# Cutting out at high rpm. Coil pack?



## peter-ss (Sep 3, 2008)

My car has now, on more than one occasion, cut out at high rpm generally when overtaking, which isn't good.

The first time a Vag-com scan showed up the MAF reading to be low. I did a MAF check and it was low so I bought a new one from Audi, fitted it, and the maximum MAF reading was then normal.

It is still doing the same thing and reporting the same error.

The symptoms are the car sort of missing at high rpm, followed by the ESP light coming on and limiting the throttle.

Flicking the ignition off and on whilst moving clears the ESP light and normality is reumed.

I think it's just a misfire that's upsetting the ESP but wondered if anyone else had experienced the same thing.

I have ordered some new spark plugs just in case there's a duff one but if they don't make a difference the coil packs are next on my list to replace.


----------



## peter-ss (Sep 3, 2008)

Ok, well I've had a rethink on this one.

I went down the thought path of it being a fuel starvation problem, replaced the fuel filter, but it's still the same.

I've changed the spark plugs, just because I've never had them out. They were all nice and brownish in colour as they should be.

So the problem is the same; a short loss of power under hard acceleration resulting in the ESP light coming on and the ECU reporting a low and/or intermittent signal coming from the MAF.

I've been going down other paths as I'm assuming it can't be the MAF as it's a new/reconditioned one from Audi, but maybe I've been sold duff one?

I have just had a run with the MAF disconnected and it runs fine.


----------



## peter-ss (Sep 3, 2008)

Right, well, I'm starting to feel like I'm talking to myself now but I'll continue anyway.

This is the fault that I'm still getting with the new Audi MAF

16486 - Mass Air Flow Sensor (G70): Signal too Low 
P0102 - 35-10 - - - Intermittent

Either I have an air leak, that I can't find, or the Bosch MAF from Audi is duff! I have spoken to Audi and got the expected reply of "we've not had a problem with one before", which doesn't exactly agree with what people on the forum have said about new MAF sensors.

Audi wont replace it without doing a "diagnostic" which will be free if they decided the MAF they've supplied is faulty or will cost me half an hours labour (£55) if it turns out to be something else. Either way if it is something else then it's worth the £55 to find out what it is.

I am booked in on Saturday morning so will keep you informed of the outcome.


----------



## peter-ss (Sep 3, 2008)

Well I've been to Audi this morning. I explained the situation to the service manager, handed him a print out from Vag-com with the fault code and asked if I could go into the workshop when it was being looked at.

My request to go into the workshop was ignored and THREE HOURS later they had fitted a new MAF sensor as they said it was faulty.

There was of course no charge but I can't say that I'm that pleased having to waste three hours waiting for them to diagnose that a part they supplied me with was defective!


----------



## KammyTT (Jun 28, 2006)

good outcome, hope it clears the problem up though


----------



## peter-ss (Sep 3, 2008)

Unfortunately it looks like the problem hasn't gone away after all!

Just given it a bit of hoof and unfortunately the car hesitated badly and then the ESP light came on.

Vag-com is showing up as MAF sensor again but this time the fault is a reading too high rather than too low.

16487 - Mass Air Flow Sensor (G70): Signal too High 
P0103 - 35-10 - - - Intermittent

Really starting to get fed up with this now so any ideas or experience would be greatly appreciated.


----------



## Charlie (Dec 15, 2006)

I had this symptom but without the esp light coming on and it was the N75 valve that was knackered, it could also be the TIP collapsing under load, which would tie in with it happening when you are overtaking.

The N75 is about £60 from the dealer and I can help you with a Forge TIP if it turns out to be that, check all your hoses if possible by getting it pressure tested, Wak has this facility and found 3 on my car ;-( all sorted now and running so much stronger.

I have been squeezing my TIP today whilst fitting my BMC CDA and it feels a bit soft so may be time for an upgrade ;-)

Charlie


----------



## neil.knapp (Sep 27, 2009)

I hope nobody was around while you were squeezing your tip! I'm sure if you squeeze it enough it won't be soft for long


----------



## Charlie (Dec 15, 2006)

:lol: Neil, less than 10 posts and you already have the measure if this place bang on 

Charlie


----------



## peter-ss (Sep 3, 2008)

Thanks for the info Charlie.

The problems confused me now as it was reporting the MAF reading being too low so I thought there might be a leak in a hose letting in extra air between the MAF and the turbo.

