Howdy, i got a '79 series 3 XJ.

She's been down on power recently (probably the AFM), and it recently blew out the left rear resonator/glasspack at speed.




I'd just crested a hill under power, when the car dies without warning. Long story short, the resonator had failed, and i ended up blowing out the fibreglass, as you can see above, and limping home.

However it's still down on power, and i figured that either both silencers failed at once, or the catcon had fully died. However testing it today, both sides flow fine, meaning the right hand system did not fail, and the PO had replaced the under floor catcon with the Euro Y pipe.

It runs and drives ok now. But I cannot for the life of me figure out how or why it died at speed if i only blew out the last muffler on one side, leaving the other side unrestricted. And that lack of power still has me concerned that something's still wrong. Not really sure what's going on and all my guesses were wrong. Was hoping someone here might know what the problem is.

 

is it a Series 2 or 3 ? in 1979 they were changing to Series 3.

To me it sounds like ignition, the coil or the ignition module if a Series 3 Fuel injected.

 

Ignition coil or module are both candidates, as Jose says. They often fail when subjected to heat then return to full or partial operation when cooled down.

First, though, I'd pull the fuel filter and empty the contents into a clean jar. What you see (or don't see) will dictate your next stapes

Cheers
DD

 

Series 3.

Fuel and spark was not the issue, that was the first thing i looked at. I took the car out yesterday and it's still a little down on power but running fine.