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gogsboy

Original Poster:

175 posts

36 months

[news] 
Tuesday 6th September 2011 quote quote all
Wonder if someone could advise.

Basically car had being going great, then after a timing belt/water pump change it was coming up with this code.

Audi fault finding was stopping at the N75 solenoid valve which was replaced.

However it is still happening.

The thing is I can't seem to get it to do it myself but my other half can.

The hoses have all been checked and appear ok.

Have read so many different possibilities, is there a best way to pinpoint the issue, if Audi are coming up with N75 and after changing it's no good, not sure point in trying the same again to end up replacing lost of parts that are not the real issue.

I know the 170 has a reputation for injectors, is it possibly the start of that, is it worth throwing in some reex or similar or is that a no no for this engine.

Any pointers most welcome

Tame Technician

2,315 posts

89 months

[news] 
Tuesday 6th September 2011 quote quote all
Check the vacuum actuator for the inlet manifold flap.

The split inside and cause a loss of vacuum in the system so other vacuum operated item, light the turbos actuator and N75 solonoid dont have enough vac left to work.

gogsboy

Original Poster:

175 posts

36 months

[news] 
Wednesday 7th September 2011 quote quote all
Cheers for that, is there a how to anywhere to identify this.

Would have thought Audi could have pin pointed this?

Tried another garage, they said probably needs a turbo but can't see that as it seems to be ok, just on the odd occasion but doesn't seem to be happening with me

Tame Technician

2,315 posts

89 months

[news] 
Wednesday 7th September 2011 quote quote all
its the only black vacuum actuator on the front of the inlet manifold. Take the small vac pipe off it and test it with a vacuum pump to see if it holds a vacuum, if it dont, thats your problem.

Dealer should have gone straight for this really there is a TPI about it.

That said, they may have already test it and ruled it out.

Large throttle openings at low rpm 1500-2500 will bring on the fault, you probably rev the engine more than your other half hense you dont see the fault.


gogsboy

Original Poster:

175 posts

36 months

[news] 
Wednesday 7th September 2011 quote quote all
Well she is not the best at explaining or remembering what she was doing when it happened.

She gave me the impression she was in too high a gear at first so I tried pulling for low revs in 3rd, 4th and 5th several time and couldn't get it into limp mode.

Today she said it happened when she felt she revved the car too much on a dual carriageway and thinks she was at the higher end of 3rd

The other garage said they did some vaccum test, sounds like it might be one mentioned.

What would be the next port of call if they did carry out this test
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gogsboy

Original Poster:

175 posts

36 months

[news] 
Wednesday 7th September 2011 quote quote all
Called Audi today for few reasons, seen the VOSA bulletin relating to injectors, do you know if this is covered?

This car had one replaced in June, they are saying they will only replace all if another one goes, other opinions seem to differ?

Turns out the car had this underboost fault before and Audi diagnosed EGR, which they never replaced but it was replaced elsewhere.

Obviously it was not the fault as it still happens, again fault finding then stopped them at the n75 which was replaced but it still happens.

Seems this fault finding is a bit of a waste of time, you need to look further than a computer flagging N75 and just go and change it without looking at possible wiring or vac issues.

So assuming Audi would have already done this VAC test when it was in, they didnt confirm this however...maybe the mechanic never bothered!

So over the phone Audi are now saying sounds like Turbo....well first it was EGR...no, then N75...no so now they will go for a turbo, 3rd time lucky, seems a joke they cant pinpoint an issue without replacing various parts first!

Tame Technician

2,315 posts

89 months

[news] 
Wednesday 7th September 2011 quote quote all
P0299 really shouldnt be that hard to fix, it can only be about 4 different things in that engine.

If its got a new EGR valve, N75 and there are no vac leaks, (weather from the know troublesome vac actuator on the manifold flap), or any where else in the vac system, then it is possible the turbo vains sticking and then a turbo is the only fix. But I have to say that is unusual, when turbos stick its usually in the other possition and you get overboost rather than under, so dont be sold a new turbo just yet.

There is a software update to prevent the ECU falsely detecting an underboost situation that isnt there, but I havnt had any success with this fix, we did the update to a few cars that had p0299 intermitantly, they all road tested ok but then came back again with the same problem and further issues were then diagnosed.

You need someone who really knows what there doing to look at it, i find it hard to believe an Audi centre would just put an N75 on without being 99% sure that was the fault, but from your post I have to say I'm not sure they have tested it propperly.

Maybe go into the audi centre and ask to speak to the master tech about it. When you phone them you get a service adviser who doesnt really understand how the car works and just relays 2nd hand what the tech told them.

I would say 90% of 170PD TDI's I have tested with p0299 has either needed the manifold vac actuator or there has been a masive boost leak somwhere like holes intercooler or split hose (you would surely hear this, loud hissing on boost)

The other 10% the engines wouldnt rev to 4500rpm due to either blocked injectors or low fuel pressure, the poor combustion at very high revs meant there wasnt enough exhaust output to keep the turbo spinning and an underboost code was logged. Often customers would even know the engine didnt rev as they changed up well before this point and the only simpton they reported was intermitant going into limp mode.

