UK MOT Emissions Failure

[Zino986]

Hi, Thanks for your comments BYprodriver and thstone.

I am wondering if the system is on the change point of EOBD II and as there isn't a post-cat o2 sensor it won't put the CEL on as it doesn't know that there is a problem.

I agree, too much un-burnt fuel coming out of the exhaust, but is this manually adjustable?

What I really need is the figure for the UK MOT test results on a 98' MY 2.5 but I don't know where to find them.

[thstone]

Originally Posted by Zino986

I am wondering if the system is on the change point of EOBD II and as there isn't a post-cat o2 sensor it won't put the CEL on as it doesn't know that there is a problem.

I agree, too much un-burnt fuel coming out of the exhaust, but is this manually adjustable?

The O2 sensor should know that there's a problem when the mix is so rich that you're 7 times over the emissions limit. Strange.

The air/fuel mixture is not manually adjustable. It is determined by the ECU based on inputs from the various engine sensors (MAF, air temp, throttle position, etc). The ECU will enrich the mix under certain circumstances.

If you have a Durametric, get a reading of the fuel trims, maybe that will tell us something.

[Zino986]

Thanks All.

Yes agree, the light should come on at 7 times the limit!
I have access to snapon diagnostics and although I can't go in to the specific vehicle with that, I can look through EOBD. I'll let you know what I find.

In the meantime I have asked the question on Boxa.net, thanks for the pointer.