FSI slow to rev

The first thing I should mention is that for the first few minutes after starting, the car runs fine.
I'm assuming that it runs on some sort of base map.
As it warms up, it struggles to rev freely and feels flat.

VCDS returned the following codes:

17428 - Fuel Pressure Regulation
P1020 - 35-10 - Control Range Exceeded - Intermittent
17579 - Angle Sensor 2 for Throttle Actuator (G188) Implausible Signal
P1171 - 35-00 -
17796 - Control Module Malfunction - DBW Throttle Monitoring
P1388 - 35-10 - - Intermittent


I changed the in-tank pump for a new (Euro Car Parts) one and swapped the throttle body for an eBay one. No difference.

I then took the car to a local Audi specialist who were absolutely fantastic.
However, they failed to find the issue and could only suggest an inlet manifold strip down and replacement of sensors.

This is from the garage's job sheet.

Running faults including lack of power, lack of acceleration.
No definitive error codes. various components replaced (used) prior to receipt of vehicle.
Checked lambda values at idle = perfect (including with AMM discnt)
- Occasionally lambda values run very lean (specified/actual)
- prompted an air system examination
Vacuum circuit proven ok, intake manifold flap lever and solenoid ok.
Base set throttle (did take several attempts but successful)
Base set EGR - OK
Unable to regenerate readiness code. Stuck on manifold position however, as above, did test ok.
ODIS and ERWIN consulted
Error code 17796 did occur during a drive, remedy is to renew ECU!
- substituted ECU with known one. No difference to symptoms.
- error has deleted and not returned.
Checked delivery pressure - ok. No test for high pressure system.
- High pressure fuel pump appears new
Cambelt timing checked - both cams - ok
Air mass meter replaced to no avail £167.09
It is possible the engine speed sensor is faulty and delayed in responding to ECU.
We have experience with faulty sensors on A2 although the issue normally records misfires.
Customer agreed replacement of sensor £95.57. Fault remains.

At this point it was getting expensive so I've put the car in my garage and removed the upper inlet manifold.
I was hoping to see something obvious leaking/split but i can't so I'm considering changing sensors.
I've already replaced the intake manifold flap air flow control valve which leaves the intake manifold flap potentiometer and the intake manifold pressure sender on the manifold.
There are also two sensors on the lower intake. A fuel-pressure sender and a fuel-pressure regulating valve.

Do these sensors fail often?
Can they be tested?
Are they only available from an Audi dealer?

Any suggestions would be most welcome.
I'm really missing 'The Hippo'.
 
The Pro Boost ECU has fixed the problem!

The reluctance to rev below 3000rpm when warm has gone.
This is the best the car has been since I got it.
It even picks up from just over 1000rpm in fifth gear at about 30mph.
I just get one error code which I was getting before the ECU swap.

17912 - Intake Air System
P1504 - 35-00 - Leak Detected


I've probably cracked a plastic pipe or not fully connected one when reassembling the upper inlet manifold.
It makes it a little hesitant when pulling away so that's my next job.
 

dj_efk

A2OC Donor
Proboost is fast becoming a go-to first step for FSIs with running issues at this rate!

Glad you’re sorted and happy - sounds like this is yet another FSI that’s been spared the fate of so many if it’s poorly running brethren...
 
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