Explain this if you can

[glynnd]

I have had an ongoing intermittent problem with my car regarding the car not performing properly. I had changed the maf put forte through the fuel system had it serviced even though it was not ready checked everything with vag com and found no codes but still the car performance is good then bad for a day then good again then bad and so on.
I have had the auxillary belt changed and guess what?
The car now performs better than ever and even the aircon is cooler
Somebody tell me what has happened
Glynn

 

[muddyboots]

Have you given it a chance for a bad day again yet ?!

Otherwise I can't see any way it's connected - except that while changing the aux belt, maybe something else got disturbed

 

[sssstew]

yer agreed with Lee

 

[glynnd]

Today its gone funny again and I cant flippin believe it

 

[volkscraft]

Ive seen a misshaped aux belt cause all sorts of probs on a petrol 1.4, but that was to do with cyl recognition. Cant imagine it on a diesel but believe me anything is possible on a modern car.

 

[andycupra]

think we need to know what the car is actually doing.
you say its not performing properly, in what way? just slow?

 

[glynnd]

Not really slow just doesnt pull like it does when its fine. Had a corolla t sport before the leon and I can honestly say that when the leon is running well its not that much slower to 60 than the corolla was. I just feel as though the boost is down when its not running right

 

[sssstew]

if you feel the boost is down do some logging with vag com to compare requested vs actual, put the results into a spreadsheet and compare.

 

[glynnd]

Been there done that
every time I go to do it the bloody thing runs fine again