Derek GA

Hi, has any any experience with the F20c producing really high hydrocarbons, mines a 2003 with 112,000 miles recently serviced new oil filter air filter lamda and 02 sensors are not shown any faults or bad readings cat is new, the car has got very heavy on fuel too and when tested the HCs are 45% above tolerances on the emmissions tests,
im in Ireland and any mechanics I ask are not interested in getting under the bonnet to investigate, soon as I mention it’s an S2000 their fobbing me off, any help would be appreciated thanks

noodels

What sort of cat are you using ?
did you put spark plugs in with the service ?if so type used.
is exhaust leaking ?
valve clearance done ?
if all done ,do a leakdown test for valve issues

Car Analogy

Maybe an engine temp sensor? When engine is cold, ecu will supply an overrich mixture. Similar concept to what the choke did on an old school carbureted engine. When dead cold, engine needs rich mixture.

But as it starts to warm up, ecu pulls mixture back towards stoichiometric. But if ecu never realizes engine has warmed up, it could keep supplying this overrich mixture, which would result in excess hydrocarbons in exhaust.

Is the coolant temp gauge behaving normally? I believe ecu gets its engine temp reading from same place gauge does.

flanders

Can you show us all the readings from the emissions test.