Re:Bit of help needed here

UPDATE:

Ok found my OBDII Reader - its an Aldi job but got reasonable reviews and didn't break the bank - Unfortunately this reveals "NO CODES"

So I'm still a bit in the dark as to what to do next

Isn't the stored area called "pending DTC"?
Sorry it's been a long time since I plugged in a code reader. I think my CAT is BM and because a local exhaust place fitted it I can't describe it as cheap, reputable maybe, ebay possibly, as I don't know how they obtained it. :laugh:
Works fine though.
My gut feeling is Lamda based entirely on guess work. Have you anyway to check the emissions at this time, cheap Gunson gas analyser is good enough.

Yeah the "pending" thing - I couldn't find anything there either. I'll give it another try tomorrow.

It's very frustrating.
Apart from the two sensors either side of the CAT and the cam and crank sensors, is there something else that could be the cause of this?

Yes unfortunately.
Anything eldctrical-poor cable / connector etc, faulty injector or fuel pump / pressure regulator, I could keep going. These random faults are the devil's own.

I keep thinking you Lambda sensor is out and here is why:
Sons Toyota MR2 purchased by us with 12 month MOT and in the document pack a receipt for a £1K Toyota CAT just before MOT - ouch!
Next MOT car fails catastrophically with emissions, 5% co, no faults codes, and a few other things!
Car idle a little unstable, but other than this it runs fine, looks like the CAT again.
I push ahead and fit a new Lambda instead and it sorts the car out, idles perfectly and co .5%
So a new CAT can hide a failed Lambda sensor.
This is why I was interested in if you could get emissions tested. High CO with acceptable HC would suggest the same problem.

But it's just one of many possibilities.

It could be worth systematically unplugging and replugging all the engine connectors and sensors in turn to eliminate a bad or failing one. It's a bit of a task but it's also free. If you don't fancy that then you could start with the air flow sensor just after the filter box and follow the path of the air same with fuel and spark. You just have to be logical about it.

Thanks guys - any suggestions is much better than clutching at straws with this! Also helping me find these components too - the pointer to where that air-flow sensor is is very helpful

I chanced a trip over to Evesham in yesterday's heat and a bad hill to go up on the way back total (30 miles) - I was a bit worried but got back with no major rough running.

Today I have to do a much longer run to Shropshire and back (128 miles) - it was on this same route that I almost didnt get back, but that was before the crank/cam sensor change - a bit of trepidation nevertheless.