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the fto and the mot ..

Please note that this is not intended to be a detailed analysis of the MOT test, but more a list of potential problems areas specific to the FTO, and what you can do to minimise the inconvenience and expense of your car failing the annual test.The following information is based on over 30 years in the motor trade and 10 years experience with FTOs. This advice should help you make a more informed decision regarding parts purchase and may also be useful for any DIY'ers out there. 

Exhaust Emissions
This is probably the one area of the MOT test that generates the most  phone calls to us for parts and technical advice.

Testing procedure
Please note that this is our own interpretation of current VOSA MOT regulations with regard to emissions testing and should not be considered as gospel.  The only relevant interpretation is that of the tester examining your vehicle, so it would make sense to validate any of the following information with your local testing station before making any decisions or purchasing parts.

Using a gas analyser whilst the engine is running, the current MOT emissions test measures the CO (carbon monoxide),  HC (hydrocarbon) and the O2 (oxygen) content of the exhaust gas. The O2 test is more commonly known as the lambda test. It is so called because a lambda value of 1 is the name given to the ideal air/fuel ratio, also known as the stoichiometric ratio, of 14.7 to 1 

With regard to the FTO however,  there are potentially two levels of MOT emissions test, with differing requirements, depending upon the date of first registration. That is to say, the date of first registration in Japan and not the UK.

Date of first registration before 31/07/1995. Theoretically a vehicle of this age should be subject to what is known as a ‘non-cat’ test where the maximum CO level is 3.5% and maximum HC level is 1200ppm (parts per million). There is no O2 test requirement, as this test pre-supposes that the vehicle is not equipped with a catalytic converter or the accompanying lambda sensor. This test is carried out at ‘natural idle’ only.

Date of first registration  01/08/1995 to 31/08/2002. A vehicle of this age will be subjected to a ‘cat test’ with maxima of CO 0.3% and HC 200ppm, plus a lambda value of 0.97 to 1.03. This test is carried out both at ‘fast idle ‘ 2500 to 3000 rpm, and natural idle, normally considered to be between 450 and 1500 rpm. Realistically both 4 and 6 cylinder versions of the FTO should idle at around 800rpm when up to normal temperature.

Areas of MOT failure
All  FTOs,  4 cylinder or V6 are equipped with a cat (catalytic converter) as original equipment and any model,  if it is in good condition, would fly through the earlier test and should be able to pass the later, more stringent emissions test quite comfortably.  An FTO failing the earlier ‘non-cat’ test would indicate some pretty serious engine maladies and it would almost certainly be running like a bag of hammers and/or consuming prodigious amounts of fuel. Failure of the later test however is not uncommon, but before we get into the technicalities let’s go back to basics. 

An infrequently or badly serviced FTO will definitely be more likely to fail than it’s properly serviced counterpart. Do yourself a favour and get the car serviced before the MOT. Even without considering expensive component failure such as O2 sensors and cats, your humble ropey spark plugs, minging air filters and even ancient engine oil will all reduce the chances of passing first time.

It is far too complex a subject to go into all of the combinations that could lead to emissions test failure,  but to summarise from experience, the problems are likely to be excessive CO and/or HC readings ie an excessively rich mixture. This can be as a result of poor servicing mentioned above or component failure, but areas to investigate would be lambda sensor, exhaust system and even engine coolant temperature sensor.  Ropey signals from sensors to the engine ECU can play havoc with the mixture and the resultant emission readings. Incidentally,  don’t assume that a lambda fail on the MOT test is automatically a sensor fault. Exhaust leaks, both upstream and downstream from the sensor, can materially affect O2 readings that could lead to an unacceptable lambda value from an otherwise good sensor.

Similarly do not assume that high CO levels always mean a faulty catalytic converter. A popular, if not particularly eco-friendly, modification by some FTO owners in search of increased power  is to remove the standard catalytic converter.  We have seen emission readings as low as 0.60% CO from a de-catted but otherwise healthy FTO GPX;  so you can see that, even in this state, the car would pass the earlier test quite comfortably and wouldn’t be a million miles away from the later test. Following this vein of logic, CO readings of 2 or 3 % almost certainly indicates an additional underlying problem with or without a paggered cat.

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IMPORTANT
Although we have been very careful in the compilation of the advice pages of our website and the content is thoroughly checked by our panel of specialists,  we cannot be held responsible for any loss or damage caused if you decide to follow the advice contained herein. 

Please bear in mind that a job which may well be a piece of p*ss on a vehicle lift, could easily turn into a total nightmare when lying on your back in the regulation puddle. Don't tackle any work unless you are confident that you fully understand the complexity of the job you are undertaking. Make sure that you have the correct tools, always wear the appropriate protection and never, ever work under an unsupported vehicle. If you are not confident that you can complete the job, then it should be entrusted to a specialist.

If you feel that there are any errors on any aspect of this page, or you simply wish to comment, please call Malcolm on 0191 586 7724

or you can email us here


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