UK-POLOS.NET - THE VW Polo Forum

I have just been on holiday for a few weeks in Devon.

On my journey back I was driving my wifes 51 reg Polo 1.9 tdi sport and it started to lose power. I was sitting at 80 mph and when I approached a small hill the car lost power and I was having to drive it foot to the floor to get it up the hill by which time the speed had went down to 60 mph.

Now I am back home and the car seems to be worse. It seems as though the turbo is not giving enough boost lower down the rev range. I can boot it in 3rd gear and it goes but not the way it used to up to 55mph and then it stutters a bit.

I have checked all the hoses and all seem fine. There is no weird noises either.

Is there a way of resetting the ECU on these cars. I own an Audi S2 Coupe and sometimes when this plays up I reset the ECU and it cancels all the fault codes.

Any help would be much appreciated as it is driving us mad. I got out accelerated by an old Peugeot 205 diesel today that shows how bad the car is at the minute.

I have got one of my mates to run off the fault codes on the Polo and this is what it came up with...

17964 - Charge pressure control negative deviation P1556-35-10 - Intermittent
17552 - Mass Air Flow Sensor (g70) open to short to ground P1144-35-00

We then checked Autodata and it came up with these ideas to solve the problem.

For the first one it said Wastegate regulating valve, intake leak, turbocharger defective.

For the second code it came up with wiring open short to earth MAF sensor circuit.

Do any of you guys have any ideas which I should try first to see if that is at fault?

I have cleaned the MAF but I know this could also still be faulty. I was going to purchase a Wastegate Regulating Valve as I had this same problem with my Audi.

Does anyone know the part number and preferably a cost for this part as the car is driving me mad now?

Thanks in advance

Maf is probably the most common cause, The dealers now do a genuine excahnge for around £70. If its been on there for over 50k its probably worth changing anyway.
Usual cause of the boost deviation error will be siezed turbo vnt vanes/fingers. You can strip the turbo and clean out all the soot and get these working again but its quite a job. The solenoid valves that control the vnt actuator and the actuator itself probably need a basic check over before you go pulling the turbo to bits though. Are you absolutely sure the vacuum pipe to the actuator is ok?

Thanks for the reply.

Can you tell me exactly where to find the the vacuum pipe to the actuator and I will give this a go?

I am not used to working on these new cars. I have had Golf MK2's and old Audi's for most of my life.

find the turbo on the back end of the engine. An actuator is bolted to the turbo housing (in this case one that works off vacuum) Follow the pipe from the actuator up to the top of the engine and just make sure its not split or broken. It will run to one of several solenoid valves which could be located in several locations depending upon the year of the car.

If you can get easy access to the actuator then disconnect its rod from the turbo vnt lever and just check that this lever moves freely. If its stuck then you need a turbo strip and clean at best.