Beetle Cabriolet Limp Mode

Hi,
Please could anybody help with a problem which seems to be flumaxing all our local garages.
History - Bought 2005 Beetle Jan2018 from dealer. March 2018 dropping into Limp mode (cycling ignition cured problem but happens again not long after) Turbo diagnosed as problem and replaced with recon from reputable local specialist. Fine until late November 2018 when drops into limp mode again, sometimes bringing on engine management light, sometimes not. Took to local garage, OBD indicated cam sensor, cam sensor replaced but same problem. OBD now indicating EGR valve, EGR replaced but still same problem. Garage now sayings it's the turbo. Took it back to supplying dealer who were very nice, as despite car being out of warranty, turbo had a year warranty. They asked for an independent German Car Specialist to inspect and report who also stated it was the turbo. Turbo went back to supplier who couldn't find any fault but cleaned it all out anyway. All reassembled now with sparkly clean turbo, new EGR valve, new Cam Sensor it's had a new Crank sensor too for a different problem.....but no change. Just drops into limp mode when it fancies it. Might be fine for 5 minutes or a couple of days. Sorry for the epic tail but it's doing my head in. Has anybody seen anything like this before? Nobody local appears to have. Any help and suggestions would be massively appreciated. I'm no mechanic but at least I can go back to the garage and say 'Have you looked at this? Thanks in advance for any support. Dave

Limp mode is caused by several things, not just the turbo. The MAF sensor could be getting tired, giving false readings, the turbo actuator could be misadjusted, or their could be vacuum leaks.


Start with the simple stuff. Check for vacuum leaks. At the vacuum pump, you should have a minimum of 20inHg of suction. Make sure there are absolutely zero leaks in the system. The hard plastic line that goes to the brake booster is common for splitting and leaking.


Second would be to check the vacuum actuator. It should hold vacuum and not bleed down. I'm not familiar with the BEW engine turbo (if that's what your engine is) but I know that other turbos, the actuator should start to move at 3-5inHg, and come to a full stop between 16-18inHg.


Thirdly, would be to check the MAF. You'll need VCDS to monitor MAF specified vs Actual. Reading should be within 20mg/s of each other. If your MAF gets stuck at 500 at wide open throttle pulling in 3rd, you have a bad MAF.

Interweb stab in the dark- wiring

Pipework was all checked for leaks when it was last in the garage and is supposedly all good. I thought in for a penny in for a pound, I'll just change the MAF for a shiny new Bosch one. Still no joy. Still no change....still dropping into limp mode. I guess there is only the N75 now that hasn't been changed.....

Did you check the turbo actuator for binding or for operation?

Thanks for getting back to me, it's much appreciated. I may have to pass that one on to the mechanic....I'm ok at undoing 4 screws and a clip to replace a MAP (which is why I thought I might as well give it a go) but the other checks may well be beyond mine (and You Tubes) expertise....Thanks again, hopefully it's being looked at.....again....middle of next week....£500 down and counting.....oh dear...