I have a 58 reg focus tdci 1.9 which is making a deep noise from the air box, someone said check the turbo pipes , done this but all ok, suspected a blocked cat , removed cat and noise still there, any ideas people?

I have a 58 reg focus tdci 1.9 which is making a deep noise from the air box, someone said check the turbo pipes , done this but all ok, suspected a blocked cat , removed cat and noise still there, any ideas people?

Not being silly but have you checked the air filter is installed correctly?

Possibly a damaged or missing seal?

Thanks for ur reply , bt I have checked ul that already, noise is there wen airbox is off. My friend said check the EGR valve, possibly jammed open so am js about to try that, il post wot I find, cheers

Thanks for ur reply , bt I have checked ul that already, noise is there wen airbox is off. My friend said check the EGR valve, possibly jammed open so am js about to try that, il post wot I find, cheers

If your car is fitted with a DPF it could be that that is blocked. Are there any dash lights on?

My brothers 530D started making a deep whistle after his particulate filter was blocked..

also have you checked the integrity of your exhaust system?

Alright Alan , cheers for your reply, I have checked the exhaust system in full, all ok. Have no dash lights ok either but will check the dpf. Noise is more prominent wen air feed pipe is removed from inlet manifold , friend said the block bores may be oval'd and causing back pressure , which the car has slightly, but don't have compression tester to find out, have u came across this before?