sbloxxy

Hi everyone - hope someone can point me in the right direction:
My car is a 1994 UK 2000 turbo wagon, just bought it and its been heavily messed about with by previous owners. Its running a 3" exhaust with no cat converter (almost certainly hasn't been re-mapped) and it runs fairly roughly to be honest.
Anyway just been in for its MOT and its failed on emissions. It was fine on tickover but failed the second test at higher revs. Apparently it was reading 5-6%, which the tester reckons is due to overfuelling of some sort. He reckons fitting the cat would help but probably not by enough to get it passed - he still maintains that theres another problem thats actually causing the overfuelling. Coolant temp sensor was mentioned.
Anyone got any ideas?

doormatty

how long you had the car
and what did your previous MOT emissions come out at

belliott69

iTrader: (3)

could be lambda sensor, you need at least one cat on there and if it has a dump valve that makes them run richer as well. had the same problem with my 94 wrx and the dump valve made most of the problems. hope that helps mate

sbloxxy

I've only had the car for a couple of months and don't have the readings from the last MOT unfortunately.
But yes it does have a dump valve. Can this be removed for the purposes of the MOT? I know nothing about dump valves - I'm an ok mechanic but have always had BMWs, old Porsches etc.
It sounds as though refitting the cat etc would be the first step.

belliott69

iTrader: (3)

you would need to get a recirc valve to go on there, i got mine of ebay, standard one will do. it would be best to fit the cat first as they make a big difference.

irishscoobysti

iTrader: (1)

i had this problem it was 3.8% then figured out the cat had been taken out by previous smartass..

so fitted a CAT and sailed straight thro, reading was like 0.3%

borrow one off someone for a few days..u only need it for the 20 or so mins their testing it...

sparks_c/s

Hi, pop open the ecu n see if its chiped, had problems in the past with ****e chip upgrades, if so take it out, temp sensors just need resitance checking to see if there in there ohms/temp tolerance, a 10 min job with a multimeter, also add some millers injecta plus get you technician to use trade plates n give it a run, if its been standing for a while this will do wonders, although 6% is a bit high, may also be a good idea to check if it has the correct injectors n air mass meter fitted if you think someones been messing around with it, all this can be done with out fitting the cat, the lambda reading will tell you if you have a problem 0.098 to 1.030 if my memory serves correct. fit the cat when this is sorted, just makes diagnosis easier.

sbloxxy

Just another thought: I know my car needs a set of coilpacks as the ones on it are pretty well knackered and it ocassionally misfires under load. Is this likely to compound the problem? A friend suggested that if its misfiring, it will effectively chuck unburnt fuel into the engine.Any truth in that?

sparks_c/s

If you didnt hear it missing at constant revs then no, not as far as the mot emissions test is concerned.

sbloxxy

Just as a follow up from my original post, I re-fitted the old cat converter and it passed the MOT no problems. Seems to run better too, so I'm debating whether to re-fit the cat bypass pipe (it did sound fantastic) or just leave it alone.