P0403 & P0234 - clears when restarts

[gsmdo]

Good afternoon all,

I've not been online much, as the convertible has been behaving itself. However, a couple of days ago, it threw a hissy-fit and went into limp mode, with the glow plug light flashing (actually, it went into 'undriveable' mode).

As soon as I restarted, it returned to normal. However, a day or so later I had a similar event, so garaged it until I had time to use the OBD11 on it.

As expected, it started and idled perfectly, but threw up the following codes:

P0403 - Exhaust Gas Recirculation Circuit - Intermittent

P0234 - Turbo/Super Charger Overboost Condition - Intermittent

A bit of googling suggests that the EGR may be blocked or defective. Can anyone suggest first steps to diagnose what needs cleaning or replacing, please?

Many thanks,

Mike 😎

PS Car is a 2006 A4 convertible with a BPW 2.0 TDi 140, manual gearbox and about 107k miles.

 

 

 

 

 

Edited July 18, 2023 by gsmdo

[Steve Q]

You could try and get the egr cleaned out. If you do replace it ndke sure it's a genuine one and not aftermarket rubbish. 

The turbo could have vains broken off. Is there any lag in acceleration? 

[gsmdo]

Thanks, Steve. I can get a genuine EGR from Audi for Around £380 - or an aftermarket one for around £80...🤔 eBay aftermarket link

There is a slight lag in acceleration, not as pronounced as an early Saab turbo, but noticeable; but I thought this might be a function of having the chip breathed on (which enhanced the performance significantly).

I could probably strip down the EGR and have a look at the turbo's vanes this weekend...

Edited July 18, 2023 by gsmdo

[Stevey Y]

1 hour ago, gsmdo said:

Thanks, Steve. I can get a genuine EGR from Audi for Around £380 - or an aftermarket one for around £80...🤔 eBay aftermarket link

There is a slight lag in acceleration, not as pronounced as an early Saab turbo, but noticeable; but I thought this might be a function of having the chip breathed on (which enhanced the performance significantly).

I could probably strip down the EGR and have a look at the turbo's vanes this weekend...

Hi its the EGR thats causing the Turbo problem as its clogging the variable vane bit up with crud, just replace it as if its the original its not worth the time taking it off cleaning it and putting it back on to find it still plays up, what did you have a remap or one of those disaster in waiting tuning boxes.

Steve.

[gsmdo]

Just now, Stevey Y said:

Hi its the EGR thats causing the Turbo problem as its clogging the variable vane bit up with crud, just replace it as if its the original its not worth the time taking it off cleaning it and putting it back on to find it still plays up, what did you have a remap or one of those disaster in waiting tuning boxes.

Steve.

I had a proper remap - from someone a friend of mine has been using for ten years - and I trust his judgement.

I would think, at 107k miles, it might be worth fitting an £80 aftermarket EGR, and then - if it doesn't work out - fit a genuine one? 🤔

[Stevey Y]

22 hours ago, gsmdo said:

I had a proper remap - from someone a friend of mine has been using for ten years - and I trust his judgement.

I would think, at 107k miles, it might be worth fitting an £80 aftermarket EGR, and then - if it doesn't work out - fit a genuine one? 🤔

Hi the genuine item is probably made by another company anyway, probably Valeo or similar why pay so much more for the box, just don't forget to adapt the new unit.

Steve.

[gsmdo]

1 hour ago, Stevey Y said:

Hi the genuine item is probably made by another company anyway, probably Valeo or similar why pay so much more for the box, just don't forget to adapt the new unit.

Steve.

"Adapt the new unit" - could you expand on that please Stevey? 🤔

Thanks,

Mike😎

[gsmdo]

New EGR valve has arrived...

