Starting Issues - Hot / Warm / Cold

[Vorlockfoss]

Hi all,

How's things...?

I'm new to this forum, so please forgive me if my issue is dealt with, but I have looked, but cannot find a specific reference.

I have an engine issue that has been ongoing for months.  I have replaced many consumer parts, which I have listed at the foot of this description...

Engine / Car

- 2.0 TFSI 211 bhp (CNDC I think) / A4 B8 S-Line Quattro

Cold Start

- Used to start without issue from cold, but has gradually deteriorated over several months, but is still not as bad as when Warm / Hot.

- When attempting to start, the engine either turns maybe once or twice and fails almost immediately, or turns several times and after attempting to fire a couple of times, bursts in to life & runs without issues.

- Sometimes the EPC indicator lights momentarily from cold start, flashing intermittently, but it usually does not from cold.  If it does indicate then stopping and restarting the engine resets this, but I usually wait for the 'choke' to close.

Hot / Warm Start

- The engine is hardest to start when Hot or Warm, and is particularly difficult to start immediately after putting petrol in the tank; it doesn't matter how much, £10, £50 or full tank.

- On rare occasions the engine starts without issue, maybe 1 or 2 in maybe 30 or 40 starts.

- When attempting the first Hot / Warm start the engine turns maybe once or twice and almost immediately fails.

-The 2nd, 3rd & sometimes 4th, 5th or 6th start attempt is the same.

- The 3rd, 4th, 5th or 6th attempt can cause the engine to splutter for a short moment, but then fail.

- The 4th, 5th or 6th attempt causes the engine to just turn over without fireing.  I must then turn off the ignition in order to start the above process again.

- When the engine does attempt to fire momentarily, depressing the accelerator brief sometimes causes the engine to burst in to life, but this is trial and error and does not always work; this could potentially be a red herring, but it feels real at the time.

- When the engine does finally start, more often than not the EPC indicator flashes intermittently and causes the engine to intermittently misfire both when idling and accelerating.  The only way to stop this is turn turn the engine off and immediately back on again, which clears the EPC issue.  The engine starts without issue maybe 9 out of 10 times when following the last process.

Parts Replaced

- N80 / Evap Valve & Pipes - OEM (Mar 20)

- PCV Valve - OEM (Oct 19)

- Spark Plugs - NGK (Oct 19)

- 4 X Coils - NGK (Oct 19)

- Air Filter - Mann (Oct 19)

Error Codes (TBC)

- TBC - Camshaft Sensor - This was tested at a garage using VAG & I'm told this is ok.  I tried an aftermarket sensor which demonstrates the same or worse symptoms.  I am planning to buy a new OEM Sensor in a week or so.

- TBC - A couple of other codes

I think that about covers it.  Please feel free to ask any questions and I will do my best to answer.

Thank you in advance for your help & advice.

Paul.

:0)

[Magnet]

Hello Paul,

Welcome to the forum, and many thanks for the detailed report on your issue. Without meaning to be patronising, your description of the problem, and actions taken, is certainly the textbook way to do it - but unfortunately such posted detail is rare - so many thanks again. 

Hopefully, someone more knowledgeable than me will be along and offer advice regarding these issues with your specific engine type. Unfortunately, my experience is more broad brush, so I can only comment on possible causes that may apply to other marques and models, but here goes:-

Your cold and hot starting issues may be associated with fuel mixture control - i.e. not rich enough to start instantly from cold, and too rich to do likewise when hot. If (in caps.) this is the case, the problems could be associated with a faulty coolant temperature sensor (if fitted) - normally referred to as a CTS. The CTS is screwed into the coolant system, and senses the temperature and signals a suitable voltage to the ECU which decides the correct mixture for the coolant temperature at that time. Upshot:- coolant cold, then mixture will be set to rich; hot, and weaker. Now if this sensor fails, it usually does so to an average default signal -as if the coolant temperature as someway between cold and normal. Symptoms would then be more difficult cold starting since the mixture would not be rich enough, and too rich for hot starts. 

Possibly the offender with your car???

EPC.and starting issues :- Again very much non-Audi:- worth resetting the throttle position (sensor). Really not sure with your car, but with some non-Audi, it can be as simple as switching on the ignition and pressing the accelerator to the floor 5 times then switching off. 

You mention fitting an aftermarket sensor which you are not happy with. Good! My soapbox time again:- avoid aftermarket sensors (possible exception Bosch) wherever possible. Cost is not king. 