Go out and give it a drive trying both pulling from off boost 1200rpm in 3rd 4th through the range, and thrashing it right to the red line in 4th 5th, to see if you can make it play up.

If it fails in the low rpm range is likely a vacuum issue or the software needs updating, If the engine wont pull right the way to the red line and ECU notices an underboost right at the top of the rev range you may have a low fuel pressure or blocked injector issue.

gogsboy

Original Poster:

175 posts

36 months

[news] 
Wednesday 7th September 2011 quote quote all
That is what I was thinking, easy fix...seems I was wrong smile

Any idea of the cost of the Vac actuator and time to replace roughly.

I also asked about any software updates but never got much feedback there, would have thought the applied it when it came in with the fault previously.

I then asked to speak to someone higher up the chain, they sounded more knowledgable, he was reading either the report from the tech if that is how it works or from the receipt, he said something like car road tested no fault found, audi fault finding carried out and EGR found to need replacing as leaking oil.

It was then changed elsewhere, I mentioned the vac actuator but not a lot said on that, I asked if the tech would have done tests there first, he just said I assume so....would be good if he could have answered a definite yes or no.

The N75 was put on after fault finding and was told it was faulty for sure but it's looking like was nothing wrong with it at all

There is no loud hissing so would like to think the boost leak was ruled out, would a small boost leak possible cause, I'm told the hoses are all good, but guess can be difficult to pin point some minor leaks.

This one seems to rev up when I have tried it, I actually tried pulling from 3rd down at 1000rpm several times but couldn't get it to play up.

It doesn't feel like a 170, well it feels like one had before which wasn't limping but seemed gutless, then a couple thousand mile later an injector went.

I will have a go again see if can get it to limp with me as asking the other half and she reckons it has happened at the bottom end and at the higher end.

Whats the cure for blocked injectors, do they need cleaning or replacing or does the likes of Redex make a difference.

Have you heard the official take on the injector issue, I'd rather get all them done too given had one go before and this one has already had one go down.

Meant to say Audi first had the car in with regards to underboost around 5k miles ago, if it was the turbo would it not have packed in completely by now?


gogsboy

Original Poster:

175 posts

36 months

[news] 
Friday 9th September 2011 quote quote all
Still trying to get this thing to go limp on me but it's never happening!

Tame Technician

2,315 posts

89 months

[news] 
Friday 9th September 2011 quote quote all
!

Must be fixed then

!

Tame Technician

2,315 posts

89 months

[news] 
Friday 9th September 2011 quote quote all
PS cure for blocked injectors is special ultra-sonic clean. Technicians in a tin are never very effective.

gogsboy

Original Poster:

175 posts

36 months

[news] 
Wednesday 14th September 2011 quote quote all
Must be fixed....I wish...there is obviously something amiss but intermittent....or is it known for these to limp with females only smile


DPX

1,025 posts

85 months

[news] 
Wednesday 14th September 2011 quote quote all
find a long down hill little throttle approx 70 in 6th , bottom of hill gentle accell will put mine into limp .

gogsboy

Original Poster:

175 posts

36 months

[news] 
Wednesday 21st September 2011 quote quote all
What is worst with yours and what codes do you get?

Advice now is to maybe have the turbo cleaned but no guarantee it would work, any thoughts?

Is there not a way of diagnosing these cars properly.

It just seems to be the same over and over, take pot shots at changing various things, only for it to return.

If Audi guided fault finding says EGR and it's changed yet still returns then surely Audi guided fault finding is a little misguided or is it user error?

Cats

607 posts

59 months

[news] 
Friday 23rd September 2011 quote quote all
Mine has suffered with this problem for the last two years on and off. Audi haven't been able to fix it and I can never get it to them when it is in fault. They say that a fault is not logged which I find hard to believe. Lots of different sensors have been replaced but it still does it. I now have a replacement engine and turbo but the fault still comes intermittently, usually after about two hours of driving or especially when I make a brief stop for fuel and then on the next hill it goes into limp mode. This is usually after some loss of boost ie very sluggish off turbo on pick up. The turbo usually comes in at plus 3000rpm with an almighty force but is virtually undriveable.
I use the car to tow and the problem is a lot worse when towing. I usually get by by switching the ignition off and back on again to reset the limp mode. It will go through the same fault for a few miles and eventually it gets over it - very frustrating. The car is usually fine from cold but the performance is somewhat eratic.
I have noticed that I will lose the off turbo performance and as long as I don't try and push the car it will eventually get the performance back but whilst in this situation I have noticed that at idle there is a different bassy sound to the exhaust note and something like a hot oil or component smell coming from under the car but definetely not a burning smell.
The explanation of this problem is very well written by the OP so I will get the car back into my Audi dealership to see if they can check this aspect and check the repair history.

