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MOT & Emissions Question

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951 views 9 replies 7 participants last post by  oskiee6 
#1 ·
Hello all,

Had my MOT yesterday and it passed on everything and only just managed to pass on emissions..(same old weak spot on these cars).

Now, i put a new NTK lambda on the day before the MOT and filled up with Optimax.
Fuel system was cleaned out using Slick50 last month. No issues or problems apart from the bouncing revs @ 2k where engine judders when holding @ 2k. CAT is also fine and car drives fine overall and fuel consumption is average.

The examiner said its down to the larger exhaust I have on the car (2 box Ragazzon from cat back) as it is a larger bore and will affect the mixture and emissions overall.

QUESTION: Is there anything I can do the correct the mixture and keep the emissions down? When its idleing there is a stronger than normal smell of petrol fumes.

Oh, Its had a new BOSCH maf, air filter, plugs, temp/sender & stat + all the BBOB has been prof rewired - no errors.

Car is a 2000 145 QV - All standard apart from exhaust.

Any help appreciated.

Thanks
 
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#3 ·
Yeah i'd go for cat as well, sometimes you can tell when a cat is dead. It will smell like rotten eggs, or if the monolith has callapsed it will stop the engine revving out tidy, sometimes severly. I knew mine was on its way out because every time I drove it hard it stunk, failed the MOT for it.
 
#5 ·
Thanks for the responses all.

The CAT doesnt smell or anything and I agree with the comment about the larger bore exhaust as the diagnostics have shown the lambda up with intermittent faults/switching even though it was new. The actual exhaust itself isnt too much bigger than a standard set-up. Its just the 2 rear silencers and a stainless pipe section to the CAT.

The CAT doesn't rattle or anything but I will be investigating further as sometimes it does seem really hesitant and the revs just randomly flicker either way. Luckily I do have a new cat on hand. Will let you know how it goes.
 
#6 ·
I have had probs in the past using aftermarket lambda sensors, my advice would be to use exclusively the bosch ones originally fitted to the car. I dont have a general bother with aftermarket bits, but on Lambda sensors and MAF's its a bit of a lottery
 
#7 ·
fatdarryl where in cornwall are you as me and a few other alfa owners are on about doing a meet in cornwall. so far my 145, my bro's 156 v6, a mates 147 and the local butchers gt are going. are you going to run to the sun at all as me and me bro are going to bring some style to the event this year with our two alfa's
 
#9 ·
I'm not saying that all aftermarket sensors are dodgy, more that sometimes they arent manufactured to the same tolerances and the ECU may not 'like' the signal from it.


addamski, I'm in Truro, but don't usually get the chance for meets, as I usually work through the weekend... and you couldnt pay me to go to newquay over rtts!! haha
 
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