Mot Passed Today...

February 4, 2005

Right, I know a few people are still unsure if their tubby's will pass an MOT with the CAT replaced with a straight-through downpipe.

Bare in mind mine is a 1994 tubby with boost and fuelling slightly turned up.

I had my MOT today and was assured that on our cars we don't need a cat... but the CO2% still needs to be below 0.30% vol.

If I hadn't known the guys at the MOT place, they wouldn't have tried so hard to get it through the emissions test.

It failed the first and second runs.

Eventually, he got the engine working pretty hard while standing there (not the best thing to do really!) to heat the exhaust system, which helps to lower CO2%.

Once the heat is in the exhaust the tester can run it at the required revs and back off just slightly on the throttle before pressing the button to test. This leans it off a bit.

It took him 10 minutes trying... but got it down to 0.26% vol CO2.

Basically, unless you have an understanding MOT place... your car is unlikely to pass, so be prepared to stick your cat back on for the MOT.

If you have an understanding MOT place, you can get the car through.

They are trying to bring in new machinery to even stop MOT places do this. The machine will pretty much give you 2 tests... and that's the lot. The first test is very straight-forward in that its <0.30 CO2% = PASS, >0.30 CO2% = FAIL. The second test is like a second chance. It's an extended version which enables a little heat to get into the exhaust.

The way to get around this one is warn your MOT friendly place that you're going to bring the car down, and do a safe but spirited drive on the way down... then get them to stick it on the emissions analyser first while it's still really hot.

Hope this clears up a few grey areas with the MOT and catalytic converters on the MR2 turbo.

:thumbsup: