boxster mot failure! emissions. help

alexmason · 07-05-2008, 12:55 PM

my car won't pass its emissions test on the mot, the co levels are very high 3.97% at fast idle and lambda to low at 0.81, i have replaced the 2 pre cat lambda sensors (there aren't any post cat sensors fitted ?????) and i have also put 2 new catalytic converters on, but this has not changed anything. other than the emissions the car runs very well, the idle is excellent and it pulls very well in fact i have to say that it drives great, and there are no engine managment lights on. i have checked around the engine and all the pipes and plug seem to be in good condition and attached,

i am now running out of faith and don't know what to do next. any advice would be most welcome

my car is a 1999 t reg boxster 2.5, the car is a 1 owner fsh and 51,000 on the clock, the only odd thing is that the car was bought from germany built july 1999 but was not register in britain until october 2000, on the build spec sheet it has the option code c26 south african equipment and v26 south africa equipment rhd, does anyone know what this would change on the car and could this effect the cars emissions.
yours very confussed alex

Britwrench · 07-05-2008, 06:24 PM

Put the car on a PST2, PIWIS or Autologic tester and see what is actually happening.
Replacing parts without running the test will only cost more money and not achieve anything.

alexmason · 07-06-2008, 11:45 AM

at the moment i don't have a tester, i am considering buying one but not quite sure what one to buy as i work on many different types of cars not just porsche's, i want one with the best info but a good coverage of vehicles.

had another look at the engine today, cleaned the MAF, disconnected the battery for an hour and checked all the pipes. found that the jubilee clip that holds the main air pipe from air filter to thottle body had snapped, so changed this and put some redex in the tank.

used a friends gunson gastester, calibrated the CO reading to 2% for normal air as instructed, put the probe in the exhaust stream and the reading showed -0.65 at idle. although this seemed a crued test i'm hoping that the problem is solved, going back to M.O.T station for a retest tomorrow, fingers crossed.