MOT hydrocarbon & lambda FAIL

[Jwelsh03]

Hello all,

Tok my 1993 Chimaera 4.0 for an MOT about a month ago and it failed on excessive exhaust hydrocarbons and high lambda reading. At the time there was a carbon smell and come smoke under hard acceleration.
I have then replaced all the plugs & leads, stepper motor and MAF sensor.
I have had another test today and has failed again on the same issues.
The car is running very smoothly with little to no smoke.
Any ideas on how to reduce the hydrocarbon and lambda readings?
Thanks

[Belle427]

Can you post up the readings?
High lambda would suggest lean running maybe due to an exhaust leak but thats just a guess.
Changing too many parts at once can sometimes hinder fault finding.

[blaze_away]

Is it running "full vacuum" advance ?

If yes it needs to be put back to "ported" vacuum advance for MoT's