NCT Emmissions Failure

[Mr_MX5]

Hows it Going?
Just had my '94 MX5-Mk1 1.8 V Special, in for its NCT last week and it failed on the exhaust emissions.

Results were:

Temp 82C
Low Idle (850 rpm) CO 0.57 (should be under 0.5)
High Idle (2070 rpm) lambda 0.966 (should be between .97 and 1.03) CO 1.64 (should be under 0.3)

I brought the car to a tuning garage in Dublin and they said the Cat and Lambda sensor are fine. The exhaust was pressure tested and there were no air leaks.

The mechanic tried to put the computer on it but he didn't have the correct software to read my engine type, as its a Jap import. He said that he would have to "fiddle with it for a full day and try to get to the bottom of it by a process of elimination" He wasn't very confident though.

Does anyone know a garage/mechanic (anywhere from Cavan to Dublin) that would have the software for my model or any suggestions on what could be causing the emissions?

The car has an ARC air filter (fitted before i got it) which to be fair isn't clean. I will clean the filter and have the engine hotter (car was only running 25 mins before NCT).

I have read online that cleaning the air filter, changing oil filter, fuel filter and adding a petrol additive should help but my emissions are so far off i'm not sure this will be enough.

Any help or ideas would be brilliant.
Thanks
Gary

[Geese]

I'd almost bet money on the Lamda sensor. See how much one is and replace it.

[MeathMazdaMan]

as matter of interest were the car and lambda sensor tested red hot by your mechanic, if its down on emissions on a hot engine you are probably in bother with one or other, i am in co meath and have two good ones in stock if it helps, ps get that filter back to standard before you retest, i work over lucan way and can recommend a good emissions tester who could do the swaps and retest at his place if you are still in trouble, paul

[Mr_MX5]

Cheers Paul,

The car had been driven for 2 hours before testing the cat and lambda sensor, and pressure testing the exhaust, so it should have been pretty hot at that stage.

I'm gonna clean out the air filter with K&N filter cleaner, change the oil and oil filter, and also the fuel filter, and put a petrol treatment in. The car is back in for a re-test on Monday, so I'll know more then if if fails again.

If it doesn't go thought then, I'll get the details of your guy in Lucan and take it from there.

Cheers again.

Gary.