Disco 3.9 V8i 1996

I have a misfire. It is worse when cold or under load. It lacks power when going uphill and will not rev past about 4000rpm. Have done all the usual things after searching the forum, plugs, leads, distributor cap, air flow meter etc. However when revving it at a steady 3000 / 4000 revs (to see if it would clear) it sounded like one of the cats was disintegrating. It was also glowing red hot. The question is : could a cat cause the misfire?
Any help would be appreciated.

If you had a fire in the cat, that wouldn't help

There shouldn't be sufficient fuel available to burn at that point, so you have an afterburner attachment (that we all want one of) there's a fuel problem or it's just clagged up and need a good run.

Ours need a good blow out once a week after toodling round locally.

Peter

Very possible that the matrix in the cat that was glowing has melted,broken up and is now blocking the exhaust further downstream.This will cause lack of power and missfiring as the engine cant breathe properly.Try undoing the exhaust at the back of the Y branch before the centre silencer,jack it apart at the joint and drive it.It will be a bit loud,but if it restores performance the silencer will be full of bits.......

tfoss said:

I have a misfire. It is worse when cold or under load. It lacks power when going uphill and will not rev past about 4000rpm. Have done all the usual things after searching the forum, plugs, leads, distributor cap, air flow meter etc. However when revving it at a steady 3000 / 4000 revs (to see if it would clear) it sounded like one of the cats was disintegrating. It was also glowing red hot. The question is : could a cat cause the misfire?
Any help would be appreciated.

Click to expand...

hi had a vauxhall once with a miss fire and the cat glowing red hot.it was the h/ t leads and the top chian part on one of the plugs had a hair line crack down it good luck.

I had a Cavalier that the matrix in the cat had broken up in. That caused the same symptoms as you are describing. It was a company car and after going in and out of the garage doing things like plugs etc etc, one of the mechanics put his hand over the tailpipe and found tiny pieces of gold which is how they diagnosed it. New cat fitted and it was like new.