Hi guys.

Another issue that I'm struggling with 

We have a 2012 mk Golf1.6 tdi (yes I know this is a Skoda forum but it's the same engine lol)

So this one was purchased as a kind of a project (accident damaged non runner)

During the accident the car smashed it's sump resulting in it losing its oil. 

Any way, new sump fitted, battery charged and it started first time. Phew or so I thought.

Took it out in a test drive, 20m up the road, white / blueish smoke, limp mode and flashing glowplug light. 

Put it on diagnostic and found P0299 Turbocharger / supercharger "A" underboost condition.

So we did a smoke test to rule out any leaks, none were found. Checked turbo and discovered there was play in the shafts so we swapped this out for a replacement (used with low miles - no play in shaft whatsoever and the actuator seems to move freely) and the issue still remains.

We disconnected the battery while fitting the turbo, so when the car was first started it sounded really good. It was only on the test drive it did exactly the same thing. 

So if I disconnect the battery, obviously something resets, the car will idle beautifully rev up ok but as soon as you put your foot down, in comes the flashing glow plug light, limp mode and smoke. Disconnected the battery and again it will idle perfectly, the engine sounds sweet, no knocks bangs or rattles, no smoke whatsoever in idle. If you don't put your foot down at all it will drive perfectly, no smoke etc... It's only when you put your foot down (while driving not just revving)

I have also changed out the n75 boost pressure valve for a known working one. I have checked all the vacuum pipes and they are all OK... I'm clueless now as to where to look next?? Any suggestions would be gratefully welcomed 😊

 

Is it boosting and performing correctly under full boost before going into limp mode?

 

It might simply be one of the hose couplings not engaged correctly and springing apart under boost or missing its sealing ring, it sounds like the intercooler etc has been off during the repairs.

Hi,  thank you for your input. It feels like its going to boost, then jerks back  down to no power and the symptoms as described above. I fitted the turbo myself and double checked, then triple checked all of the connections. The interviewer has not been off at any point.

Many thanks again 

I had this issue with my 2012 CAYC, what a pain - at times this has been undriveable.

 

When limp mode kicks in a quick recycle of the ignition should bring it back in line. 

 

I changed MAP and MAF sensors,  N75 valve and it made quite a difference. 

 

Other than that I have been pumping Forte, Archoil etc thru at every opportunity.

 

6 months down the line it's much better - but I will be buying an EGR Simulator as I'm too tight to fit a new EGR  

Hi and thank you for your reply. Don't egr issues usually throw up codes for egr rather than underboost codes? 

@bigkris I had underboost, overboost and a really loud whistle for months on end. 

 

I checked all the vacuum pipes, actuator and found no errors. 

 

Limp mode was coming VERY frequently, on partial throttle, after a very slight lift and even on a steady throttle - cycling the ignition in Lane 3 is quite daunting for the first dozen times!

 

I figured limp mode could either be EGR, DPF or variable vane turbo related hence the bombardment with Forte and spray EGR cleaner etc. 

 

The only sensor I have yet to fit is the DPF pressure sensor which needs to be coded.

 

What ECU software version is yours running, mine is 8822. 

Although EGR is now blocked on the inlet side of the block, and mapped out ... I still get limp mode during regen.

 

A live scan by VAG DPF shows a constant 100% closure of the EGR, except for a minor flutter down to 0% closure when limp mode is activated. 

 

Why should EGR have this effect when 1) it's blocked and 2) it's remapped out ?

In honestly mate, it shouldn't. Did you have it actually mapped out or use one of those devices that fools the ecu into thinking it was not there?

3 hours ago, bigkris said:

In honestly mate, it shouldn't. Did you have it actually mapped out or use one of those devices that fools the ecu into thinking it was not there?

 

Proper remap and a blank. 

I just wonder if one blank is sufficient. 

 

I'm not sure why egr values are still showing if it has been mapped out. The issues we had were at you said egr related in the end, just put a new one on and the problems have gone. If you have a blanking plate for the other end, I'd be inclined to put it on anyway just to eliminate that side of it anyway.