It's now reporting it being too high!

Where is the N75 valve?


----------



## peter-ss (Sep 3, 2008)

After reading many posts on here now, I'm confused as to where exactly the TIP is?

If it can collapse under load then it must be subjected to a vacuum, so must be on the air intake side of the turbo? but looking at diagrams and photos it appears to be on the outlet side which is under pressure?

Sometime it's referred to as a Turbo Inlet Pipe and other times a Turbo Intercooler Pipe, so which is it?


----------



## peter-ss (Sep 3, 2008)

I have confirmed that my TIP (turbo inlet pipe) isn't collapsing after having set up a webcam under the bonnet looking at the pipe when the problem has occurred.

Logging with Vag-com, whilst the problem has occurred, shows a sudden alteration in MAF value and at the same time a reduction in injector on time, which causes the sudden loss of power.

I found today that my air filter is damp and the source of the water seems to be the pipe to the secondary air pump. I replaced the pipe from the air filter box to secondary air pump as it was broken JUST BEFORE THE PROBLEM STARTED!

I suspect that under high boost water and / or hot air is being drawn up the secondary air pipe and affecting the MAF. Before fitting a new air filter I'm going to disconnect the secondary air pump and blank off the hole in the air box and see if the problem goes away.

The water theory also fits with the fact that the problem only seems to happen the first time you boot it, if you try and make it happen again, it doesn't, making diagnosing the problem even more difficult.

Has anyone else had this kind of problem before?


----------



## peter-ss (Sep 3, 2008)

For anyone who's not read my previous posts; the problem I've had is a partial or complete loss of power under boost resulting in the ESP light coming and sometimes the EPC light with limited throttle. This was a strange fault as it only happened when the turbo came into play for the first time in a while (generally whilst overtaking!).

A scan with Vag-com revealed a low or intermittent MAF reading, so I replaced the MAF sensor. This didn't cure the problem, so I took my car back to Audi, who supplied the MAF, and they came to the conclusion that it was faulty so gave me another replacement.

This didn't cure the problem so I wondered if it could be the turbo inlet pipe collapsing under negative pressure at high boost. I fitted a webcam looking at the pipe and drove for some time before experiencing the loss of power, but it did confirm that it wasn't the TIP collapsing.

This weekend I decided to have another look into this problem that's been ongoing now for some time. I found that the air filter was wet around where the secondary air pump pipe connects.



















I then started to examine the Secondary air system and found that the pump was also wet and didn't work despite having power to it.










The reason that it is in this state is due to the vacuum operated combination valve that connects the pump to the exhaust being failed in the open state.










You can see that exhaust fumes have been passing the wrong way back down into the secondary air pump and back to the air filter box.










I think that the problem has been hot and damp exhaust fumes being drawn back into the intake system that have been upsetting the MAF sensor resulting in the ECU reducing the injector on time and resulting in the power loss (this can be seen when logged on Vag-com). It didn't happen all of the time presumably because it took a while for moisture to accumulate in the pump.

I have had to improvise today, but to prevent this from happening I have made a blanking plate from a bit of stainless steel and fitted it between the combination valve and the connection to the exhaust ports to stop any more exhaust fumes passing back through the wrong way.



















I have also temporarily blocked off the connection from the air filter box to secondary air pump to prevent any moisture already in the pump from making its way back.










When testing the power supply to the air pump I found that, although the pump is full of water and not turning, it was still being supplied with 12V and pulling current. To prevent it from blowing any fuses, I have pulled out the relay that supplies the pump.










This has resolved what's been a very annoying long term problem for now but I'm not sure whether to reinstate the secondary air system or just get rid of it altogether.

EDIT - I have since refitted the relay, but left the pump disconnected, as without the relay in position Vag-Com sees it as a fault.


----------



## peter-ss (Sep 3, 2008)

Here's some information on the function of the secondary Air System.



1 - Motronic control unit -J220- 
2 - Secondary air pump relay -J299- 
3 - Secondary air pump motor -V101- 
4 - Intake manifold 
5 - Air cleaner 
6 - Combination valve for secondary air system 
7 - Vacuum reservoir 
8 - Non-return valve 
9 - Secondary air inlet valve -N112-

Principle and function

Because of the over-enrichment of the mixture in the cold start phase, the proportion of unburned hydrocarbons in the exhaust gas is higher. The secondary air system improves the afterburning (oxidation) process in the catalytic converter, and thus reduces toxic emissions. The heat generated by oxidisation accelerates the "light off" of the catalytic converter and significantly improves exhaust gas quality during warm-up.