Incase it helps. You can buy genuine VAG parts, mail order at discount, from Discount Audi Parts, Cardiff (or similar arrangement of words) - part of Mon Motors ( Cardiff Audi). No connection - other than having experience their services- and no doubt there are others. 

Anyway Paul, simply some food for thought while others come to your assistance.

Many thanks again for being in touch,

Kind regards,

Gareth. 

 

[Vorlockfoss]

Hi Gareth,

Thank you very much for your in depth reply; there is certainly food for thought.

I hadn't even considered the coolant temperature sensor, but will look in to this.  I will also look at your other suggestions...

I actually reinstalled the original Camshaft Sensor, which did eliminate the affects of the aftermarket sensor (Bilstein I think).

Update: I went out today and although the cold start was as expected, my engine started first time on both warm starts, one at Tesco and the other at the petrol station, which was the major issue I was having.  I will post further updates as the week goes on...

I still haven't noted the engine codes, which I will do tomorrow.  :0)

Thanks again,

Paul.

[Magnet]

Thanks for the update Paul.

Encouraging  - progress? 

Aftermarket sensor and Bilstein? Would that have been branded Febi by any chance? 

If so, disappointing, since I have used Febi cables, and hubs to good effect, and considered them to be one of the better aftermarket suppliers. 

Still, sensors = VAG only - with the possible exception of Bosch. 

Kind regards,

Gareth. 

 

[Vorlockfoss]

Hi Gareth,

The Sensor was marketed as 'Bilstein', so not sure tbh.  I'm still going to buy VAG Camshaft & Coolant Sensors, just to make sure.  I'm also going to get a new fuel filter, just to make sure; maybe even a Cranshaft Sensor too, but will buy that if all alse fails.  :0)

Thanks again,

Paul.

[Magnet]

Great Paul,

Keep the Audi discount route I mentioned in mind, unless you already have a similar source. 

Kind regards,

Gareth. 

[Vorlockfoss]

Hi Gareth,

I was on their website last night actually. I had a browse & they only list generic stuff, like floor mats, so I must assume they don't list everything.

I do buy bits from the Audi Trade Counter here, but not sure if they're discounted. I will ask the one you mentioned for a price & see how it comes back. :0)

Not checked codes yet as I'm first waiting for government announcement in 5 minutes, before I take my dog for a walk.

Thanks,

Paul.

[Magnet]

Hello Paul,

Yes, website does seem to be biased to accessories etc. , but they do offer discounts on (all?) parts. 

Contact is Phil:-

audipartsdirect@monmotors.com

Tel. no. 029 20 547568, although I often have difficulty in getting an answer. Main switchboard no. 029 20 547555 (I think) but e-mail your requirements and reg. no. is probably best. 

‘Taking dog for walk’ ... I understand some ‘enterprising’ dog owners in Spain are renting out their dogs to those wanting to justify being out and about! 

Kind regards,

Gareth. 

[Vorlockfoss]

Hi Gareth,

Thanks for the info, very useful.

Renting out my dog...? Now there's a thought... 😁

Thanks,

Paul.

[Vorlockfoss]

Hi,

Small update:

Thursday and Friday I had issues starting my engine, just as described above.  Today I had no issues for the first 2 starts, i.e. cold & first warm start, but then starts thereafter were as before.

Could this be fuel related, i.e. filter/pump/injectors/other?  When I put the key in the ignition I don't hear the fuel systems 'priming'.  Also, when I try to start as normal the ignition failure is almost immediate; it doesn't even try to fire. However, when I wait 3 or 4 seconds the ignition doesn't fail immediately, but does at least attempt to ignite.  If I do this 2 or 3 times then ignition is successful.

I am at a loss to be honest.  I've had failure after failure after failure, where I fix 1 thing and another rears its ugly head.  I'm starting to get fed up and I don't want my car any more, but I'm stuck with it as I have a conscience and can't just palm it on to another unsuspecting victim...

Thanks,

Paul.

[Magnet]

Hello Paul,

Many thanks for coming back. 

Clutching at straws - possibly fuel pump relay symptoms?? 

Kind regards,

Gareth. 

[Vorlockfoss]

Hi Gareth,

Thanks for the advice.  I'll look at that.

The thing that's confusing me, is that it doesn't appear to be permeant, just 95% of the time.  I'd prefer it if it stayed broken so I could fix it... Lol

Thanks,

Paul.

[Vorlockfoss]

Riiiight.....

