Lose of boost at high motorway speeds

[Lak2021]

Hi guys,

I have been reading the threads for a solution to this issue. It's suggested the intercooler is sometimes split and causing lose of boost at high pressures. However, intercooler on this looks OK. Don't know where to start, checking hoses, nothing obvious. Any suggestions would be very much appreciated.

Thanks in advance and stay safe everyone.


Lak

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[LordTJC]

Have you had the fault codes scanned? This is where I’d start.

 

[audifan]

Intercooler does look a bit oily at the bottom. Can you get safely under the car and take a picture of the lower are of the intercooler where the plastic end cap joins to the metal radiator.

This is an example of the split end cap on the intercooler viewed don towards the bottom cap...

A scan preferably using VCDS is also a useful way to highlight the faults.

 

[Lak2021]

Have you had the fault codes scanned? This is where I’d start.

Hi LordTjc,

I haven't had it scanned professionally yet, got a Bluetooth obd2 adapter and car scanner app, doesn't bring up any error codes and no warning lights appear on dash, during or after the Lose of turbo power.

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[Lak2021]

Intercooler does look a bit oily at the bottom. Can you get safely under the car and take a picture of the lower are of the intercooler where the plastic end cap joins to the metal radiator.

This is an example of the split end cap on the intercooler viewed don towards the bottom cap...

View attachment 79154

A scan preferably using VCDS is also a useful way to highlight the faults.

Hi audifan,

I have seen that pic before and read the thread, my intercooler doesn't look that bad, dirty at bottom, but I think that is just dirt from road, the car has no undertray. I will get underneath the car and take better pics of bottom of intercooler. After reading the earlier thread, I was hoping the issue is obvious, but not the case.

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[audifan]

Lack of undertray is not good. All the spray and salt get far easier and quicker onto the engine and components causing oxidation and corrosion. With the boost system being VERY sensitive to leaks you want to keep as much as possible sealed from the elements. Undertray does not completely seal the bottom of the engine but does a good job protecting and deflecting a lot of the rubbish.
Buy yourself a cable from ebay KKL type for £8-10 and download VCDS Lite from Ross Tech and scan yourself with that. Far better than any generic scanner and talks to us in a language we understand.
If the intercooler is intact then the next things to check are the small rubber and plastic pipes that run from the N75 valve on the left engine bulkhead down to the turbo. One normally green is the turbo feed pressure line the other black opens the wastegate. These 2 pipes MUST BE INTACT AND FIT TIGHTLY WHEREVER THEY JOIN. At the age of your car I would replace the braided pipes anyway as they will be very much past their best by now. The other weak point is where the pipes fit onto the N75 valve. One has a right angle rubber fitting that does age and crack or turn to goo. Just connect the new braided hose onto the fitting of the N75 valve and forget about the right angle fitting.

 

[Lak2021]

Lack of undertray is not good. All the spray and salt get far easier and quicker onto the engine and components causing oxidation and corrosion. With the boost system being VERY sensitive to leaks you want to keep as much as possible sealed from the elements. Undertray does not completely seal the bottom of the engine but does a good job protecting and deflecting a lot of the rubbish.
Buy yourself a cable from ebay KKL type for £8-10 and download VCDS Lite from Ross Tech and scan yourself with that. Far better than any generic scanner and talks to us in a language we understand.
If the intercooler is intact then the next things to check are the small rubber and plastic pipes that run from the N75 valve on the left engine bulkhead down to the turbo. One normally green is the turbo feed pressure line the other black opens the wastegate. These 2 pipes MUST BE INTACT AND FIT TIGHTLY WHEREVER THEY JOIN. At the age of your car I would replace the braided pipes anyway as they will be very much past their best by now. The other weak point is where the pipes fit onto the N75 valve. One has a right angle rubber fitting that does age and crack or turn to goo. Just connect the new braided hose onto the fitting of the N75 valve and forget about the right angle fitting.

Thanks,
I will order the cable and get onto the diagnostics part of it. Have been trying to source an undertray but there are scarce,. Especially the one for the diesel with the noise absorbly bottom. I have read about the n75 and hoses coming off it. Done a visual inspection, seems OK but will check each pipe properly to ensure the connections are good. Like u said, worth changing these pipes as they would be worn on a 20yr old car. Will order the cable tonight. Will keep you posted.

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[Lak2021]

1.4 TDI - Loss of Power

Anybody had this one in a 1.4 TDI before? About a week ago, accelerating up a hill the car suffered a loss of power (one minute it was pulling hard - next it was struggling up the hill). Car was like this for the whole journey to work - no power on wide throttle openings but ok on a gentle...

www.a2oc.net

Hi guys,

Just been reading the above thread from 2007, the issue seems very similar to mine. Going to unplug the MAF, run it through situations where I lose power and see what happens, will report back.

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[audifan]

In that case don't think they came back with the result. But only a simple unplug.

This is another reason why a VCDS scan is crucial, as it will tell us if a sensor is reading high or low or intermittent.

 

[Lak2021]

In that case don't think they came back with the result. But only a simple unplug.

This is another reason why a VCDS scan is crucial, as it will tell us if a sensor is reading high or low or intermittent.

I am on it Audifan , ordered the cable, it was a fiver off ebay, will download the software as soon as it arrives.. See what it shows,. I didnt think the Bluetooth obd2 dongle and car scanner app combination was a good diagnostics tool.

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