Boost Cut !

[prj]

The diagnosis of these engines starts with VAG-COM and a boost leak test.
Replacing knock sensors or other components is stupid and a waste of money, until you have done proper diagnosis.

And yes, this is my way of saying that you should NOT waste money on replacing the knock sensors when they are working perfectly.

[mcandmar]

00561 - Mixture Adaptation
13-00 - Adaptation Limit (Mul) Not Reached
00544 - Maximum Boost Pressure Exceeded
27-10 - Implausible Signal - Intermittent

Seeing those two errors together tells me its a simple air leak sucking unmetered air passed the maf. I've had this twice on mine, first time a leak on the turbo inlet hose, second time a torn rubber hose on the crank case breather. Both were technically a vacuum leak as those hoses dont see any positive boost pressure.

Also seen them on a TT caused by a faulty N75 that wasnt sealing when closed. Should be an easy fix, pressure test the system including the maf to turbo hose, bet you there is a leak.

[4WheelDrifter]

The diagnosis of these engines starts with VAG-COM and a boost leak test.
Replacing knock sensors or other components is stupid and a waste of money, until you have done proper diagnosis.

And yes, this is my way of saying that you should NOT waste money on replacing the knock sensors when they are working perfectly.

I agree. Only I've never used Vag-Com on my 3B. A simple LED does the job.

The only problem is, some people just love to throw new parts randomly at the problem, for some reason. Maybe so they can later complain about how unreliable and expensive these cars are to run.

[rj scotty]

I think I have ruled out a boost leak.

Sorry if I sound abrupt, took me by surprise a bit

http://www.youtube.com/watch?v=1uT3jP5x48s

[Rikki Kitto]

Mine does this sometimes, usually just when heading into oncoming traffic on country lanes Seems to be more when engine is nice and warmed up?

[newsh]

Have you tried the MAF connector yet?

[rj scotty]

Gave it a good wiggle and cleared codes last night. Ive not had boost cut but
I noticed I was only getting 1.2bar max boost on a 1.4 bar chip with 95 ron. i need to put some proper fuel in.

Something similar was happening last summer after long motorway cruises:
Max 0.4 bar boost until ignition switched on and back off again, never did get to the bottom of it

[newsh]

Getting slightly less boost could certainly be down to the fuel.

Seems like you've done the wiggle and cured the horrible cut out though.. To fix it permanently you need to clean the pins properly as detailed in my thread about this issue.

http://www.s2forum.com/forum/showthread.php?t=24544

[Foeglass]

The diagnosis of these engines starts with VAG-COM and a boost leak test.
Replacing knock sensors or other components is stupid and a waste of money, until you have done proper diagnosis.

And yes, this is my way of saying that you should NOT waste money on replacing the knock sensors when they are working perfectly.

I haven't got a boost leak allready pressure tested everything and inspected the T-section on the throttle valve.

i've got a
new wastegate membrane.
a new N75 valve.
Forge 007.
RS2 evo intercooler.
Bosch 044 fuelpump.
LMM.
Lambda sensor,
All coolant and temp sensors replaced.
everything is new and original from Audi.
Sparkplugs,
fuelfilter ect are only 4000km's old,
both ingition amps (don't know the right term for them) are new..
A chipped Ecu. no cats and a 2.75inch exhaust from the downpipe.
Engine sounds and runs perfect. the car hasn't any rain of snow/salt for years.
So no corrosion on ground points ect.
Fuel is Ron 98. never put 95 in it.

Have i missed anything?

Edit: RJ scotty my appoligies for hacking your threat!

[rj scotty]

no apology needed sounds like we are in a similar situation

Decent fuel, reset adaptation and a pin clean is next.

Might put my old AMD chips in as a sanity check after that.

Then I need to find that mk5 GTI :mischeif:

[prj]

Try a different MAF.
When some of these MAF's die, they start reading way too high all the time, causing an excessively rich mixture, and also hitting the load limit in the ECU.

Meaning the symptoms are almost exactly like a boost leak, but actually it is the MAF...
BTDT a few times.

@Foeglass - is your wastegate spring stock? Is your wastegate cap drilled?
I have seen one broken ECU doing this as well, after some crazy "repairwork"... but that should not be very likely.

[lostaudi]

Last few days I've had boost cut problems

S4 AAN standard car

Cold or warm cutting from 0.8 bar up to 1.1 bar then it peaked at 1.5 bar and surged between 1 bar and 1.5 bar

I have replaced the N75 with a manual boost control valve set to 1.1

All is well now never gone so well lol

What I am not sure about is will it do harm just running the manual control valve :/

[prj]

Have you read the fault codes? It's very much possible that for example your timing belt has slipped one tooth, and Motronic is removing boost for that reason.
If you are getting 1.5 bar on a standard car then clearly something is very wrong - wastegate completely screwed down or stiff spring fitted.

And yes, it will do harm, since you effectively removed most of the ECU's ability to control heavy knock.

[lostaudi]

Dont think carbs will help much but what do I know

[prj]

Dont think carbs will help much but what do I know

No they won't, just as removing electronical boost control instead of finding out what is wrong with the car won't...
It pretty much sounds like you have wound down the wastegate spring all the way or fitted a stiffer spring - undo that, and everything will be fine.
If you need more power, chip the car.