MOT C/O level - 11%, desperate help needed!

[rich1]

my 1991 golf gti (pre-cat) failed its mot today on a couple of wipers, rear no. plate light but more worryingly the emissions! the MOT man said it was running at 11% and the normal level for this year should be 3%. I'm very worried that im not gonna be able to sort this problem and i can imagine the MOT guy trying to rip me off! Im a competent diy mechanic so hope that i can sort this issue out before tomorrow?

any ideas on what i can do? i have checked the air filter and that is pretty clean, the exhaust is leaking slightly, would this cause the problem? is there a way to adjust the c/o level?

any help much apreciated is this time of crisis!

[Horney]

Check the Haynes, but I'm prety sure this is all related to the dreaded MAF senser in the Airbox. I think there is a bit you can turn to alter the reaction of said senser to alter the C/O output.

Only problem is you need a gas analyser to set it up!

Nick

[rich1]

thanks for your reply nick, i was thinking that the c/o can be adjusted - it can? unfortunately i don't have a haynes manual at the moment, is it that the MAF sensor has gone wrong or is it just a case of adjusting the sensor - if so, how?
thanks!

[tinman]

If you have a hole in the exhaust its probably the first thing to repair - the hole is allowing air to be sucked in.

[rich1]

thanks for all your help. does anyone know how to adjust the c/o, is it an adjustment within the airbox?

cheers

[Lewy]

Hole in the exhaust? It would've failed the MOT on that if there was one, plus it would have a lower c/o level if it was sucking in air after the mixture has been burnt.

Try looking for an air leak on the plenum side of the airbox, as this will increase the amount of air being sucked in, therefore increasing the amount of fuel being drawn in and burnt, giving you a high c/o level.

If the MOT station is any good they may adjust it for you for a small fee.

[rich1]

Its all sorted,

still a bit pissed off though, i adjusted the mixture last night and this morning took it to the mot station, the guy doesn't actually do the mot's at his premises, he does them at his mates as he doesnt have the equipment. he wanted to take the car and make me wait at his garage, i insisted that i go with him, we get there and he plugs the sensor in the exhaust, instead of running rich it is now running lean, so i adjust it to get a 2% reading and i do infact adjust it past where it was to start with! i honestly believe the guy was lying as if it was 11% co it wouldve run like a bag of sh!t and it runs perfectly!

also, the car needed the brake fluid changing and a pedal rubber replacing, i did these, he didnt even ask me if they had been done and he didnt even get in the car for the retest,

moral of the story, watch yourselfs people there is some dodgy garages out there! if you have someone you honestly trust stick with them!! a lot of garages are just out there to make money by lying to people, you HAVE to know what your talking about otherwise they will stitch you up!

[wellfan]

Rich 1
Welcome to the sad world of conmen. I would love to meet an honest mechanic or an honest garage. Apologies to all you honest guys out there, however, where are you, I have given up. Where are you?

[monzablue16v]

More importantly where are you sure people on here know of decent dub garages just ask.

[Lewy]

Rich 1
Welcome to the sad world of conmen. I would love to meet an honest mechanic or an honest garage. Apologies to all you honest guys out there, however, where are you, I have given up. Where are you?

You cheeky monkey  I'm an honest mechanic, just ill informed!! And as for the garage, well the Queen owns it, so it should be honest, lol.