Emissions - Yep, back to that old perennial again.

Trying to get Hari's 1996 MGF VVC back on the road after lying idle for months after I fitted a new clutch but it keeps failing the MOT on emissions. For its last MOT back in April 2013 I fitted a new cat and a used lambda sensor, the car has done around 5000 miles since then.



Limits:-

CO 0.2%

HC 200ppm

Lambda 0.97-1.03



Feb. 6. Emissions:-

FAST IDLE

CO 2.54

HC 228

Lambda 0.94



I had an expensive diagnostic check carried out with the inconclusive result:-

"Checked engine ECT signal and found to be working ok.

Upstream Hego switching slowly, suspect Hego fault."

I was advised to replace the O2 sensor which should do the trick.



Put in a new O2 sensor, cleaned out the exhaust ports etc. and -



Dec. 18. Emissions:-

FAST IDLE

CO 2.15

HC 144

Lambda 1.1

2ND FAST IDLE

CO 4.29

HC 191

Lambda 0.88

IDLE

CO 1.71



I have taken off the manifold, cleaned the meeting faces and replaced the gasket, fitted new coil packs, plugs and leads and will be fitting a new water temp. sensor before the next test on Monday morning.



Why on earth do things seem to be getting worse?

What should I look at if it fails again?

What sort of cream cheese is the moon made of?



I am pretty good at swinging a hammer around, but these electronic spanners in the works are a bit baffling particularly when diagnostic tests don't diagnose whilst being ridiculously expensive.



Happy New Year to you All.



Mike

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