Evening all. I have a PD130 Golf ASZ that I have owned for the last 6 years and have done 100k in it within that time. I've always looked after it and spent money on it regardless. Since I have bought it, I have noticed that it has issues with boost when on full throttle. The best way to describe it is like a power surge. I feel that I get better throttle response with the throttle halfway down as opposed to full WOT. The car is standard engine wise other than a Pipercross filter. The lad I bought it off(who is a friend) had it mapped by someone (name escapes me but a well known map. Poss REVO or similar), but had issues with it blowing the boost pipe off the side mount. One one occasion it actually broke the plastic end cap and he had to replace the intercooler. He then had the car re-flashed to reduce the boost pressure and put it back closer to stock. I thought that it could possibly be a bad map and so to experiment, I bought an eBay ECU from LiveWire. Car is noticably faster and more responsive, however the surge issue remains as does the lack of WOT response. I then had a friend write a map (Dave Howlett - Great guy and very knowledgable) and it was the same. The car is a healthy engine in terms of servicing. I service it myself twice a year with decent parts and the car has never missed a beat or let me down. The turbo is standard (actuator arm is free and has 100% movement), the exhaust is standard, however is from a 1.8T and has an extra centre box and still has the cat. I have replaced all the vacuum lines with Samco silicone ones and done the vac simplification mod and it is still no different. I have a lite version of Vag-Com, however I cant get it to work any longer, but have a generic code reader that shows no faults. I have ordered an N75 valve from Darkside Developments to see if that helps but im now at a loss of what to start looking out for other than the expensive bits. The car is on 170k, and I am not likely to sell it as its too reliable and good on fuel so would ideally like to get it sorted but not have to spend 10x more than the car is worth in parts. Is there anything else anyone can think of that could be causing this issue? Anyone close to North Wales / Chester with Vag-Com that would read the codes,in case my generic reader is missing something for some beer tokens? Thanks all in advance. Kenny
Sticky vanes on turbo? Was a discussion on audisport a while ago about similar issues. Mr muscle oven cleaner is one way to clean them. May not be this, disclaimer time haha
Yeah as mentioned the actuator is free and moves easily and I have cleaned the inside with Mr Muscle. I mean the turbo has 170,000 on it so it could well be pretty worn, assuming it's the original one from factory. Just to mention, it boosts really well in 1st, 2nd and 3rd, but can't get to the limiter in 4th without limp mode. Surges really badly in 5th and 6th and noticeable if going uphill in any gear under load.
As in OP needs boost pressure logging on vcds/vag-com or whatever to see if its over boosting. Some/most obd2 readers won't scan the proprioty vag codes so you need a vcds. If you took the turbo apart you can see that spraying mr muscle up the inlet or however you did it will not get all the carbon out so the VVT vanes can still stick.
Yeah the generic reader is pretty pants. The Mr Muscle was put into the turbo via the EGR blanking plate. I know it's not going to remove 100% of the carbon and oil deposits but the actuator moves freely and its only under load it struggles. Not discounting it could be sticky vanes still, however before I start replacing the expensive parts could do with any cheaper ideas first. Would be great if someone could log the boost and the fault codes with vag com.
The only really reliable method is to strip the turbo and clean the vanes and hope the system isn't worn out,my 07 Audi 3.0tdi allroad has this issue and it go's into limp mode,sometimes with gauge warning and other times not. The other issue is the motor drive on the actuator with eventually fail due to overload....this part cannot be sourced as a spare part for the 3.0tdi you just go and buy a whole new turbo which is crazy expensive. My fix is to cycle the actuator arm on the linkage back and forward several times without the engine running ,the result of this is a don't get limp mode anywhere as much ,it now happens rarely and usually "resets itself" after a few kilometres. Your issue maybe a bit different as it appears your vanes aren't opening fully and sticking hence the problem you have @ higher boost requirement...these parts just wear out to the point that even dissembly and cleaning won't sort it. Good luck,cheers.
Boost and fuel log as Davidut mentioned is the only sure way to pinpoint what the turbo does at the Ecu request under load however a lot can be told from the fault code-usually overboost condition is the Ecu inability to control boost creep-can be due because rubbish remaps, faulty maf, faulty map sensors and underboost when the turbo cannot meet the requested specs due to split boost pipe, worn actuator/stuck vnt ring or also a rubbish map !
As for the turbocharger in the pd 130 engine is a tiny gt1749va which has a dumb control with only a map sensor and n75 solenoid to modulate vacuum system in order to keep the boost control within reasonable specs ! It doesn’t have electronic control/smart actuator- the edc16/17 as fitted to your allroad is a lot more sophisticated than the ancient edc15 found on the op’s car…
So guys, apologies for the lack of update. I finally sorted the issue, kinda by accident. I bought a new intercooler as the standard one was leaking oil. It appears that the intercooler that was put on it was from either a petrol model, or a lower power PD as the map sensor was incorrect. I swapped over the sensors before changing the intercooler and the issues had gone. Saying this, I do still have a small surge at the very top of the rev range near to 3.5-4k rpm, especially in 5th and 6th still. I'm guessing this to be the turbo as the car has had a map to try and alleviate the previous problems. I'm guessing the vanes can't hold the requested boost so looks like I'll either make do, or see if I can replace the turbo if it's financially viable. It's only noticeable at high speed while track driving and that's not that often. Cheers for everyone's suggestions above. Appreciate the time taken to reply.
