Emissions / fuelling issues.
I hope this makes sense, bear with me!
Background: 1998 Alfa Spider with the 2.0 (CF2) engine. 150k miles, running well with no other issues. O2/lambda checked and OK, CAT is 13months old and EU approved.
My Spider failed its (Dutch) MOT 2 weeks ago due to high CO emissions. I have had various gas analyser tests done but a typical result is:
At higher revs the CO falls further, although never lower than about 0.45 and HC reduces slightly too. On idle the CO can go as high as 0.8 and HC up to around 180ppm
I have had a smoke test done on the exhaust system and there are no air leaks anywhere in the system.
I have had a heat test done on the CAT and temp drop front to back is only around 15c.
The O2 sensor has been checked and is working.
All the tests I have had done indicate that the CAT isnt working (temp tests etc) - the CAT is easily inside its two year warranty. I have tried claiming for a new CAT from the supplying company and have jumped through all their hoops (costing me about 100quid in garage time) but they still refuse to replace the CAT. Their official stance is that the car is overfuelling - stating a 'healthy' engine should only produce around 20ppm HC at all rev/idle conditions.....
My trusted mechanic who has 20yrs experience with Alfas is pointing the finger at the CAT, the CAT company dont want to know, I dont have mega funds to tackle this at the moment (dont ask what this car has cost me over the years) and my mechanic says he is 99% certain the car isnt overfuelling.
Does anyone with experience in these type of things have any advice to offer?
Are the HC readings suspect, and do they point to an over fuelling issue?
The engine oil is fresh, the spark plugs are around 4yrs/15k miles old, but well within their service life.
What sort of fuel/air mix should I be expecting??
My mechanic is going to 'detergent' the fuel system and then use some Octane booster to try and get it through the MOT, but failing that im not quite sure where to go with this.
Im ****ed off with the CAT company and feel as though I have been given the run-around but cant ignore the possibility that they may be right..... if it makes any difference their CAT is about 1/3 volume of the OE part that came off last year. BTW this is the first time the car has been MOT tested with this CAT in place.
The temp test on the CAT would ordinarily give a result of 65+C temp difference on a healthy CAT - they explained away the 15c dif on mine with excuses.
-1998 916 Spider 2.0TS Lusso-
H&S Corse stage 1.
CATCAMs stage 1 cams with Savali custom ECU remap.
305mm discs with 166 4-pot callipers.
Ragazzon exhaust mid section.
Biscione Racing 2x70mm rear section.
17" Zender Siena wheels with 3mm rear spacers.
etc etc etc!