Ah! On the other hand we have what is essentially the Plus 4 SS system plus the second sonda lambda sensor which checks the functioning of the cat (in compliance with homologation regs.). Unfortunately in our case there are times when the cat does not get hot enough to function, or cools down, and after a certain period programed into the ECU the light comes on.

Gas analysis tests indicate the functioning of the cat is marginal and this is in part due to the longer exhaust manifold but I am reliably informed that it can also be contributed to by tiny variations between one engine and another.

One thing that we may try is a faster upstream sensor which may help a little by adjusting the fuel mix a little sooner.

Peter

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