at the points of the misfire. graphs show all sensor readings at the failure points are within Jag tolerences, fuel trim levels and the fuel pressure is excellent. The mechanic can see no valid reason for the misfire and suspects a potential ECU fault? Car works absolutely fine if kept under 3000rpm or 70mph.

Codes that have flagged over the last couple of months are

P0300 - Random misfire
P0301 - Misfire cylinder 1
P0303 - Misfire cylinder 3
P0304 - Misfire cylinder 4
P0306 - Misfire cylinder 6
P1642 - CAN failure
P0402 - Bank 1 CAT efficency below threhold
p1582 - Flight data recorder

More recently i just get the codes for cylinders 1 & 3

Any help would be greatly appreciated as im now pulling out whats left of my hair

Cheers

Daz

 

1) Check if there is water leaking into the engine - usually from the water jets on the hood. My car was experiencing the same misfiring and occasional jerking and my mechanic found some water in the engine.

2) MAF sensor.

 

The 3000RPM figure suggests the engine is being put into Restricted Performance mode to prevent further problems. As a start point, check the crankcase breather hose line that goes from the cambox cover nearest the radiator to the inlet manifold - it's about 1 inch dia. Splits on the underside of this hose are common causes of misfires. You might have to take the main plastic engine cover off to get full access.

 

Do any of these code descriptions help to further identify what the problem may be?

 

@Astro yes that pipe has been replaced. Also fitted new MAF, still no change. Having spoken to the mechanic and a Jag Specialist in Sheffield, odds are its a collapsed or restricted CAT on that bank and its the back pressure under load causing the Misfire.. Hopefully this will finally resolve the issue as i think i've replaced just about everything else i can...

 

NJD: had the same type of problem with misfire, my mechanic had me pull the upper O2 sensor, lay it safely on the intake while it's still connected, then go for a little drive... mine drove great, held revs at 5 grand for an entire block (kept her in 2nd gear) this demonstrated that it was indeed a restrictive cat...
Best of luck
Gary

 

Hey mate, just a quick question. When your Jaguar was missfirieing did it make like thuds or popping sounds on idle?? thanks Pierce.

 

Mine did, and missed like hell, before I got the codes and changed my plugs and coils