Leon Cupra 1.8t No Boost......THERMOSTAT STUCK SHUT

[Gti_Jamo]

So was on the motorway today when I felt a drop in power from the engine, pulled over and had a look to make sure no obvious pipes had come off etc and all was good but still no boost and can't even hear the turbo spool, maybe slightly but does not climb above zero psi on my gauge. Then the power came back momentarily but dissapeared and been the same since. Any of you guys have any idea's? Sticking wastegate perhaps? N75 valve failure? Was thinking if it was a boost leak you would still hear it spool up.

Any ideas will be greatful but will get my code reader on it tommorow. Its an AUQ engined drive by wire!!

[RTechUK]

Could be a numer of things, check codes first.

I would bet its N75 related

[Gti_Jamo]

Hopefully, will check back with codes tommorow!!

[RTechUK]

Hopefully, will check back with codes tommorow!!

[Gti_Jamo]

So got some codes up....

I must add that I bought my code reader about a month ago as the car was running lumpy when cold and sometimes wouldn't start at all and would flash up the ESP light when turning over. Checked it then and showed no codes. This morning it struggled to start but when it did it ran fine with full boost for about 3 miles then it was back as it was not getting above 0 psi. It was the same when I came home, started fine and ran fine for about the same distance.

Todays codes.....

* Pressure Drop between Turbo and throttle Valve (Check DV) P1297

* Engine Speed Sensor G28 No Signal P0322

* Error in Mapped Cooling System (usually temp sensor or thermostat P1296

First of all I checked my DV, which is an £40 ebay effort but have run it for 4 years without hassle and had it off today and is moving as it should.

My N75 was one of those 'J' valves off an Audi S2 but has also been on for about 4 years.

The temp sensor and thermostat were both changed last summer when I did my timing belt.

Anyway hope thats enough info for someone to help me diagnose the problem, i'm and old skool mechanic with limited knowlege on electrical diagnostics so any help will be appreciated.

[Gti_Jamo]

Holy bumpage batman.....

[RTechUK]

So got some codes up....

I must add that I bought my code reader about a month ago as the car was running lumpy when cold and sometimes wouldn't start at all and would flash up the ESP light when turning over. Checked it then and showed no codes. This morning it struggled to start but when it did it ran fine with full boost for about 3 miles then it was back as it was not getting above 0 psi. It was the same when I came home, started fine and ran fine for about the same distance.

Todays codes.....

* Pressure Drop between Turbo and throttle Valve (Check DV) P1297

* Engine Speed Sensor G28 No Signal P0322

* Error in Mapped Cooling System (usually temp sensor or thermostat P1296

First of all I checked my DV, which is an £40 ebay effort but have run it for 4 years without hassle and had it off today and is moving as it should.

My N75 was one of those 'J' valves off an Audi S2 but has also been on for about 4 years.

The temp sensor and thermostat were both changed last summer when I did my timing belt.

Anyway hope thats enough info for someone to help me diagnose the problem, i'm and old skool mechanic with limited knowlege on electrical diagnostics so any help will be appreciated.

First thing to do is get the corrrect N75 valve for the car, you need the F or E valve for your ecu.

2, Get the car smoked tested to check for air leaks.

3 change the crank sensor

4 change temp sensor and thermostat with OEM units from TPS.

[Gti_Jamo]

Both the thermostat and sensor were bought from audi last year with new coolant also. Will change the N75 for its proper one and the crank and temp sensor and take it from there. Cheers for your help.

[Gti_Jamo]

After another inspection it appears the thermostat is jammed shut as the lower radiator hose was stone cold even with the car upto temperature. No apparent overheating though which I find strange. Been using the car past three days too. Got bits coming for it so hopefully have it sorted in next few days.

[danny_p]

on the passat i found the valve head from the wastegate had fallen off,    somehow found it's way into the inpeller houseing and jammed it up nicely