After an 8 mile round trip with my dog to the local Audi Dealership (we're allowed excercise once a day...!), I've changed the Camshaft Sensor for a new OEM one & for the first 7 or 8 starts all was brilliant, and I thought "yes, it's fixed, at last...!"; I was elated...!

Anyway, rather than walking away and enjoying the moment, I then tried one more time, and the fault returned, as previously explained.  However, there are 3 initial caveats to that; 1) the fault codes have not returned (yet) (see attached screenshot for codes before I cleared them), 2) the starting symptoms are similar or exactly the same, but, it does start perfectly normally after around 4 or 5 start attempts, 3) starting from cold 'appears' to be rectified & normal...

I'm going to have another go tomorrow & I'll report back here...

I want to either cry, set fire to my car or sell it...

Thanks,

Paul.

[Vorlockfoss]

Mmmm, coolant temperature sensor maybe, as you suggested Gareth... Mmmm

[Vorlockfoss]

Just thought I'd give it a quick go after it'd cooled a little;

1) fail but tried

2) fail

3) fail

4) fail

5) normal start, like it just decided to be normal...

The above is a new pattern...

After some thought & more research I don't think it's the coolant sensor, but I am leaning very much towards the fuel relay, as originally suggested by Gareth above...!  From what I've read & learned, the fuel relay is triggard by the Camshaft Sensor, only after the engine starts cranking. Once the engine fires the Camshaft Sensor passes over control to the Crankshaft sensor.  Now, I have a brand new OEM Crankshaft Sensor, so that is not (should not be) at fault.  It's not the Crankshaft Sensor, otherwise I'd have problems after it started running, surely.  This leaves the fuel relay; I say this because when running there are no issues whatsoever, no miss-fires, no stalls, power delivery is normal. The relay is what trigars the fuel pump to start pumping.  Now, if the pump was faulty then surely I would have issues while running too, would I not...?

This leaves the fuel relay (IMHO)...

Any thoughts, anyone...? 😁

Thanks,

Paul.

 

[Magnet]

Many thanks for coming back Paul. If you are trying relay replacement then it’s worth keeping in mind that relays used may well be common to others for different functions on the car, so you could try swopping from a circuit which is not at fault. 

CTS - have tried replacing this? 

Kind regards, 

Gareth. 

 

[Vorlockfoss]

Hi Gareth,

Thanks for your feedback.

I did initially think about the CTS, but I'm not seeing any temp. issues on my dashboard, so I unwittingly dismissed it. Do you think I should change it anyway...?

I will have a look at the relay & see if I can 'borrow' one for testing purposes. 😁

Thanks again & stay safe.

Paul.

[Magnet]

Hello Paul,

CTS and temperature indications:- 

More often than not (but yours?) the temperature gauge sender is a separate component from the often closely located CTS. Upshot can be that the gauge does not show any abnormality, but the CTS may still be at fault and calling for incorrect fuel mixtures.

As I said, normal failure mode is to set (rather than temperature variable) resistance which is not rich enough for instant cold starts, and too rich for hot starts. Having said that, cars usually start, but only reasonably well, so I would not like to offend your wallet and recommend changing it, and it does not solve the problem. 

Sorry Paul, I’m running out of ideas, but it’s certainly interesting. Not the right word to describe it for you, but...

Could you keep us posted. 

Kind regards,

Gareth. 

[Vorlockfoss]

Thanks Gareth...

No, you're right, it certainly is interesting, and frustrating, and annoying, and stressful, etc. Lol

I'm happy to change the CTS as I'm now not convinced it's the relay.  Since changing the CSS it appears to start well from cold, but still demonstrates some starting Issues when hot/warm, but not quite as severe, and I'm not sure engine heat would affect the relay, unless of course the relay is overheating because of its fault... 😳

I've got plenty of time to think now, so I'll keep researching. 😊

Thanks,

Paul.

[Vorlockfoss]

Hi Gareth,

How's things...?

What are your thoughts on the Cam Bridge & either blocked oil transits and/or missing filter mess...?

Thanks,

Paul.

[Magnet]

Sorry Paul,

Could you clarify meaning of:- 

Cam Bridge.

Oil transits.

Missing filter mess (mesh I guess). 

Kind regards,

Gareth.

p.s. How long had this car been with you before it started being problematic? 