Edited by Cats on Friday 23 September 09:06

Tame Technician

2,315 posts

89 months

[news] 
Friday 23rd September 2011 quote quote all
Tame Technician said:
Check the vacuum actuator for the inlet manifold flap.

They split inside and cause a loss of vacuum in the system so other vacuum operated item, like the turbos actuator and N75 solonoid dont have enough vac left to work properly.
Have you done this.

Its very much the likely cause. I had a 170 in only yesterday, had no faults in the memory at all but customer described limp home mode intermitant. With nothing to go on we checked a few things including the EGR valve which was fine, but when we tested the actuator with a mityvac it would not come close to holding a vacuum.

Part is only about £10, need the inlet manifold off to fix, so labour is 1.0 - 1.2 hours.


Edited by Tame Technician on Friday 23 September 18:33

gogsboy

Original Poster:

175 posts

36 months

[news] 
Friday 23rd September 2011 quote quote all
Tame Technician said:
Tame Technician said:
Check the vacuum actuator for the inlet manifold flap.

They split inside and cause a loss of vacuum in the system so other vacuum operated item, like the turbos actuator and N75 solonoid dont have enough vac left to work properly.
Have you done this.

Its very much the likely cause. I had a 170 in only yesterday, had no faults in the memory at all but customer described limp home mode intermitant. With nothing to go on we checked a few things including the EGR valve which was fine, but when we tested the actuator with a mityvac it would not come close to holding a vacuum.

Part is only about £10, need the inlet manifold off to fix, so labour is 1.0 - 1.2 hours.


Edited by Tame Technician on Friday 23 September 18:33
I passed this info onto the garage so I assume they have checked it, they said vacuum was fine, is one vac test sufficient if it's so intermittent.

I mentioned it to Audi and said when it was in previously surely the techs would have checked this.....there was silence followed by, I'm sure they would have.

When he read out what had been done (at Audi), it didn't actually say VAC test, it just said guiding fault finding...found problem, change part and voila.



Tame Technician

2,315 posts

89 months

[news] 
Friday 23rd September 2011 quote quote all
gogsboy said:
is one vac test sufficient if it's so intermittent.
No.

There are a number of items controlled by vacuum on the engine. A typical vacuum test would be to make sure a line that should have vac on it does. (in the even of underboost they would most likely check the vac pipe going to the varriable vain actuator on the turbo) Vac test can either by just making sure you can feel the suck with your finger, or more acuratly fitting a vac gauge to test.

Even with the inlet manifold flap actuator failed in the manner I imagine it has, the car would pass the above test and show no sign of fault to the technician.

gogsboy said:
I mentioned it to Audi and said when it was in previously surely the techs would have checked this.....there was silence followed by, I'm sure they would have.
To ensure a smooth polished customer service, service advisors are trained to be nice to you and see to your needs, be well presented and polite. Sadly they dont always understand how cars work. So if you ask the service advisor, did they check this, they would anser as above, doesnt mean it has actually been done.

gogsboy said:
When he read out what had been done (at Audi), it didn't actually say VAC test, it just said guiding fault finding...found problem, change part and voila.
GFF means the codes were read, and if any were logged a logical test plan was done to see what caused said fault code. If they said there was an EGR fault, then there must have been, but that doesnt mean it was the EGR fault causing the limp home, could have been an issue with no symptoms, If I disabled the EGR system on your car, you wouldnt be able to tell be driving it, but it would log a fault code to say its not working.

My advise would be, ring your local audi centre explaining that the issue you complained about is still there despite them replacing an EGR component, could they have another look at it, make them aware at the time of booking, you would like to chat to the master tech about it when you bring it in. That way he wont be at lunch when you arrive.

Ask to speak to the master tech, ask him if he would quickly check the actuator for the inlet manfolf flap with a mityvac. You know the internet is full on nosence and misguided fools, but another Audi dealers master tech advised you to check this but you dont have a vacuum pump.


gogsboy

Original Poster:

175 posts

36 months

[news] 
Friday 23rd September 2011 quote quote all
Cheers mate, great information there.

With regards to my talks with the Audi dealership it was not just the basic service advisor, it was someone higher up the chain, forget their exact title but they did seem to know more than your average person that you speak too.

I would have thought they would have covered this avenue as you mention there is a TPI about it, whatever that means smile

Is there some document available explaining that it is a known weak point

Cats

607 posts

59 months

[news] 
Saturday 24th September 2011 quote quote all
TT do you have any experience of Bluefin/Superchips remapping on this engine? Would the remapping overlook any underboost problems and by-pass the problematic performance or if there is a vaccuum problem would the performance still suffer?
Bluefin suggest some very good performance enhancement figures for this engine (+40bhp) which I assume are achieved by by-passing certain sensors etc.
I have always found the power delivery of this engine rather disappointing - very much on or off and not smooth and am considering this route but I guess that a vaccuum fault realistically needs correcting first.
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