Audi A4 B6 (2001 - 2005) - 01 1.9TDi loss of power when accelerating | Technical matters | Back Room Forum

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Tue 29 Dec 2009 11:04

01 1.9TDi loss of power when accelerating - ashflash

Hi all new to this so please bear with me!!
Can anyone help with my A4 1.9 tdi awx engine 2001 140k?

Car drives ok from start up especially when cold, however once you get in to fourth gear and accelerate the engine goes limp and won?t go above 3000 revs in any gear. There is no engine management light on.

I have changed I think it?s the n75 sensor, removed and de-coked the turbo, I have tried fitting a second hand turbo, and tried a new mass air flow meter, all to no avail.
#
Can anyone suggest where else to start looking? Could it be an injector problem? I do feel a judder every so often though not necessarily when it goes limp.

Many thanks ash

Edited by Dynamic Dave on 29/12/2009 at 14:28

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Tue 29 Dec 2009 11:17

01 1.9 loss of power when accelerating - craig-pd130

A couple of questions ... does it accelerate as normal (that is, quite strongly) up to 3K rpm, and then go flat?

When it's gone flat, if you drop back to 2000rpm will it then accelerate strongly up to 3K?

Does it "reset" itself when you switch the engine off?

It's interesting you say it works fine when cold. Maybe suspect the coolant temp sensor, these can give problems but I wouldn't have thought it would be THAT bad.

It shouldn't be the fuel temp sensor, if these go faulty the car still goes pretty well.

Let us know ...

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Tue 29 Dec 2009 11:54

01 1.9 loss of power when accelerating - ashflash

Hi craig thanks for the reply.

Yes it accelerates quite strongly in first three gears revving up to maximum revs. however it is when I go into fourth gear it goes limp and then takes forever to reach 3000 revs or around 80mph.

It does reset when the engine switches off.

Do you think it could possibly be the EGR valve ?

thanks again ash

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Tue 29 Dec 2009 13:05

01 1.9 loss of power when accelerating - craig-pd130

On the pre-2003 cars you can disable the EGR valve without getting a fault code (I ran my 2003 Passat with the PD130 engine with EGR disabled for 10,000+ miles).

Remove the engine cover and simply loosen the clip on the vacuum hose that connects to the EGR valve. Pull the hose off, then find a screw or similar with a head that fits snugly in the hose to block it off. Then reconnect the hose. This completely disables the EGR so you can see if it makes any difference.

The other thing is, have you checked / replaced the boost pressure sensor on the large plastic inlet trunking at the back of the engine? If that is faulty, it could be registering overboost and putting the engine into limp mode.

I would have thought you'd get a "check engine" light with your symptoms but maybe not. Have you checked for any ECU error codes?

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Tue 29 Dec 2009 13:56

01 1.9 loss of power when accelerating - ashflash

Hi craig thanks again, I have had the ECU codes looked at by a mate who works at audi, and on of the errors that threw up was overboost which led him to advise me to change the turbo, but as they are £600-£700 I decided to clean mine and then try a second hand turbo all with no joy. (didn't fancy forking out for a new turbo until 100% sure!!)

I think I will give it a go changing the boost pressure sensor as this could be a likely cause. Any Ideas how much they are? Thanks again ash

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Tue 29 Dec 2009 14:26

01 1.9 loss of power when accelerating - craig-pd130

no idea of cost but it's a simple job, two screws and it's out. They made millions of the things so can't imagine it'd be too much.

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Tue 29 Dec 2009 15:06

01 1.9 loss of power when accelerating - ashflash

ok thanks again going to try and get hold of one tomorrow and give it a go

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Thu 11 Feb 2016 06:56

01 1.9TDi loss of power when accelerating - jonnyaudib6avant

I have the same problem with my b6 avant! But its after i go over 80mph it feels like the turbo cuts out, then like u said ash when i accelerate theres no power at all like the turbo doesnt kick in! Did the boost sensor work for u

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Fri 12 Feb 2016 22:16

01 1.9TDi loss of power when accelerating - Big John

Does it shudder a bit when turning the engine off?

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Sat 13 Feb 2016 10:37

01 1.9TDi loss of power when accelerating - Railroad.

Sounds like classic sticky turbo vanes. What side of the turbo did you clean? Was it the exhaust turbine or the intake compressor side?

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Sat 13 Feb 2016 11:07

01 1.9TDi loss of power when accelerating - Big John

Sounds like classic sticky turbo vanes.

Agreed, but always worth checking for a vaccum leak somewhere in the pipes that feed solenoids for EGR, Turbo variable vanes and antishudder valve. Either the flexible hoses can rot/fail or the small hard pipes can rub through from the diesel vibration - The pipes are a common fail and an easy cheap fix. Many a person has had the turbo changed to find fault still present.

One symptom can be a shudder as you turn the engine off as there isn't enough vacuum to operate the anti shudder valve visible at the top of the engine (drivers side). You can see it operating without removing any covers/parts (hence my question above)

On my 2003 Superb I pd (same engine/layout) one of the hard pipes had rubbed through and as well as the shudder on turn off - it kept going into limp home (eventually putting on EML) especially on a motorway. Managed to keep some restricted speed up on the level but up-hill on the A34 lorries were coming past me! Turn the engine on /off all was well again for a while!

Edited by Big John on 13/02/2016 at 11:14

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Mon 22 Feb 2016 14:15

01 1.9TDi loss of power when accelerating - jonnyaudib6avant

I have no shudder with mine just when i go over 3k revs or 80mph the turbo seems to cut out and i cant get it to go over 2k revs after that unless i turn of the engine and restart it! Now i have also started hearing a rattling noise when i release the accelerator, any clue on what that could be?

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