[Stevey Y]

22 hours ago, gsmdo said:

"Adapt the new unit" - could you expand on that please Stevey? 🤔

Thanks,

Mike😎

Hi somewhere on OBD Eleven should be an adaption facility this trains the new unit to learn its values again via the ECU which then thinks ok the units new and cancels the old learned values and starts to re learn its new operating strategy, it can be left and will work it out itself but I have always found the re adaption method cancels any funny running while it learns, your type of valve is not dissimilar to mine and they normally fail because the valve in the cut out leaks excess gas into the engine, nowadays thats known as excessive EGR flow.

Steve. 

[gsmdo]

3 minutes ago, Stevey Y said:

Hi somewhere on OBD Eleven should be an adaption facility this trains the new unit to learn its values again via the ECU which then thinks ok the units new and cancels the old learned values and starts to re learn its new operating strategy, it can be left and will work it out itself but I have always found the re adaption method cancels any funny running while it learns, your type of valve is not dissimilar to mine and they normally fail because the valve in the cut out leaks excess gas into the engine, nowadays thats known as excessive EGR flow.

Steve. 

Thanks Steve - I'll post up the progress with the work... 😎

[gsmdo]

So, after a bit of a gap, I have some news.

It was a fairly muggy but bright day, so I drove the 120-odd miles to my tuner Darrell's place in Northampton with the hood down...😎

Arriving just before 1300, Darrell immediately drove me to the pub and told me to have some lunch and keep myself busy... 😆

Rude not to...

Meanwhile, back at the barn, Darrell has managed to remove the old ERG valve...

Hmmm - that's not supposed to look like that, is it?

Touch of carbon build-up there, Hoskins...🧐

He fits the new EGR valve, then does a deep-clean of the exhaust system and the DPF. He then zeroes all the settings on the remap, and sets the EGR 'duty cycle' to a minimal number - effectively deleting it, but without throwing up error codes.

He picks me up at the pub in a couple of hours, and tells me that the car will need an oil service as soon as practicable - I was planning this for Saturday anyway. He also tells me that the air filter is filthy and asks when it was last changed. I did this in July 22 (and, it later transpires, only 2000 miles ago). I have a fresh one in the garage to be fitted this weekend.

We go for a test drive and the car is quite hesitant at low throttle settings. Darrell assures me that much of this will be the system getting used to it having a valve that functions, but also mentions that the injectors may need a clean. As I need to refuel anyway, I do so with 'Super Diesel', as it promisees extra detergents etc.

Can anyone recommend a good diesel injector cleaner additive?

After settling up, I drive home - once again with the roof down - why not? 😎

By the time I get home, much of the low throttle hesitation seems to have gone.

After releasing my poor dog into the backyard, I quickly pop the bonnet and remove the air filter...

Holy crap!

Darrell says the entire EGR flow has clearly been routed through the air filter to cause this...

I shall complete the service at the weekend and report back with any updates...

Cheers,

Mike 🤓

 

 

 

[gsmdo]

So, I put a bottle of this stuff in the tank today...

 

...and will see if it makes any difference.

 

I also explored the idea of new injectors...

Part no 038 130 073BJ  - £975 EACH - even with my special discount, they are still £795 each... 😱

A bit of searching on eBay reveals remanufactured ones, with a two-year unlimited mileage warranty, for £151 delivered (each). These are exchange parts, with a £65 surcharge, returned on receipt of your injectors. Does anyone on the forum have experience of these guys?

VEHICLO LTD

Marek Jasiok

Unit 2, Hinckley Business Centre

Brindley Road

Hinckley

Leicestershire

LE10 3BY

 

They seem to have good feedback, although their main business seems to be supplying turbos.

I'm going to run a couple of tanks of diesel through the engine, probably adding another bottle of cleaner with the next tankful. I'll then drop over to Darrell and get him to hook it up to his diagnostic gear and data-log the injectors, to see how bad they are.

If they are misbehaving, it'll make a good job to do when the weather is crap (October onwards 😆). 

