The MGF Register Forums

MGTF 135 year 2003 64k miles
I took the car for its french MOT today, passed except Co2 reading was 0.7 when its a 0.3 max.
Inspector thinks it might have an ex leak before the lamba sensor?

history is that last week we put a new head gasket with timimg belt and water pump.
Used a good head from a 1997 120 bhp car had it skimmed , and used the cams etc from the 135.

Apart from that no issues.

Where to start with looking for and solving this?

I would start by looking for air leaks.

talkingcars wrote:I would start by looking for air leaks.

Inlet or exhaust side?

I was told that HC being high would be the result of leaks and not the CO2 readings.

An exhaust leak before the first lambda probe can cause a misrepresentation of the exhaust gases which causes the ECU to adjust fuelling.

Just found that when we finished the head gasket repair, forgot to connect the air box to the throttle body
Lots of air going in and maybe a high Co2 reading?

Cannot see that making much difference. On Blue it was a faulty CAT................ a faulty new CAT at that.

My VVC failed its emissions test once due to a leaking gasket betwixt the exhaust manifold and downpipe, and a very small leak at that.

Plezier wrote:Cannot see that making much difference. On Blue it was a faulty CAT................ a faulty new CAT at that.

Ditto. Replaced mine with a Bose cat and all good.

First thing will be put it on the ramp we have here, and look for exhaust leaks.
then see where we go.

Good luck as I know full well just how frustrating tryign to solve this can be.