Diesel Smoke Test

Gammy leg · Unread post by **Gammy leg** » 05 Jun 2006, 21:49

Chaps,

Battle bus passed it's MOT on Saturday but I would like a bit of info re: 'Free Acceleration Smoke Test'

I was told when I went to pick it up that it had failed the test first time round and that the tester had to take it for a spin up the bypass and retested it when he got back. results as follows.

Test 1

Test Type - Turbo
Test Limit - 3.00 l/m
Mean of 6 tests = 3.78 l/m
Result - Fail

Test 2

Test Type - Fast Pass
Test limit - 1.50 l/m
Single Test - 0.80 l/m
Result - Pass.

Can anyone enlighten me as to the differences between the 2 tests and why there is more than one acceptable method.

Thanks

Gammy

p20 · Unread post by **p20** » 05 Jun 2006, 22:06

I'm guessing he took it along the bypass giving it plenty of stick. Third gear flat out normally clears the system out. Also known as the 'italian tune up' i believe

Unread post by **Peter.N.** » 05 Jun 2006, 22:31

P20 is right, after a period of relativly gentle driving, soot accumulates in the exhaust system so what comes out of the exhaust on the initial test is soot, not smoke. So next time you take it in for a test give it a good hammering on the way.

jeremy · Unread post by **jeremy** » 05 Jun 2006, 22:52

Why not look it up in the MOT testers handbook

http://www.motuk.co.uk/welcome.htm

Richard Gallagher · Unread post by **Richard Gallagher** » 05 Jun 2006, 23:04

The difference as I understand it is that if the result of the first test/press of the accelerator is below 1.5 then it qualifies as an instant pass.

If the first test has a higher result (more than 1.5) then the result is taken from the average of 6 tests. (IIRC three of which have to be in succession).

bxbodger · Unread post by **bxbodger** » 07 Jun 2006, 14:13

Fast-pass is the reason why you should always give it a good caning on the way to the test. It saves the anguish of watching them repeatedly revving it up to the governor.......