Probably been asked 100times but...

Does anyone know what CO reading you get from a UK scoob without any CATs, and is it below the maximum MOT limit?

I'm writing this as I just ordered a flowed downpipe, and I've already done the duty of kicking out the second cat

currently it still does 0% CO

My old '92 XR3i (1.8 130bhp Zetec) Had its cat removed after it decided to shatter and block up my exhaust! And it would pass the MOT! (yes it did have the stricter cat emission test).

It did need a fuel system clean and new spark plugs to get it to pass the 3rd time though!

Surely If a crappy dagenham dusbin with an old yankee cast iron CVH block and a fancy 16valve head plonked on top can do it, a scoob should!!

 

I don't know the figures but any Scoob will not pass the MOT with no Cat's.....

Matt

 

Legally it shouldn't. That doesnt mean all do fail, im sure many pass. After Aug 92 all cars are supposed to have a functioning cat. A properly running efi lambda controlled car should read 0.1%CO with the CAT removed. Zero with cat.
Different MOT stations may look upon it differently. Even here in NI were MOT testing stations are government run, most cars with cats removed pass provided they are below the 3.5%CO level for most cars. Times are changin though, with full testing on suspension ( shocks/bushes ? more?, lights and god knows what else at these new stations. The first station to open had a 95% fail rate!!!!!!!!!! in the first month. I think you all have it lucky in england!

 

Hmmm,

Dodgy area, Escort used to do 3.2%CO (on a good day) which was just under the limit. Suppose in the end of the day its down to how well my scoobs running at the time of MOT.

Pity no-one makes a high-flow CAT thats a reasonable price

 

The MOT emission test for a 'cat car takes readings at 2 engines speeds - normal idle (say 750 rpm) and fast idle (say 2500 rpm). Pass limits for CO might be say .3% and a decent 'cat will take out all the CO. The test for older cars was only taken at idle and usually 3.5% is the CO limit. A reasonably tuned non-'cat engine should run at say 1 - 2% CO at idle but if it was over the 3.5% limit could probably be tweaked to pass the test. However to tune it to run reasonably and pass the stricter 'cat limit (without a 'cat) at idle would not usually be possible. Passing the CO fast idle limit is easier as CO emissions drop considerably as revs increase. There are also HC emissions to consider although that is less of a problem and a reasonably tuned engine without a 'cat should usually squeeze under the 200 ppm 'cat test limit. Best bet is to find a "friendly" garage. All this IMHO only. DL

[Edited by David Lock - 5/10/2002 9:55:23 AM]