MOT - Hydrocarbons

[davidn]

Just had MOT - passed - wahey. Question, the emmissions printout shows the hydrocarbon readings vary from one tail pipe to the other. I thought the exhaust system was linked after the manifolds and before the back box. So why the different readings?
David

[IPAddis]

Likely to be just tolerances of the measuring equipment. It's not a precise art and the equipment isn't exactly treated gently.

[2 sheds]

Also the "Y" piece that splits the exhaust just before the Silencer is slightly offset so that at idle exhaust flow would tend to "favour" one side.
Tim

[davidn]

Thanks chaps, all makes sense to me. Bloke at the test centre wouldn't have it that the pipes were joined. He even drew me a diagram, very pretty.
David

[simpo two]

davidn said:

Bloke at the test centre wouldn't have it that the pipes were joined. He even drew me a diagram, very pretty. David

Incredible. All he had to do was look underneath - something you have to do during an MOT anyway!