Is it true taking the car for a "warm up" will allow the CAT to work more efficiently ? thus lowing the emissions ?? or is this just something I've made up?

 

yes its true.. people say to take it for a good hard spin before you go

 

so it's true people say it .. or its true it makes a difference

 

both ^^

 

 

Id say that it was essential.

 

the mot station will need to have the car at running temps before they test emissions, so the warmer the better

 

Engine temperature and cat temperature arent linear though. Leaving it ticking over will warm the car up nicely, but the engine needs to work a little harder to warm the catalytic converter up...

 

So a blast down the local motorway before hand is in order

 

Ask them to test the emissions whilst its still hot and make it work a little before you get there. Its engine load rather than vehicle speed that you need.

 

It works:

Its not just the cat - the engine has be really toasty. Just letting it warm up on idle doesn't cut it.

It was the only way my decatted Escort would pass - new set of plugs and damn hard thrash. Otherwise it would fail (yes it was tested on the stricter 0.3% CO limit tests).

My old Scoob when decatted so very nearly made it through, but no matter how hard I tried it couldn't quite do it. Once a cat was refitted and giving a thorough "warm up" there was less CO coming out the tailpipe than what was in the air (0.00%).

 

Tip of the day,

Never leave your car at the mot test centre always get the car very warm before you go and and turn up just before time, Reason for this is...

I know a few BAD mot testers if they are having a bad day they will get a car been left out side all day (so cold) so when it goes in on the test station the car is still in cold start mode so extra fueling and high emission that = fail!

As the saying goes, a Warm car is a good car!

 

Get friendly with your MOT examiner. Luckily I live in a small town, one of those places where you seem to know everyone. Have been going to him for 15 years.

I set a time for the MOT with him, take the car for a good drive, around 10 miles, turn up 5 minutes early and hand him the documents so he can do his number checking and computer bit. Whilst he is doing this I take the old girl for a damn good hiding on a local back road, arrive back at the garage where he is waiting with the probe in his hand. So hot you can smell the oil on the engine. Passes first time everytime.

The warm up serves two purposes as he also likes to check the temperature of the discs to make sure the brakes are working evenly. This is because he can only test the brakes using a G meter on the road, as the 2 wheel brake balance tester can damage permanent 4wd transmissions.

He will not pass anything unless it is a genuine pass, and I would not want him to do otherwise. His livelihood and my families safety are at stake.