Vw golf mk5 1.9 bkc overboost

[Joegarcia1992]

Hi guys
New to the forum and need some help as im out of things to check. I have a mk5 golf 1.9 bkc and I have just fitted a new turbo and it's overboosting when revving past 3k. I have tried the map maf and n75 box off another car, adjusting the actuator to 18inhg, fixed all boost leaks. I also blocked of the vac line to the actuator so it couldn't open the vnt and made no difference. Any help would be much appreciated as its really bugging me.

[VAG-Abound]

Is it remapped in any way?

Presumably it feels "limpy" if you disable the actuator. But still overboosts? What fault code are you seeing with what reader?

[Crasher]

Over and under boost feel the same, I suspect you have code P0299 and possibly P0234 as well.

[mickeybo]

60% of defects on vehicles is down to wiring 0r faulty fuse boxes or components not being energised by the ecu switched earth. In your case i would first check out turbo pressure control solenoid which is earthed at ecu b29 switched wire colour blue/black

[Joegarcia1992]

Is it remapped in any way?

Presumably it feels "limpy" if you disable the actuator. But still overboosts? What fault code are you seeing with what reader?

No for some reason it feels the same when disconnected and ye still overboosts. I'm getting code p0234.

[Joegarcia1992]

Iv only got the code p0234.

[Joegarcia1992]

Over and under boost feel the same, I suspect you have code P0299 and possibly P0234 as well.

Iv only got the code p0234.

[Joegarcia1992]

60% of defects on vehicles is down to wiring 0r faulty fuse boxes or components not being energised by the ecu switched earth. In your case i would first check out turbo pressure control solenoid which is earthed at ecu b29 switched wire colour blue/black

Iv cleaned all the earths that are under the fuse box, would it not come up as a code if there was a problem with the wiring?

[VAG-Abound]

Where was the new turbo from?

Over boosting with actuator disconnected would suggest VNT vanes stuck or actuator low limit too high - or sensor failure. Adjusting the actuator may have take it out of range. Can you log the requested and actual boost to see if there is some change?

[Joegarcia1992]

Where was the new turbo from?

Over boosting with actuator disconnected would suggest VNT vanes stuck or actuator low limit too high - or sensor failure. Adjusting the actuator may have take it out of range. Can you log the requested and actual boost to see if there is some change?

I got the turbo from a company off ebay. I did do some live data logging and it's showing that the actual boost is alot higher than the specified. I logged it before and after altering the actuator and it hit the same amount of boost when it went into limp mode. Is there a way to upload pics on here as I have some on my phone of the logs.

[Crasher]

I have occasionally had the map sensors over react to boost and jump straight to 2880mBar which is when the ECU will shut things down but as @VAG-Abound (https://www.vwaudiforum.co.uk/forum/member.php?u=210318) says, that is more like the vanes are stuck shut, perform basic settings 011 at idle and watch the actuator cycle back and forth.

[Joegarcia1992]

I have occasionally had the map sensors over react to boost and jump straight to 2880mBar which is when the ECU will shut things down but as @VAG-Abound (https://www.vwaudiforum.co.uk/forum/member.php?u=210318) says, that is more like the vanes are stuck shut, perform basic settings 011 at idle and watch the actuator cycle back and forth.

I have manually vacuumed the actuator and it moves freely, would that mean the vanes are not stuck?
I may try the actuator cycle tonight and see what happens

[VAG-Abound]

I have manually vacuumed the actuator and it moves freely, would that mean the vanes are not stuck?

If there is mechanical connection between them it would suggest they are reasonably free. If you can pop the actuator arm off of the vane control and wiggle it there should be a tinny rattle at each end as the vanes hit stops IME.

Depending on the quality of the turbo it could just have wrongly configured actuator, oversized turbine / impeller, etc. Was it sold as standard spec, or "uprating"? If not standard it could need a new map in the ECU so that it knows what to ask for / expect along the fuel - air - request - actuator - actual decision tree. And conversely if the car had been mapped to suit a non-standard turbo you could be out of tolerance with a standard one.

[Joegarcia1992]

If there is mechanical connection between them it would suggest they are reasonably free. If you can pop the actuator arm off of the vane control and wiggle it there should be a tinny rattle at each end as the vanes hit stops IME.

Depending on the quality of the turbo it could just have wrongly configured actuator, oversized turbine / impeller, etc. Was it sold as standard spec, or "uprating"? If not standard it could need a new map in the ECU so that it knows what to ask for / expect along the fuel - air - request - actuator - actual decision tree. And conversely if the car had been mapped to suit a non-standard turbo you could be out of tolerance with a standard one.

Iv just double checked and it was sold as a standard turbo for a 1.9 bkc 105 bhp and the car hasn't been mapped. Is there any way to check the map,maf and n75 vacuum box at the back of the engine? Iv just found out that the car I tried them off is also having a problem with going into limp mode 😔

[Crasher]

The MAP should reda circa attmo engine off, 1000 ish mBar.

[Joegarcia1992]

The MAP should reda circa attmo engine off, 1000 ish mBar.

I'll have a check tonight and see. Thanks

[Joegarcia1992]

The MAP should reda circa attmo engine off, 1000 ish mBar.

The saga continues, iv checked the map sensor and its 1090mbar. I spent a whole day on it yesterday and still no where near sorting it. I tried disconnecting the exhaust,new map sensor. I tried adjust the actuator the longest it will go. I tried testing it with no vacuum to the turbo and I got 2530mbar with limp mode, I then tried my myty vac and put 18hg to the actuator manually and drove it and got 2530mbar with limp mode again. I just don't understand how I'm getting the exact same scenario with the vnt open and shut. If anyone can help me solve this I'll send over a PayPal donation as its driving me crazy.

[Crasher]

Now you have moved the actuator I suggest you remove the unit and send it to Midland Turbo for rebuild and calibration, other than that I have no dea how to move forward as people say in modern ��

[Joegarcia1992]

Now you have moved the actuator I suggest you remove the unit and send it to Midland Turbo for rebuild and calibration, other than that I have no dea how to move forward as people say in modern ��

I think that's the only way I'm going to fix this as iv ran out of options. Thanks for advice, I appreciate it.

[VAG-Abound]

Have you tried driving with intercooler feed to manifold disconnected? Something should change, and if it doesn't sensors may be whacky.

I think Crasher meant send turbo and actuator for re-calibration. Assuming you bought a well-calibrated turbo that will just send you back to square one. But if it can't be calibrated it will explain why you've been having problems.

EDIT: Have you wiggled the vane control arm with actuator disconnected and does it feel like something is moving?

[Joegarcia1992]

Have you tried driving with intercooler feed to manifold disconnected? Something should change, and if it doesn't sensors may be whacky.

I think Crasher meant send turbo and actuator for re-calibration. Assuming you bought a well-calibrated turbo that will just send you back to square one. But if it can't be calibrated it will explain why you've been having problems.

EDIT: Have you wiggled the vane control arm with actuator disconnected and does it feel like something is moving?

Thanks for the reply, I have tried one last thing before I remove the turbo. I have taken the I let off to clean and found the egr pipe to from the manifold to the cooler was leaking quite abit. One of the bolts was backed out half way. Do you think this could be the reason for the overboost?

[VAG-Abound]

Doesn't seem very likely - a leak anywhere would more likely cause underboost.

Are you able to lot requested / actual boost? If it actual changes something may be stuck - like sensor or vanes. If it starts off at one level but then shoots too far too fast then something may be badly mapped or calibrated. Adjusting the actuator is unlikely to have helped. Even if it needed doing it'll be hard to get right by trial and error.