 

Cheers,

Mike 😎

 

Edited August 1, 2023 by gsmdo

[Stevey Y]

On 7/31/2023 at 7:26 PM, gsmdo said:

So, after a bit of a gap, I have some news.

It was a fairly muggy but bright day, so I drove the 120-odd miles to my tuner Darrell's place in Northampton with the hood down...😎

Arriving just before 1300, Darrell immediately drove me to the pub and told me to have some lunch and keep myself busy... 😆

Rude not to...

Meanwhile, back at the barn, Darrell has managed to remove the old ERG valve...

Hmmm - that's not supposed to look like that, is it?

Touch of carbon build-up there, Hoskins...🧐

He fits the new EGR valve, then does a deep-clean of the exhaust system and the DPF. He then zeroes all the settings on the remap, and sets the EGR 'duty cycle' to a minimal number - effectively deleting it, but without throwing up error codes.

He picks me up at the pub in a couple of hours, and tells me that the car will need an oil service as soon as practicable - I was planning this for Saturday anyway. He also tells me that the air filter is filthy and asks when it was last changed. I did this in July 22 (and, it later transpires, only 2000 miles ago). I have a fresh one in the garage to be fitted this weekend.

We go for a test drive and the car is quite hesitant at low throttle settings. Darrell assures me that much of this will be the system getting used to it having a valve that functions, but also mentions that the injectors may need a clean. As I need to refuel anyway, I do so with 'Super Diesel', as it promisees extra detergents etc.

Can anyone recommend a good diesel injector cleaner additive?

After settling up, I drive home - once again with the roof down - why not? 😎

By the time I get home, much of the low throttle hesitation seems to have gone.

After releasing my poor dog into the backyard, I quickly pop the bonnet and remove the air filter...

Holy crap!

Darrell says the entire EGR flow has clearly been routed through the air filter to cause this...

I shall complete the service at the weekend and report back with any updates...

Cheers,

Mike 🤓

 

 

 

Hi much as I hate to dispute the EGR flow  theory, Darrel is talking Scallops as the EGR flow has no way of back feeding into the air box, what you have there is a years worth of airborne contaminants, the most obvious thing being that exhaust gas is very, very hot and if it was coming back to the filter it would melt the whole thing in short order, I have even seen blocked DPF units that have had holes burnt into them where the hot gas has burnt through a carbonised steel casing to escape, allied to the fact your EGR was blocked and the gas is injected further down the stream before the throttle how was it getting all the way back through the intercooler past the opposing cooled air and back up to the induction trunking, sounds like a bit of a fairy story. If I wanted injectors I would try United Diesels with 30 years plus in the game they are a safe bet.

Steve.

[gsmdo]

12 hours ago, Stevey Y said:

Hi much as I hate to dispute the EGR flow  theory, Darrel is talking Scallops as the EGR flow has no way of back feeding into the air box, what you have there is a years worth of airborne contaminants, the most obvious thing being that exhaust gas is very, very hot and if it was coming back to the filter it would melt the whole thing in short order, I have even seen blocked DPF units that have had holes burnt into them where the hot gas has burnt through a carbonised steel casing to escape, allied to the fact your EGR was blocked and the gas is injected further down the stream before the throttle how was it getting all the way back through the intercooler past the opposing cooled air and back up to the induction trunking, sounds like a bit of a fairy story. If I wanted injectors I would try United Diesels with 30 years plus in the game they are a safe bet.

Steve.

