unicyclerepairman

Wow, was that a manufacturing defect? Sounds expensive, glad you got it fixed.

@DominicSach Yep. A really helpful guy with VCDS diagnosed it as nothing to do with the turbo but as a misfire. I don't know whether it was the plugs or a coil pack, but changing both fixed it 100%.

Just to close this off. I was completely wide of the mark. It was either the plugs or the coil pack - I don't know which because I changed both. I took it to David in Enfield to benefit from his VCDS, but I also benefitted from his experience and advice!

Hi TheClient - thanks for thinking this through, but don't let it bug you! It's been bugging me since it first became a problem about 5 years ago. So, answering your questions: The engine is a CBZB. The shim was fitted in a recall and the ECU recalibrated at the same time, I presume. It worked fine for a number of years and then suddenly developed this problem. For a while it seemed to work better when I removed the shim. I got a replacement actuator, and that definitely worked better without the shim, but now the old unit with the shim seems to be an improvement. I don't think the wastegate is just open or closed. Per SSP485 "If the nominal charge pressure has been reached, the wastegate is adjusted to the position required to produce the nominal/actual charge pressure." I think the stuttering occurs because once the pressure has been reached the wastegate is opening too far and then the pressure drops and then it closes again. So what I really need is to be able to log the revs, load/torque (or some proxy), the charge pressure and the wastegate position. It's a normal wastegate, not VNT. When the actuator is off it is easy to move the wastegate by hand using the lever the actuator rod connects to - and it moves freely. I guess I could remove the cat to get more access to it, but I'm worried about introducing dirt to the turbine itself if I try to clean the wastegate. I guess apart from logging some data, the next logical step is to find someone with a VCDS so I can use it to calibrate it. It remains a mystery why it suddenly developed a fault. I might not do this immediately, but I'll let you know.

Thanks TheClient for your reply. Here's an update. I called Total Turbo Solutions. They were only interested in refurbing or swapping out my turbo. I don't think the turbo itself is at fault, so I don't want to incur the cost or disturb "the plumbing" unnecessarily. Also they didn't think that any calibration is needed after reintalling, when other sources (including SSP 485) suggest it is necessary to recalibrate the ECU when changing the actuator. Perhaps something to do with the ECU learning the voltages on from the hall sensor at the end stops? So I then did more internet research. I read Self Study Programme 485, which extols the virtues of the "electrical charge pressure actuator" and is available here. As my replacement actuator from eBay (a clone, not made by Mahle) hasn't solved the problem I decided to service and reinstall the original actuator and to put the shim back from the recall. I followed the post of VeeFource on 1 Oct 2019 to service the actuator. I found my sensor was moving just fine, so I didn't lubricate it, but I did put silicone grease on all the plastic gears and on the shaft where it leaves the body of the assembly. This made a noticeable difference to how easily the shaft moved. When I reinstalled on the engine I found the wastegate arm itself still moved very freely. I followed the advice in the comments to this YouTube video to calibrate by turning the ignition on and off and then waiting 5 seconds 15 times in a row. This kind of makes sense because the engine opens the wastegate fully and then closed it when you turn the ignition off. But I don't know whether it learns the voltages in the process. The advice in SSP485 is "After replacing the module, the new module must be programmed via Guided Fault Finding / Guided Functions." But I don't have the kit for that. On a test drive the stuttering was still there - accelerating uphill in third from about 1,600 revs. But it didn't seem as bad. I'm getting some high-temp grease following the advice here, as I found connector at the end of the shaft dry and I'm sure I greased it a couple of years ago. (It is behind the heat shield.) On the 1.2 TSI it is not possible to adjust the length of the actuator shaft as it appears to be on this 1.4 TSI. I need to try recording the charge pressure as TheClient suggests but my OBD II dongle is misbehaving. I think I tried this once before but it was inconclusive. I wonder if these sensors ever go wrong. Or if I'm completely misdiagnosing this? Might it be worth getting hold of VCDS to use the "guided functions" feature to recalibrate? Any ideas?

Hi everyone Sorry to return to the topic of 1.2 TSi turbos/wastegates, but my problem isn't quite like others (e.g. here and here) and it has recently left me with limited power in difficult situations (busy uphill dual carriageways). Between 1.5k and 3k revs I get a rapid stuttering (per 5x per second). It can be controlled by easing off on the accelerator and changing down (usually 2 gears). If I ignore it, I get a ping and the EPC, ECL and ESP (Electronic Stability Programme) lights come on amber. All 3 lights always come on together. There is some loss of power, and I need to stop and turn off the ignition to clear the lights. There are no stored or pending fault codes on my OBDII reader. Thinking it must be to do with the turbo pressure building up, then the wastegate opening, then closing and building up again in a rapid cycle, I removed the actuator to see if anything was jamming, but the actuator and wastegate seem to move freely. I removed the shim that was fitted in the recall, and this improves the situation. I recently tried putting it back, but this made it worse. I also changed the actuator with a reclaimed unit from a German dealer. I know that you can't just change them without recalibrating, but I did anyway and it made no difference. The problem appeared suddenly about 5 years ago and I've lived with it since then. Previously I had no problems (or turbo lag), both before and after the shim was fitted. I doubt it actually needs a new turbo and figure that it is just a sensor or calibration. Could an independent turbo specialist do this? Anyone have experience of Total Turbo Solutions? Or am I barking up the wrong tree? Would you try other things first? Any advice gratefully appreciated! If I get it fixed I will have a spare actuator (I forget which length) available.