2.0 TDI BKD Occasional Overboost

[TitaniumTom]

So, this has happened twice in the last fortnight.

Basically accelerating hard onto the dual carriageway it pulls really well to start with and then drops into limp mode. No warnings on the dash. After a restart it will then be fine again, and I can push it right through 4th and 5th up to '70' with no limp or anything.

The code on VCDS is P0234 overboost condition.

If it's just sticky vanes not being used enough I'll live with it, but if there's anything simple I can try that would be good to know.

Cheers
Tom

 

[NHN]

If you leave it, the vanes will blow the turbo & the bill will double or more.

If its the vanes, I've removed cleaned & refitted these numerous times.

Where are you located?

 

[TitaniumTom]

It drives fine most of the time though, so if it's just sticking right at the end of the vane travel I'll just not thrash it so hard...looking back at the code it was at nearly 4k lol. I'll only be keeping the car a few months so can't spend much on it. I could remove & clean the turbo myself if I had the garage space, I've done a few before and have all the tools, but live in a flat with a communal car park now which makes any 'major' car work difficult. I'm over near Ipswich if anyone has a local garage or barn they'd let me borrow...I have a few other car jobs to do as well lol, currently have another car in permanent limp mode due to a turbo fault!

 

[NHN]

Your risk, mine did this & blew, caused a hell of a mess, through intake etc.

 

[JimS3]

It won’t only be overboosting at 4K rpm, it will be just as bad at just over 2k where there is always a boost spike even on a healthy turbo.

If you don’t want to pull the turbo off you could invest in a £3 can of mr muscle oven cleaner and spray it in the hot side and leave it a few hours while working the actuator. Either take the exhaust off the turbo or go through the EGR pipe.

Forte also do a fuel additive that cleans the turbo vanes. I was sceptical when I heard about it, but have had some success with it.

 

[TitaniumTom]

It won’t only be overboosting at 4K rpm, it will be just as bad at just over 2k where there is always a boost spike even on a healthy turbo.

If you don’t want to pull the turbo off you could invest in a £3 can of mr muscle oven cleaner and spray it in the hot side and leave it a few hours while working the actuator. Either take the exhaust off the turbo or go through the EGR pipe.

Forte also do a fuel additive that cleans the turbo vanes. I was sceptical when I heard about it, but have had some success with it.

I have read a bit about the oven cleaner...including someone setting fire to their engine bay with it lol, so was put off trying it really. Can it be done from above on these or would it still need jacking up and done from underneath...I can already hear my neighbours groaning as I drag out the trolley jack and axle stands again...

I'll look into the Forte cleaner though.

 

[NHN]

Forget the socalled cleaners, theyre temporary at best & for most its made no real difference.

Only way is either remove & clean or replace, done enough bkd's myself to be able to advise.

The fact its doing it often enough now means it could blow on any drive now, each use is a risk.

 

[TitaniumTom]

Removal isn't an option currently though, I don't have anywhere to do it and can't afford to pay someone else to do it.

How temporary would the cleaners be? I'll only be keeping it another 3 months max, might only be a week or so if it passes MOT and I can find a Golf GTi to swap with lol... It was never meant to be long term.

They do seem to get good reviews online tbf, and something like Wynn's or Forte should work better than Redex.

 

[JimS3]

Agree many fuel additive cleaners are snake oil and a waste of money, however the innotec cleaner or oven cleaner often do cure the issue.

I did the Mr Muscle clean on one of my own cars, an ASZ engine golf I owned that was going into limp mode with overboost, and it cured it and went on to do another 80K miles before I sold it with no further issue.

It also depends on whats causing the vanes to stick, sometimes due to overheating the slip rings get damaged or a bur on them, sometimes its carbon in the slip ring, sometimes carbon around the vanes themselves.

It may work for you, it may not, but it is easy and cheap to try.

On your engine the easiest way on the drive is from above, you need to remove the battery and airbox and then you have plenty of access on the right of the engine to get to the turbo. Then remove the small pipe that goes from the top of the turbo to the EGR cooler. Its 6mm allen bolts into the EGR cooler and normal bolts (12mm maybe, cant remember!) into the turbo manifold.

Easiest way is to buy one of those WD40 cans with a flip up tube nozzle on it, and then swap that onto the Mr Muscle can, and connect on a length of tube, 3mm vacuum tube is ideal. You then insert this tube down the hole in the turbo manifold, making sure it goes straight down and not sideways into an exhaust port!

Spray cleaner until you you see it foam out the hole a little, leave for a few hours regularly work the actuator and keep topping up the cleaner.

Once it is all back together, rinse off any oven cleaner that may have spilled, it is flammable!
Then take the for a drive, let it warm up a bit and then give it a few hard pulls to redline, normally you get a few clouds of black smoke out the back as it burns off all the carbon.

 

[TitaniumTom]

Fantastic, thanks Jim!