Hi

I've another thread on the go in IVA/Legal but think this is more of an engine question.

My 1992 Mazda MX5 donor which should be tested to 3.5 CO/1200ppm HC has a catalyst.

Do you think it needs the cat to get to these levels or is it Mazda overkill ?

What are my chances of getting through emissions without a cat on my kit ?

thanks
Paul

Ive made a few de-cat pipes including one for a MX5 (not sure of age) in which i beleive none have passed a legitimate MOT with out issues therfore i would imagine that the catalytic convertor would be a good idea

doh !! That's what I was afraid of. Could have gone for a later engine then !!

Presumably my ECU can read back from the cat though as it has probes cabled in.

What I don't yet understand is if you have a given engine under engine management, can you just add a cat and drop you're emissions without doing anything else ? Or do you have to add lambda sensor as well ?

Think I need to do a bit more reading around - anyone seen any good websites on this ?

thanks

you'll breeze through the iva without a cat, i've had a hand in a few iva'd mx5's and all of them had co around 0.4 prior to the cats fitting (Low volume manufacturer, so they have to meet the current emmisions)
and ppm well under 100

Leave the cat out it's not required.

Hi Paul fitting a cat to any petrol engine will reduce carbon monoxide thats the job of the cat basically to convert carbon Dioxide into carbon monoxide, irrespective of a lambda controller. The lambda sensor just monitors and trims fuel and ingnition back for optimum efficiency and low emissions

whoops i ment converts carbon monoxide into carbon dioxide!

Thanks for further info.

Chris - the Mx5 you've IVA'd, were they Mark 1s ? Mine's a 1992 1.6...

Paul, there was .................

1 1991 1600cc
1 1992 1600cc
1 1995 1800cc

all were pretty much the same pre cat, for the ameteur builder a cat wouldn't be required for an pre 1995 mx5.

Nice one - thanks Chris.