3 replies to this topic

[Racing Gold]

Thought this story may help when sorting emissions on Spi's and in particular 1992 twin plug ECU ones which seem to suffer more than most. I received a call from a bloke who said his wife's Spi went in for MOT in Sptember 2008 and it failed on a few things, including emissions. The garage did the mechanical bits, steering rack boot brake lights that sort of thing but did not/could not cure the emissions. They had an auto electrician look at it with same result. They had done the usual thing like change the Lamba but CO was 12 and hydrocarbons 1206!!. In Decenber they asked him to collect it, gave him a bill for £300 and NO Mot. I got the call not because I am a garage but because my son and I race in Mighty Minis. and a bloke he worked with had heard of us. I put my code reader on it and the readings were all OK but the lambda was reading 2.1v- far too rich, a favourite on these early cars. I started by taking off the inlet and exhaust manifold and rechecking what the garage had done. First thing was a reused downpipe gasket which had been leaking where the lambdascrews in so I changed this. One of the pipes at the back of the injector housing was split and it had been 'repaired' with a cable tie- I replaced this. Being a 92- it had that elbow coming off the injector to the breather rail which is plastic part way and holds the metal filter discs. I binned this and fitted the single pipe as fitted to the later Spi's without the metalfilter discs. Having doen this, the Lambda reading dropped to 1.9v-still too rich. I contacted the owner and got a bit of history of the car. Turned out his wife only got it in July 2008 and they found it was running lumpy and faltered when idling so I surmised the problem was long standing and fuel damage to the cat etc could well be the problem. I took the cheap route for him first by changing the purge valve,(we take them off the race Mins so loads spare), and the charcoal cannister. The lambda dropped to 0.9 and once warm, did then vary and the car ran better. I took it to my friendly MOT station to test the Hydro Carbons and they had fallen from 1206 to 267- still a failure, (200 limit on Spi) and co was still high at 6, but again lowered. That only left the cat as being responsible for that final bit and once changed, hydrocarbons fell to 69 and Co was well within limits .

I am not saying this will cure all with these problems- but something to think about

[DaveRob]

For all those with problems with idle and rich running..... its worth noting the logical approach here. Check for leaks, check the vacuum tube and remember that if its been running rich for a while the cat may be kippered......... then after you have it all sorted......... maintanance all the time. Good informative post thanks

Rob

[SMP]

Is it true that a new cat can hide a an underlying problem - so the emissions come down but in a years time the new cat is wrecked by the problem and the emissions have gone up again?

Steve

[minidaves]

sounds like a air leak to me

dave