Turbo Problem - Intermittent Turbo

A

ASHEEN

Member
Can anyone help. My turbo was intermittenet, fault codes read: Turbo Pressure not being met, possible causes: Turbocharger, Wastegate, EGR Valve.

After nearly £700 spent, on New Turbo Charger, New Turbo Sensor, having the EGR valve cleaned, the problem still exhists. Although I must admit, the car does feel much more responsive when it all works, when you switch the car off and on again. Power loss occurs normally from start or when being pushed to accelerate on the motorway. This suggests to me that there is still an underlying electrical fault.

Can anyone help.

Kindest regards
A Sheen.
 
Having had all that work done, I would suggest it's something like a split pressure hose, or perhaps the intercooler is cracked/leaking - both are very common causes of failure to reach proper positive turbo boost pressure.
 
Intermittent Turbo

Hi Dan

There are no leaks from the ineter cooler or the pressure hoses. All have been checked, however the mechanic will do another diagnostics check on Monday, as he did not do it again after all the work was done. When shes ok, shes a beaut to drive, and brings real pleasure to the mind, but when the power loss kicks in, it turns into anger and frustration. Running out of ideas and money......



dan_b said:
Having had all that work done, I would suggest it's something like a split pressure hose, or perhaps the intercooler is cracked/leaking - both are very common causes of failure to reach proper positive turbo boost pressure.
Click to expand...
 
I can't believe they didn't pressure test the system after installing a new turbo - that's crazy.

Ok other causes of boost leaks include a faulty wastegate, a faulty N75 valve and a faulty EGR valve. Again though the mechanic should have thoroughly checked all of these components.

Have you got a 75 or a 90? What was wrong with the turbo initially to require a replacement?
 
Hi Dan,

What is the N75 Valve? Is that the valve that sits either side of the EGR valve?

How is the pressure test conducted? He asked me to rev the car and checked the pressure in all the hoses. The original fault read problem with the turbo or wastegate. So if the problem exhists after all the work, could it be just the N75 Valve all along? How much does that cost?

The original turbo was very sluggish at times, but this one performs much better. Can you help further?
 
The N75 valve is part of the ECU's electronic control of boost system; this is in addition to the mechanical control of boost system provided by the wastegate. If there is a leak in the pressurised system somewhere, basically although the ECU calls for more boost to match the fuel/air/boost map for throttle/RPM/ load, that boost demand can not be met as the positive pressure is leaking away somewhere. Eventually the ECU realises and backs off to avoid damaging the turbo.

Faulty sensors are an issue such as the N75, but again the main cause is positive pressure leaking somewhere. It can be as little as the boost sensor line going to the ECU, but again these should all have been checked if someone was charging you >£750 to replace a turbo.

What was actually wrong with the turbo in the first place? Who diagnosed that it needed replacing? My money's still on a boost leak somewhere, possibly a split hose (of which there are many).

You can do a pressure test with the engine off by pressurising the charge intake system (but take precautions to block off the tract before it goes into the manifold) and simply seeing if or where any air leaks out. Boost leaks are so common on older turbo cars as age, vibration and temperature/oil damage the rubber intake hoses.
 
A diagnostics said the turbo was faulty. Since the newer turbo has been fitted, it has much better performance. A new Turbo sensor has been fitted as well, and a new AIr Flow Meter. Looks like the n75 valve, which Auidi say is a Solenoid valve needs to be replaced. I am not a mechanic, I have just got this A2 Tdi which has had an intermittent turbo since I purchased it in August last year. I am gutted that I spent so much on this car, when all it probably required was this solenoid from the very beginning.

The diagnostic report recorded a P1556 fault code, Turbo Boost Pressure not being reached, possible causes, Turbo Sensor, Turbo or Wastegate. It is really annoying. My mechanic did say the solenoid probably needs to replaced from the beginning. Should have started with this all along.........................
 
Turbo Boost Limit Not Reached

All, After spending £700.00 on a new second hand turbo, New Turbo Sensor, New N75 Valves, the problem is still there, an intermittent Turbo. Could there be a problem with the Inter Cooler? Could it be blocked? The problem is less often than before, but nevertheless, it occurs. Its really annoying.
 
are you sure the second hand new turbo is OK ? is it a variable vane turbo?
when i got my car it had a similar problem, turbo would cut out at approx 65, the garage i bought it from had the original turbo refurbished and i have not had a problem since.
maybe you should think about ringing turbo technics for their opinion.
 
Welcome back Mark. "Feeler" we bought off you still going strong having sorted out the door locking problems (initially a wiring fault and then later a faulty comfort unit on the blink). Now coming up to its service which we are thinking of getting it done at the local Audi dealer since they do a £99 oil change service and a free MOT.

Like you we are looking to upgrade to a TDi (but currently out of our budget) since our other cars are all diesels and on a couple of occassions we nearly put diesel into Feeler but managed to stopped just short of pulling the trigger!
 
Last edited:
glad the car is ok, audi is probably the only place that could sort it out but it could cost a lot
 
You must log in or register to reply here.
Back
Top