December 8, 2013, 8:56 pm
very few garages have a back pressure tester...i had to get one from the states myself as they are a very useful tool
access ports are blanking plugs in the exhaust system, not many cars have them but if you have they are used for the purpose of tools such as pressure testers...normally find them in the manifolds or downpipes...tbh, dont think ive ever seen the on euro fords but not worked on a v6 mondeo so maybe they have.
yes, the front lambda, important the electrics are still connected during test so strap it out of harms way whilst giving it a spin.
this will only test for blockage in exhaust, not just the cats either, but if there is a noticable improvement then you can then work to finding exactly where the blockage is.
lambda sensors can be tested with a voltmeter..can give a rundown on how, all you will need is a blowtorch and a voltmeter that measures low volts.
can do a rough test of cats by temperature...compare the temp at inlet and outlet of cat, should be roughly the same...ideally measure with a voltmeter with a temp probe...but this is only a rough test.
the fact you had the miss made me suspect a possible blockage...but its just as plausible that back box for eg has collapsed in on itself...not uncommon and totally unrelated to misfire