Lack of boost low in rev range.

[Demon6j]

Hi my 2013 ibiza cupra suffering from lack of boost low in the rev range intermittently and it does not throw the engine management light on. Also what can only be described as a metal sound like something is rolling inside the exhaust under acceleration and braking has anyone had any of these issues before? Car has done 72,000 miles.

 

[vtxracer]

Possible fault is the water pump. It houses the magnetic clutch for the compressor. If it has failed the compressor will not engage and usually it will sound like you described.

 

[Demon6j]

Possible fault is the water pump. It houses the magnetic clutch for the compressor. If it has failed the compressor will not engage and usually it will sound like you described.

If the magnetic clutch is not engaging would it not throw a code? Have ordered a obd2 adaptor to see if it's showing any boost pressure low down

 

[vtxracer]

Not necessarily. Mine failed. It sounded like a broken timing chain and only got worse as i continued driving. Clutch would not engage but no warnings at all.
I replaced it with whatever brand water pump i could find faster cause i needed the car. The new water pump turned out to be faulty. The clutch would not engage properly resulting in no power. Again no warning lights or codes in the ecu.
Finally replaced it with a brand new vw water pump and works fine since then.

Another possible cause of power loss on low rev could be the flap controlling the compressor/turbo air flow. The motor fails, the flap is stuck.
99% of the time, it will throw an ecu code. But i cant explain the sound you can hear in this case.

 

[Demon6j]

Not necessarily. Mine failed. It sounded like a broken timing chain and only got worse as i continued driving. Clutch would not engage but no warnings at all.
I replaced it with whatever brand water pump i could find faster cause i needed the car. The new water pump turned out to be faulty. The clutch would not engage properly resulting in no power. Again no warning lights or codes in the ecu.
Finally replaced it with a brand new vw water pump and works fine since then.

Another possible cause of power loss on low rev could be the flap controlling the compressor/turbo air flow. The motor fails, the flap is stuck.
99% of the time, it will throw an ecu code. But i cant explain the sound you can hear in this case.

Thanks for that much appreciated