406oc.co.uk

Hello! I have 406 2.0HDI 110 from 1999. The problem with bad acceleration in low rpm is confusing me . I think the problem is with the turbocharer since sometimes it doesn't turn on on time, for example when I'm on 3rd gear the turbo starts after 3000rpm . I bought the car recently and before i bought it I drove my friend's 406 with the same engine and compared to mine it's flying .
I have only changed the air filter .
P.S The exhaust is broken through ,can this influence the car's performance too?

Hi there,

I would start at the air flow meter. These can give problems and lead the car to act like yours.
Unplug the air flow meter and take it for a drive, if this cures the issue you will simply need a new one.
Try to get an OEM as aftermarket cheap meters can just be as bad.

Hope this helps!!

Agreed - the air flow sensor ( sometimes referred to as a MAF sensor ) gets dirty over time and gives duff information - unplugging it makes the ECU resort to a default setting....
If your car improves then as already suggested, try to find a genuine one ( Siemens VDO) from a local motor factors - check online for discount codes.

If there is no improvement then I would next consider a vacuum leak or a boost leak.
Check the bottom of the intercooler for bubbles when you rev the engine - it's normally a bit oily down there so easy to see bubbles - and the big pipe from the top of the intercooler should expand and go hard when revved

If this looks okay then next check the small black pipes that come from the 2 solenoids on the driver's side of the bulkhead. Follow these with your fingers checking for splits and damaged ends.
Basically a vacuum leak will starve the turbo momentarily until it gets enough revs/vacuum to close the wastegate and allow boost..!!

Good luck with it, please let us know how you get on.

Have your brakes deteriorated at all? The vacuum pump can fail and provide to little to control the turbo properly.

Peter