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.
 
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...
 
Every few months, I scratch my head and have another go at fixing my A2 and at last, it's paid off.
I've finally fixed the last of the issues.
The air leak that couldn't be found even with a smoke machine was the N80 valve!!

The VCDS test on the valve made it 'tick' as it opened and closed but clearly it wasn't sealing.
The old one could be 'sucked through'.
I tried blowing and sucking through the new £20 Bosch valve (0280142347) and it doesn't pass air.

No hesitation now when pulling away and pulls strongly all the way through the revs.
Absolutely delighted.
 
Every few months, I scratch my head and have another go at fixing my A2 and at last, it's paid off.
I've finally fixed the last of the issues.
The air leak that couldn't be found even with a smoke machine was the N80 valve!!

The VCDS test on the valve made it 'tick' as it opened and closed but clearly it wasn't sealing.
The old one could be 'sucked through'.
I tried blowing and sucking through the new £20 Bosch valve (0280142347) and it doesn't pass air.

No hesitation now when pulling away and pulls strongly all the way through the revs.
Absolutely delighted.
I am pleased for you well done and thanks for posting. I think this N80 has flown under the radar in the past and proving by several posts to be unexpected miraculous cure. Now FSI with poor acceleration = check N80.

Andy
 
Every few months, I scratch my head and have another go at fixing my A2 and at last, it's paid off.
I've finally fixed the last of the issues.
The air leak that couldn't be found even with a smoke machine was the N80 valve!!

The VCDS test on the valve made it 'tick' as it opened and closed but clearly it wasn't sealing.
The old one could be 'sucked through'.
I tried blowing and sucking through the new £20 Bosch valve (0280142347) and it doesn't pass air.

No hesitation now when pulling away and pulls strongly all the way through the revs.
Absolutely delighted.
hi Andrew can i ask a stupid question as I'm new to this
i too have a FSI that struggles to pull when its warmed up, had the head gasket done ect ect and still struggling, perfect when cold.
where can i buy a Pro-boost Valve and a N80 valve.
sorry to be a pain
kind regards
john
 
I'd very much recommend that you get the car scanned. Going ProBoost and replacing the N80 might help, but if it doesn't, you've spent quite a few pennies, and, are no further forward.
I think you should try to identify the fault, before you fix it.
Mac.
 
hi Andrew can i ask a stupid question as I'm new to this
i too have a FSI that struggles to pull when its warmed up, had the head gasket done ect ect and still struggling, perfect when cold.
where can i buy a Pro-boost Valve and a N80 valve.
sorry to be a pain
kind regards
john
Good Morning John,

Proboost is not a valve but a software remap for the FSI ecu developed by the German company Pro-Boost, distribution is through member A2Steve. A forum search 'proboost' will give lots to read.

As to the N80 valve, I would buy one through CreweAudi on here but I have not investigated other aftermarket options if available.

I would heed PlasticMac's advice, you must have spent a lot already and got nowhere. Have a look at the Free Scan Register ..


PlasticMac must be not that far away. Long term I advise looking into buying VCDS, the Lite version is popular, search 'VCDS Lite' on here for more information.

Andy
 
Good Morning John,

Proboost is not a valve but a software remap for the FSI ecu developed by the German company Pro-Boost, distribution is through member A2Steve. A forum search 'proboost' will give lots to read.

As to the N80 valve, I would buy one through CreweAudi on here but I have not investigated other aftermarket options if available.

I would heed PlasticMac's advice, you must have spent a lot already and got nowhere. Have a look at the Free Scan Register ..


PlasticMac must be not that far away. Long term I advise looking into buying VCDS, the Lite version is popular, search 'VCDS Lite' on here for more information.

Andy
Happy to help ...
I'm just off Junc 5 M3.
Mac.
 
Good Morning John,

Proboost is not a valve but a software remap for the FSI ecu developed by the German company Pro-Boost, distribution is through member A2Steve. A forum search 'proboost' will give lots to read.

As to the N80 valve, I would buy one through CreweAudi on here but I have not investigated other aftermarket options if available.

I would heed PlasticMac's advice, you must have spent a lot already and got nowhere. Have a look at the Free Scan Register ..


PlasticMac must be not that far away. Long term I advise looking into buying VCDS, the Lite version is popular, search 'VCDS Lite' on here for more information.

Andy
thanks guys
i have had the car professionally scanned a few times in the last few months and is coming up clear each time ??
dash shows no extra warning lights ect and shows all ok
car starts fine and drives pretty ok until it gets to temperature then under load goes flat?
if you change down and hold the throttle to the floor in third lets say at 50 plus it slowly accelerates but then starts jump and drop revs rapidly until you back off and its smooth as silk again ?
I've been a motorcycle mechanic most of my life and know my way around an engine or the tools but this is a bit of a mystery
 
thanks guys
i have had the car professionally scanned a few times in the last few months and is coming up clear each time ??
dash shows no extra warning lights ect and shows all ok
car starts fine and drives pretty ok until it gets to temperature then under load goes flat?
if you change down and hold the throttle to the floor in third lets say at 50 plus it slowly accelerates but then starts jump and drop revs rapidly until you back off and its smooth as silk again ?
I've been a motorcycle mechanic most of my life and know my way around an engine or the tools but this is a bit of a mystery
There are scan tools, and scan tools. Not all are equal. Needs to be VAG specific.
Just to check, is it run exclusively on 98/99 octane fuel?
Mac.
 
There are scan tools, and scan tools. Not all are equal. Needs to be VAG specific.
Just to check, is it run exclusively on 98/99 octane fuel?
Mac.
yes i only use the top grade as with my bikes ect
as i said I'm a machinic myself for over 40 years and can learn something new most weeks
i love the A2s i have 5 mostly diesel and this fsi was a working project for me but is baffling me with electronics ?
think i will stick to the diesels in future however the petrol fsi has grown on me
 
The FSI is quite rare with very few garages with FSI expertise. You are lucky one such is not that far away depending on where you are in Surrey.


Talk to Gary.

Andy
 
i forgot to add the fuel consumption on this 1.6 FSI is poor around 27 mpg i recon
Your FSI is indeed poorly. Everyday free flowing commuter type journeys low 40's mpg, multiple short slow journeys upper 30's mpg, all motorway/fast A roads low 50's mpg - after 80 such miles I had 55 mpg on the dash the other week.

Andy
 
Should be, (well mine is), 45 mpg mixed driving.
So, all that fuel is going somewhere ...
Mac.
yea i agree
but its not leaking it, and it dont smell or breath heavy either ?
starts smoothly ticks over fine, pulls well when cold, but after 5 or so miles it just wont pull when up to temperature ? back off the throttle and its smooth and crisp again, so you just have to feather the throttle after that to get up a decent speed
tried changing the temp sensor, new fuel cap, checked in-line breathers and fuel line,
checked fuel pump, checked for air leaks in fuel lines and gaskets ect ect
as i mentioned i had to put a head gasket on it when i bought it as a non runner and all is well with the head ect
 
@pfjohnnyt
So still do not see a confirmation that a VAG specific scanner has been used and scan result posted here. People are willing to help you but you have to help us first.
 
@pfjohnnyt
So still do not see a confirmation that a VAG specific scanner has been used and scan result posted here. People are willing to help you but you have to help us first.
I am quite happy to meet halfway between your location and mine, or I can come to you.. VCDS scan's got to be worth a try ...
Mac.
 
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