Mazda 626 Noise + fuel economy - hunters
I have a Mazda 626 GXi SE 2.0i estate. It is nearly 3 years old and has developed a loud in-car resonance (low frequency thrum) at an engine speed of 1500 rpm, both on the move and when stopped. It is particularly bad when cold. Also it appears to have a problem on starting from cold deciding whether to go to the cold start speed (1500 rpm) it goes up and down like a yo-yo for a few seconds then goes to 1500 rpm. I am also only getting a very disappointing 26 mpg on average, instead of the quoted 35. It has been to Mazda twice and they claim not to know what's causing all this. The centre and back box were changed in desperation, but made no difference. Independent garages have suggested the lambda sensors and noisy catalytic converter, although Mazda say not - any body got any ideas?
Mazda 626 Noise + fuel economy - madf
Changing a lambda sensor should be cheap and easy.


A faulty catalyst is not. Have you driven through floods or hit underside on something before noise started? If so, cat could be partially collapsed inside..

Change your Mazda garage : they sound incompetent.


madf