Hi there i have a 2001 mk3 mondeo 1.8 duratec petrol.just gone in for mot and hc abit high infact a fail.now ive tried redex and engine flushes but still high,but how ever when i took off the air pipe from the airbox to throttle body it passes emissions no probthis car hasnt a maf fitted either has had new airfilter fuel filter has any1 any ideas regards pete

[quote name='ppeter7' timestamp='1358889142' post='229370']
Hi there i have a 2001 mk3 mondeo 1.8 duratec petrol.just gone in for mot and hc abit high infact a fail.now ive tried redex and engine flushes but still high,but how ever when i took off the air pipe from the airbox to throttle body it passes emissions no probthis car hasnt a maf fitted either has had new airfilter fuel filter has any1 any ideas regards pete
[/quote]

high hc emissions is caused by a rich fuel mixture. could be due to worn spark plugs not burning the fuel properly or a lambda sensor. removing the air intake pipe is kinda proving this as you are now allowing a completely unrestricted airflow which is probably balancing the mixture

ok must be lambda as i had plugs done to at same time and all parts fitted was gen ford parts thanks again stef123

[quote name='ppeter7' timestamp='1358915287' post='229465']
ok must be lambda as i had plugs done to at same time and all parts fitted was gen ford parts thanks again stef123
[/quote]

The lambda sensors can be checked with a live data scanner. The front lambda sensor is the one you need to look at, it should be switching fairly quickly.