Lack of engine power - possible causes?

Air filter, blocked exhaust (broken cat is very common), cam timing slipped a tooth. These would be the first things to check.

Very Unlikely.

Unlikely, & you'd normally get a fault code

Possibly , but you'd get a fault code

Cold start sensor/ Air temp sensor

You can play hunt with some wd40 easily

Cam belt's jumped, or exhaust/cat blocked as Mr Cheerful says, an air leak that only opens when the engine moves on its mounts.

If it has EGR it might be worth checking the valve or even taking it off and cleaning it. Or, depending how it operates, disable it temporarily to see if it's anything to do with the problem.

usually egr fault is low speed problem, flat out there is no real difference.

years ago a friend had a Cortina that he used as a taxi, it burnt oil through the stem seals, eventually it built up so much crud on the back of the valves that power was well down, one day a valve's worth fell off, holding the valve open, that was when it got taken to bits and everything became clear.

CVH engines suffer from seal problems, so perhaps that is what is happening here?

Original Poster here. Thanks to all for replying with your ideas. There's one other bit of info I should have posted earlier. A couple of days before my daughter reported the problem, I had changed the exhaust system seal (ring joint) which was just upstream of the Cat. It was blowing noisily and when I opened the joint, the seal was clearly breaking up quite badly. I pulled out the joint, which had some missing bits, and replaced with a new sealing ring. I had assumed that any fragments from the seal would have blown out of the system. But now I'm starting to wonder if something had got to the Cat.

Anyway, I need to look more closely at the Cat. How do check it out without special tools? I assume I could check the pressure before the Cat, or the pressure drop across it? And would I need to measure the temperature upstream and downstream of the Cat?

Can I clean a cat, once I've got it out of the car? How?

I see I can get a replacement cat for around £50. Is that likely to be the best solution if I have any doubts about the condition of the existing Cat?

Steve

The blow eould have been letting enough gases through, fixing it has made everything go through the rest of the exhaust, if it is blocked then it can't run right. There is a way of testing with back pressure in the pipe. Taking the cat off and blowing through it 'may' confirm it, rattling bits is definite. 50 quid is cheap. If you dare run and drive it it with the exhaust off then the blocked cat diagnosis is easier !!

Mrcheerful

OK, if you are within 50 miles of Darlington you may hear a couple of test runs on Saturday morning!. I'm near the airport so will try to coincide my tests with take-offs.

Could be that a blocked cat caused the gases to find their own way out and that's what started and enlarged the blow and broken up seal in the first place...

Yup, it seems that's what might have happened. Bits had definitely come loose inside. Changed the Cat (£56 inc VAT, if anyone is interested), and the poor old engine has gor a new lease of life.

THANKS TO EVERYONE for pointing me in the right direction. Aren't newsgroups great?

Best wishes Steve

don't forget to take the old cat in for scrap. 20 -40 pounds worth