At the min I've not been having any luck with this car.

I've had issues with the engine light coming on constantly and last time I complained to the garage about it all they did was turn the light off again after having the car a day :(

Now yesterday the light came back on again after being off almost a week so I've sent the car round to one of my customers to read the codes etc.

These are the codes that came up are,

P1137 Additive mixture correction 1 mixture too rich

P1128 Multiplicative mixture correction 1 mixture too lean

P1297 Connection from turbocharger to throttle valve pressure drop

Now the car runs rough at times, especially when cold, very up and down sometimes on tickover, and today I've also noticed if you sit at 2000rpm and go to accelerate not a lot happens except the car feels like its kangaroriing (sp) and spluttering slightly, but if you accelerate at lower revs it seems to be fine.

Any ideas where to start and how to check possible problem areas as its starting to do my nut in lol.

At the min I've not been having any luck with this car.

I've had issues with the engine light coming on constantly and last time I complained to the garage about it all they did was turn the light off again after having the car a day :(

Now yesterday the light came back on again after being off almost a week so I've sent the car round to one of my customers to read the codes etc.

These are the codes that came up are,

P1137 Additive mixture correction 1 mixture too rich

P1128 Multiplicative mixture correction 1 mixture too lean

P1297 Connection from turbocharger to throttle valve pressure drop

Now the car runs rough at times, especially when cold, very up and down sometimes on tickover, and today I've also noticed if you sit at 2000rpm and go to accelerate not a lot happens except the car feels like its kangaroriing (sp) and spluttering slightly, but if you accelerate at lower revs it seems to be fine.

Any ideas where to start and how to check possible problem areas as its starting to do my nut in lol.

Not sure about first ones but the pressure drop is boost change dump valve...I had it on mine bougt a good one and cured it

Also just to add the car is completely standard with no modifications, just took it out and it was fine this time but it comes and goes.

Looked these up on Ross Tech Wiki - The two codes about mixture point to the lambda sensor or the MAF as potential culprit.

The other code is pressure loss between turbo and throttle valve, Ross Tech suggests: Leaking hose, faulty N249, faulty Diverter Valve or throttle body needs cleaning and resetting. Procedure for cleaning and resetting the throttle body has been covered several times on this forum.

Thanks for the info, lambda sensor has been replaced, guess I'll get myself a new MAF.

I can see the P1297 code being a pain after reading a lot of threads lol.

Cleaning the throttle body is always worth doing if you've got jerky throttle response.

Try unplugging the MAF sensor, If the car runs better with the MAF unplugged then you can be 99% sure the MAF is the problem. You can clean the MAF with carb cleaner or Isopropal, which solves the problem if the MAF is gunked up, but if that doesn't work replace it with a genuine VAG part. I bought a MAF from GSF once & it was dreadful !!

Cleaning the throttle body is always worth doing if you've got jerky throttle response.

Try unplugging the MAF sensor, If the car runs better with the MAF unplugged then you can be 99% sure the MAF is the problem. You can clean the MAF with carb cleaner or Isopropal, which solves the problem if the MAF is gunked up, but if that doesn't work replace it with a genuine VAG part. I bought a MAF from GSF once & it was dreadful !!

What make was the one you got from GSF? I'm gonna try unplugging the MAF and see how it runs

I've just unplugged the MAF and run it then tried it again plugged in, felt the same tbh, both ticking over smoothly etc, do I need to take the car on a run with it unplugged at all?

On the fuel trim codes, additive refers to the engine running at idle and multiplicative is when it is running at speed. If it's rich you've got too little air or too much fuel if it's lean too much air or too little fuel.

At idle the manifold has vacuum, at speed it has positive pressure. If there was an air leak, it would make sense for it to be lean at idle and rich at speed.

Apart from the physical things such as pipes, you're getting into the realms of second guessing as to whether the sensors are reading correctly. Air mass for the air entering the engine, thrust sensor for measuring the pressure after the turbo has gone to work on it and the lambda probe which reports the state of the mixture. Though they're not reporting faults and are reading within their parameters, they could be giving a reading which is incorrect at a particular time.