Edition 30 - Large Carbon deposits on Injectors

[AnSGTI]

I have a cold start problem on my Edition 30. If the car's been left overnight it will turn over but sounds as though it hunts/struggles for a second then idles normally for a while, but every now and then I get a slight shudder/vibration on idle as well. If the car has been running for a few minutes and is turned off then restarted it starts straight away. Car is an 07 plate with 21K miles on the clock - FVWSH

I'm taking the car in to be checked tomorrow under warranty as I've only owned it a week. I want to be sure I can give the mechanic enough things to check so I have some questions.

I've come from a MKIV 1.8T and every time I used to get in it I could hear the fuel pump prime, I haven't heard my Edition 30 do this once not even on turning the key - is this right? I  never drove any other MKVs or Edition 30s so I have nothing to go against. I'm sure I read somewhere how to check the fuel pressure using VAG-Com, what should it be?

A failed PCV valve has been suggested - would this account for a poor cold start and dodgy idle. How can I check this is faulty, or ensure the mechanic that has a look checks?

Sorry - typical newbie, loads of questions.

Thanks in advance!

[Hurdy]

The symptoms you describe could point to a failed PCV.

They are quite easy to check. If you take off the PCV (Takes 2 mins to take off), wipe clean the pipe ends with a lint free cloth (as they usually have oil residue in them) and then blow in both directions into the pipework. You should only be able to blow through in one direction. If you can feel any "blowthrough" in both directions, then the PCV is faulty.

[gazbutS3]

the mk5 should prime the in-tank fuel pump when you open the drivers door to get in, have a listen next time

[AnSGTI]

Thanks for the replies guys.

No I was listening as carefully as I could this evening, when opening the door I hear nothing. As I say the MKIV was pretty audible when I opened the drivers door and when I used to turn the key to the battery position. Will the pump throw up any error codes if there's a problem?

[AnSGTI]

Well the garage called to say they had checked everything, they said they couldn't fault the car but had adjusted the fuel pressure.

I left the car there overnight last night so it would definitely be cold when first turned over today. I went there this morning just to check it did it when the mechanic turned it over - he agreed something was amiss.

I mentioned the PCV valve but I'm still positive I don't hear the fuel pump prime on opening the drivers door, or turning the key in the ignition. I'm going back tomorrow as they wanted to keep the car overnight and turn it over in the morning to make sure they've fixed it but I really have my doubts

I wouldn't be so  but I've only owned the car a week - at least hopefully I'll be able to claim on the warranty

[vRSAlex]

Did they say how they adjusted the fuel pressure?   

[AnSGTI]

They adjusted the duty cycle - software adpation. It was out on it's specified value.

Car didn't seem to start any better but it seems to be idling much better after a 20 mile run. Guess I'll wait and see what happens next time I start it up.

[AnSGTI]

Well that made no difference what so ever - and the tech's I saw haven't got a clue what it could be. Inherent design of the engine he says, I'm not having that as a reason to sound like a bag of spanners on intial start up from cold. The S3 my dad had used to start up no worries and sound smooth.

I can't believe a 3 and a half year old car with 21K on the clock starts up worse than my old MKIV.

Is it pretty natural when filling with petrol not to be bale to squeeze the trigger on the pump as tight as it can go for maximum flow - it just locks on me and I have to start again squeezing the trigger gentley to about half way and even then it can lock again. I'm putting the nozzle in so it's vertically and not at any angles, I also noticed I'm getting a lot of air escaping when I'm taking the nozzle out of the filler pipe - I thought petrol tanks had breathers so the air could escape this way?

I really do feel like rejecting this car as I've not even had it two weeks and I'm not happy with my latest VW

[Top Cat]

Your nozzle problem is common, a few people on here have had this, its just a matter of finding the correct angle, its down to the pumps you use and not the car.
As for the cold starts, mine has always struggled  (from new)when left for more than 2 days, all i do is keep the key turned that tiny bit longer. 

[stealthwolf]

Is it pretty natural when filling with petrol not to be bale to squeeze the trigger on the pump as tight as it can go for maximum flow?

Depends on the pump. I use only Shell garages and even then, there's differences between the pumps - on some I can fully squeeze the trigger and on others, squeezing too much causes it to cut out.

[AnSGTI]

Thanks for the replies - yeah just done some reading on the pump thing and had come to the conclusion I'm just not used to the car yet. 