[Vorlockfoss]

Hi Gareth,

My apologies.  The Cam Bridge is the part on the end of the 2 cams that contains the mesh filter that filters the oil before it's fed in to the end of the Cam Shafts for the VVT.  Oil 'transits' was a word I used off the top of my head in an attempt to describe the tubes in the Cam Bridge & Cam Shafts that the oil flows through from the engine to the VVT. 😁

I've had the car for 5 years next month & I had the Timing Chain & sundries replaced around a year & a half after purchase as it went in to limp mode &, I was told, the chain had jumped 3 teeth as it had stretched & needed replacing; I'm a bit more knowledgeable about my car now & would query 3 teeth.  I recently discovered that the mesh I mentioned above is missing (they would have to take the Cam Bridge off to replace the chain) and there are marks on the cam shaft ends that look suspiciously like they could have been made by a wondering mesh...

Anyway, I digress.  The current issues all started just over a year ago and have gradually got worse since.  In an attempt to resolve I replaced the air filter (Mann), plugs (NGK) and Coils (NGK) around 6 or 7 months ago, which made only a slight improvement.  I broke down in October and had to be recovered.  After research I concluded the PCV valve was faulty, replaced it and et voila.  However, I still had other issues.  I tested the new coils by replacing them with the old, but no change.  I had no miss-fires on any cylinder, so concluded the plugs were ok. Around 2 weeks ago I replaced the N80 Evaporator valve, as I was having issues starting after refuelling, but no change, except that it is easier to start after refuelling, so that's good...

3 days ago I replaced the Camshaft Sensor, but that made only a small improvement in starting, but not massively.  I've looked at fuel relay & CTS issues, but my car symptoms & codes (see above) don't fit.  However, they do fit a blocked or faulting Cam Bridge & related 'transits', i.e. codes P0011, P000A and P0341. 😁

I just wondered what your thoughts on this might be...

Just to add, I think the possible 'mesh' damage may have been caused when the previous owner had it (although, I cannot dismiss the possibility of the chain replace garage not causing the damage & not telling me, in order to avoid blame).  The missing mesh could potentially cause a blockage over a long period of time & I think I would notice if the mesh dislodged and was ultimately forced through the Camshaft mechanisms. One thing that gives it away is the fact the car had been towed (attempted); I know this because the towing eye has stripped the thread from its mount & quattros cannot/should not be dragged... All work on the car had been reported to me when I purchased, however, when I got home from my mammoth 4.5 hour drive home, I noticed the front bumper looked odd, like it didn't fit & after an investigation I discovered it hadn't been refitted properly after being removed.  To add, the car was serviced and maintained by the same garage that sold it to me.  At the time of collection, they skillfully missdirected my attention from a couple of others faults, non-locking petrol cap, faulty central locking switch, etc.  I know they did this because when I discovered the faults I recalled their words at the time of collection...  The garage in question has since gone out of business (around 3 years ago) due to further discovered issues.

I'm sorry, there's a lot of waffle, but I hope it affords some form of helpful insight.

Thanks,

Paul.

[Magnet]

Hello Paul,

Many thanks for the helpful additional details. No apologies necessary, it’s my ignorance of cam bridges etc. which is to blame! New territory to me I’m afraid, and in terms of the mesh filter. I was going to suggest a look at the PCV system, but as with most other possible suspects, you seem to have been there done that. 

I feel I am at a loss here to suggest other possible avenues, but one I would have suggested (in better times) would have been to nip it around to your local friendly MOT station and cadge an emissions test, which might just give a better pointer towards the effect, or indeed eliminate fuelling as the culprit. I guess it’s finding such an MOT station now is the problem in these troubled times. 

I asked how long you had owned it incase the issue had come to light very quickly after.

Not that this is going to help you at all, but intermittent faults can sometimes be associated with bad electrical connections. Clutching at straws here, but worth giving all visible connectors associated with fuel and ignition systems a squirt of contact cleaner and a wiggle? 

I know this is not where you want to be Paul, but sometimes it worth investing in an hour’s experience of a trusted independent. Such folks have often come across the same issues before and solved it via. the hard way of try this try that. 

Sorry I’m not helping you, but certainly interested in developments. 

Kind regards, 

Gareth. 

[Vorlockfoss]

Hi Gareth,

Hope all is ok.

I think I may have found the issue.  I believe the Cam Bridge Mesh had disintegrated and part of it found its way in to the VVT Solenoid.  I took the Solenoid Magnet off, turned the engine on the force oil to escape the Solenoid, and a small piece of metal appeared in the oil on the bottom rim.  My car appears to start eat time now, but I now have another issue with an incredibly loud noise coming from either the timing area, one of the pumps, the serpent belt tensioner or the alternator.  I have started a new thread accordingly.

Thanks,

Paul.