Function

In the cold running phase, the Motronic control unit -J220- activates the secondary air pump -V101- via the secondary air pump relay -J299-. Air is routed to the secondary air combination valve.I n parallel to this, the secondary air inlet valve -N112- is activated and allows vacuum to pass to the secondary air combination valve. In this way, the combination valve opens a passage for the secondary air system to supply air to the exhaust ports in the cylinder head.


----------



## ArcofZen (Feb 10, 2009)

Very interesting.. I have the exact same issue. Under high boost or full/nearly full throttle settings the car would hesitate slightly. This became worse over time (few weeks) and the ESP light then started coming on. After checking the car diagnostic also pointed to a MAF issue (reading low) so I had it replaced.

This worked fine for about a week then the dreaded hesitation came back. I am booked in for a second MAF which will hopefully cure the problem but if not at least I know what the problem might be. The garage are replacing the MAF f.o.c as "Yes even new mass air flow sensors fail, in fact they fail quite often!"

Lets hope we can solve this. I'm surprised that so few seem to have had this fault? Its very annoying and of course more importantly dangerous. I won't be overtaking again until it is fixed.


----------



## sabikeuk (Dec 2, 2008)

I have heard that some people have removed secondary air pump on APX engines, try vwvortex.com forum...

I assume you have solved your issue now? or still cutting out?


----------



## peter-ss (Sep 3, 2008)

After a couple of weeks of faultless driving I can confirm that it was the Secondary Air System failure that was causing the problem.


----------



## appy1968 (Mar 5, 2009)

the problem you had sounds exactly what I was told might happen by WAK, he advised me to remove the secondary air pump pipe from the air box just as you have done.


----------



## maceonline (Jan 11, 2009)

Am I Stupid ! having very similar problems. But......

I can't fine my secondary air pipe? do all tts have them (1.8 225)


----------



## peter-ss (Sep 3, 2008)

maceonline said:


> Am I Stupid ! having very similar problems. But......
> 
> I can't fine my secondary air pipe? do all tts have them (1.8 225)


I don't know whether they all have them but the pipe form the air box that you're looking for is on the same side as the MAF but closer to the front of the car and a bit lower down (the bottom front corner of the air box lid).


----------



## maceonline (Jan 11, 2009)

peter-ss said:


> maceonline said:
> 
> 
> > Am I Stupid ! having very similar problems. But......
> ...


No then they don't, i had my whole box out yesterday, deffo dose't have that pipe.


----------



## sabikeuk (Dec 2, 2008)

maceonline said:


> peter-ss said:
> 
> 
> > maceonline said:
> ...


Audi TT 225 has 2 engine types - APX (older, has secondary pump) and BAM (newer, doesn't have secondary pump).


----------



## peter-ss (Sep 3, 2008)

sabikeuk said:


> Audi TT 225 has 2 engine types - APX (older, has secondary pump) and BAM (newer, doesn't have secondary pump).


That's interesting; If the newer version didn't have it then maybe it was given up as a bad idea?


----------



## maceonline (Jan 11, 2009)

so what year was the BAM in then, coz my tts 2000/2001 and that has the BAM. But yeah that make sense if its not on the new one, must off been a bad idea.


----------



## sabikeuk (Dec 2, 2008)

APX was from the begin so in 1999-2000. BAM since 2000 ...


----------



## Grey skull (Feb 2, 2013)

Hi all..I,m having a problem with my TT when starting from cold there is. A noise from the front of the engine like a leak from exhaust kind of sound.the engine ticks over badly the car stutters and nearly stalls on take off but it only last,s until it warms up a bit then the noise goes,the car runs ok then when excellarating in first it hesitates as tho I've hit the brake instead of accelerator ..was just wondering if it could be the air pump you mentioned ..it's not showing any EML,S on dash thanks


----------



## peter-ss (Sep 3, 2008)

It could be.

I would check the condition of all of the hoses under the bonnet to start with.


----------



## Grey skull (Feb 2, 2013)

Will do..my TT is a 2003 150 roadster will it av this system on it,thanks


----------