Hi Steve,

I took his answer from a text, "your engine has been breathing in all the EGR gases" - but you're quite right. As regards the state of the filter - it is clogged with obviously carbon based oily dirt. I've never seen a filter fouled this way. It definitely isn't just 2000 miles of airborne contaminants, so I'm mystified as to what might have caused it... 🤔

Thanks for the lead on United Diesels - I'll check their website 👍

 

Cheers,

 

Mike 😎

[Stevey Y]

9 hours ago, gsmdo said:

Hi Steve,

I took his answer from a text, "your engine has been breathing in all the EGR gases" - but you're quite right. As regards the state of the filter - it is clogged with obviously carbon based oily dirt. I've never seen a filter fouled this way. It definitely isn't just 2000 miles of airborne contaminants, so I'm mystified as to what might have caused it... 🤔

Thanks for the lead on United Diesels - I'll check their website 👍

 

Cheers,

 

Mike 😎

Hi Mike still fascinated to know how the EGR gas made it in to an air box system that only allows air in one way, in being the operative term, I have in the past changed filter elements at about 2k-1 month when they have the hay wagons out during the harvest in Autumn, drive behind anything that smokes and is diesel for a couple of miles and that will soon foul it up thats the idea of a filter, ergo the rule of change once a year or with every service whichever comes first.

Steve.

[gsmdo]

Well, an unexpected (and very unwelcome) addition to the thread. I did an oil change this afternoon and, as soon as I took the engine cover off, noticed that everything was covered in a layer of soot...

 

So, some further delving revealed the culprit...

A severely cracked exhaust manifold...😬

Anyone have a spare for a 2.0TDi 140 (BPW) engine?

Mike 🤦‍♂️

Edited August 13, 2023 by gsmdo

[gsmdo]

Update: Audi discontinued these in 2021; they were £580 when available. I have found a breaker with a used one for £150 delivered, and have asked for pics.

If anyone is interested, the correct part number is 038253031L

[alpha omega]

glad you found the culprit, but what a pain.plenty of soaking beforehand to get those nuts and bolts off

[gsmdo]

Found another one - £120 delivered and being shipped tomorrow... 😎

 

Edited August 14, 2023 by gsmdo

[Steve Q]

Glad you got sorted. This the problem now with older Audi's.  They're discontinuing the parts. And it's only going to get worse 

[gsmdo]

Well, managed to get the manifold replaced. Here is the old one...

<Rolf Harris> Can you see where it's cracked yet? </Rolf Harris>

I can't believe how quiet the engine is now - this has clearly been blowing for a while.

Still have a misfire/surge at certain throttles settings, though. I think I may have to look at the injectors over the winter...🤔

Hey-ho - maintaining an ageing Audi isn't for the faint-hearted...😆

Mike 😎

[gsmdo]

Resurrection update...

I left the convertible with Norwich Audi whilst I was out of the country.

So, they replaced all the injectors, plus the loom that powers them. Unfortunately, this didn't cue the cruising misfire.😬

Their Master Tech reckons it's likely to be cams and camshaft followers...😱

I've told them to button it up, and I'll decide what to do next...

Bugger.

 

Mike 🤨

 

 

[gsmdo]

So, just back from my mate Darrell's place, in darkest Huntingdon. We hooked the old girl up to his VCDS emulator thing, and looked at the injectors at various power settings. There's a clear difference in cylinder three, whilst the others are all reading normally. The car doesn't smoke, or use any oil, and - having replaced the injectors, the only culprit left is the cam and cam followers.🤨

So, I'm buying an aftermarket kit - but fitting Audi-supplied bolts (they are stretch bolts). I'm waiting for a callback from my tech to see how many hours this will be.

Anybody know how much more work it would be to replace the cam belt at the same time? He's going to have to re-time the cam etc, so - even though it's a couple of years from being due, I wonder if it might be false economy not to?🤔

 

[gsmdo]

For anyone still interested, I picked the convertible up from Norwich Audi this morning.

They fitted a new cam and cam-followers (aftermarket) with Audi one-use bolts; a new thermostat and - whilst they were in the area, I asked them to fit a new cam belt kit.

My subconscious has blocked out the total cost, but it is FIXED! It runs and drives superbly and is currently back in my garage, where I am going to sort out the double-DIN swap this weekend.

~After that, I'll valet it and plug it into the battery tender to await some better weather...

By the way, this is the kit I bought - everything else was from VAG

https://www.ebay.co.uk/itm/373431911649