If I crank it for longer on the key, the starter motor just ends up running on when the car fires. It's not the catching that's the problem, it's when it does catch it runs very roughly for a split second and is very noticeable from the cabin and even outside of the car but then smoothes out. Simply it's just not a smooth start. I've tried leaving the key in the ignition with the battery on for about 60 seconds before starting but it's no different. I'm getting the odd judder on idle thats felt in the cabbin as well -  I think I'm going to pull the PCV valve myself tomorrow and check it.

My girlfriend commented on it last Saturday and she doesn't know much about cars - it has to be something to do with the start-up process but as there's no fault codes registered the tech responce is it maybe just like that which I have trouble believing.

[john_o]

I can def hear my pump prime on drivers door opening (in fact its a common gotcha what NOT to do when fitting a fuel pump when its apart!)

asides from that, what they are telling you doesnt quite ring true.
Duty cycle is detemined by the ECU, what they may have done is reset the adaptation values but not duty cycle (AFAIK that isnt possible its calculated on the fly by the ECU).
What it may point to though is something like a leaky injector thats dropping the fuel rail pressure when the engines off, so that when you come to restart, it all needs to get up to pressure again before it runs smoothly.
And why it needs a few days to 'leak'

would suggest getting someone close to you using VAGCOM to measure rail pressure at idle, then if possible 1/2/3 days after (to see how far its dropped)
you could also log duty cycle for the injectors (all) during idle and running to see if one of them is 'different'

does the car run smooth and hard to the redline?
you 'could' consider injector cleaner

you should also consider wider issues and get a full diagnostic like compression test if nothing obvious comes up (e.g. head gasket etc)

odd judder at idle can be normal depending on your engine mounts and if your coil packs are OK etc

[AnSGTI]

Sorry I may have got it wrong to be honest, I like to think I know a fair bit about cars but when the tech told me what needed doing I may have got the words jumbled up - how you have phrased the explanation seems to ring true with what I was told they'd adjusted.

No I can't hear the fuel pump prime at all, and I couldn't on the MKV Golf GTI they had in for a service which they also let me fire up. They tested both car after they'd both been sat overnight. The tech put his hand on the underneath of my fuel tank and sai he could feel the pump prime when the door was opened.

I don't have VAG-Com and I live in Herefordshire, I was a member of MKIVs before joining here and there doesn't seem to be any VAG Com user based anywhere near me that could help. I really need to get myself a cable quick smart as I think the only was I can get this sorted is by doing the diagnostics myself the taking it back into the garage and telling them what to replace as they really are a bunch of uselss numpties - I have 2.5 months of warranty left.

I think your theory sounds the best I've heard so far - is there anyway I could test this, what if I turned the key to the battery position, turned it off, then back again serveral times before starting - is this likely to help the system build up pressure by having the pump prime a few times? This way I can see if it's any better and put it down to a fuel pressure problem.

[john_o]

hey no apologies needed 
they cant adjust adaptation only reset it, in fact its advised after doing any mods to the car (e.g. air intake) to see how it adapts.
huge adaptation values indicate there can be an issue, anyway I digress...

you really need VCDS to be able to read rail / pump values, not much you could by turning the key.
The fuel system is 'split'
Theres a low pressure fuel side (in tank pump which you hear running) which feeds fuel to the high pressure side (pump that runs off camshaft/fuel rail).
The hp side feeds the injectors.
So when you have issues you need to diagnose both sides.

the pump priming the low pressure side isnt going to make one bit of difference to the high pressure rail side if you get my drift.
So , no doing the 'key' thing isnt going to make any difference or tell you anything imho.

maybe just take it back to the dealer and say the starting is unacceptable? and push them a bit more...

[AnSGTI]

As I thought, I'd read about these engines having a high pressure fuel pump that runs off the CAM. I thought these engines were fairly reliable so I could see it being a component issue - if the injector wasn't up to pressure on start-up, would you expect a miss fire on the cylinder?

Yeah I think that's all I can do is take it back - the car has only got 21K on the clock and full VW service history on time/distance. The previous lady owner was only doing 6-7K a year. Do you think I'd be best getting a compression check or trying to steer them towards monitoring the fuel rail pressure? As it only does it on cold starts (has to be left for a few hours) the problem is catching it. If the cars started a few times close together, on maybe the third try it will start fine then you have to leave it standing for a few hours for it to do it again on startup. This is why to me a fuel pressure problem fitted as I can imagine the pressure (leaks and) dips once the engines left but builds up after it's been running for a few seconds and stays that way for a few hours.

To answer an earlier question you had before I haven't redlined it to be honest, but it pulls well - I've just been getting used to the car. Once it's moving I can't fault it.

I just don't have any faith in VW and I'm not too sure about the specialists around this way.