Cat Damaging Misfire

Hi I have a 2001 3.9 wih the thor engine and I am getting fault codes of cylinders 2 & 6 with a cat damaging misfire I have already replaced all ht leads, plugs, airflow mass meter and coils but still geting the same codes and engine is hesitant when under 2000 rpmand sounds like it is missing a few beats but idles evenly at 750rpm any suggestions

afm maybe?

hi do you mean the air flow meter if so I have just replaced it

I would scope the plug leads and see what the HT waveforms are like before doing anything else.

Leads are the most common for this, as you've done them, change the plugs.

hi I have changed the plugs leads coils and air flow meter any ideas could it be a faulty connector to the coil??

Where did the plug leads come from ? If they are non-gen you may have just masked the fault.Rover v8's dont like cheap ignition components - same goes for the cheap AFM's from E-Bay etc,they are crap.

hi the plug leads came from local land rover dealer in fact on the second set as thought the first set were faulty afm came from local motor factor non genuine would the afm alone cause a misfire in the same 2 cylinders

Can't see how AFM would cause a misfire, especially on just 2 pots. When they go tits up it tends to affect overall engine performance as the fuel ratios get screwed up. Sounds to me like its definately ignition related.

When you changed the plugs, did you make sure they were for the THOR engine. I did some checking and it uses different plugs to the earlier engine, oh and about 5 times the cost per plug!!!!!!!

you aint usin Champion **** plugs are yer? if so, change em fer NGKs.

plugs were supplied by local landy garage so would hope they are right ones

hi just checked rave and the plugs supplied by local landy dealer are for >99my not 99my> would that be enough to do it

Jimbo2212 said:

hi just checked rave and the plugs supplied by local landy dealer are for >99my not 99my> would that be enough to do it

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No.

Jimbo2212 said:

hi just checked rave and the plugs supplied by local landy dealer are for >99my not 99my> would that be enough to do it

Click to expand...

As eightinavee says, they aren't likely to be causing the problem, but running the wrong plugs isn't going to help.

As has been said earlier, these engines are sensitive to the parts fitted, so I would certainly have a word with the supplying dealer and get the right plugs.