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Thread: 2.0 FSI Poor idle when cold

  1. #1
    Join Date
    Mar 2009
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    Goulburn NSW
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    2.0 FSI Poor idle when cold

    After my daughters Golf left her stranded for a while Ive swapped my trusty SAAB for her dubious Golf

    Ive got most things sorted out from door locks to faulty light switches, broken wires etc. But I am stumped on this one.

    When starting from cold.

    fires almost straight away revs shoot up and drop to around 1200RPM where it stays for almost exactly 30seconds, duringing this time the idle is lumpy and will on occasion miss fire a number of times but not always. If you try to drive off in this time - you just dont it drives terrible.

    after the 30 secs idle drops down to around 800RPM and smooths out considerably and all is well. Although it it could be better but its not bad.

    stop the engine and restart and idle almost imdeiately settles at around 800RPM and is relatively smooth.

    This occurs both in the morning when its cool around 17deg or so and the afternoon when its around 30deg.

    VCDS scan shows
    Nox sensor Low flow (this only shows up after going for a drive)
    MAP thermostat open circuit
    Evap flow issue ( because in hunting for a solution I found the evap purge valve to be open all the time. I have plugged the pipe to stop the leak while I wait for a new valve to arrive)

    Here is a couple of graphs Ive made from the VCDS logs which show the issue nicely the dodgey section is the first 30 secs the second rise in the idle speed at around 40 seconds is me intentionally raising the RPM to around 1200 to see what effect that has on timing etc.
    The low manifold vacuum and extreme timing retardation is what stands out to me but the question is why?
    2.0 FSI Poor idle when cold-poor-idle-rpm-jpg
    2.0 FSI Poor idle when cold-poor-idle-timing-jpg

    I had been looking for Vacuum leaks and found a couple - Evap purge solenoid and the PCV tubing which I have plugged with no noticable change.

    The 30 second duration seems to be possibly the length of time the ECU runs in MAP mode before changing over to a closed loop mode and taking care of the problem.

    Ive been continually frustrated by the lack of information about the non turbo variant of the FSI motor - if anyone can point me to some detailed documentation or offer some ideas I would be very greatful.

    Im thinking perhaps it is a sensor giving bad data but with limited detailed documentation it makes it a bit tricky. Everything Ive seen just refers to VAG Self diagnostic procedure xyz.....
    THE VAG self study articles are great for an over view but thats about it.
    Last edited by saabman; 25-02-2019 at 10:03 PM.

  2. #2
    Join Date
    May 2017
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    Melbourne
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    I would have guessed a vacuum leak around the PCV, but it sounds like you've already checked/addressed this. My 2.0T started doing this type of thing when the hose connecting the front PCV valve to the intake manifold cracked. Looking at photos of your engine, it looks like the PCV valve tubing is linked to the crankcase and intake manifold in a similar way on turbo and non-turbo engines, although the design of the valve itself is a bit different.

    If you can get the parts cheaply enough, it might be worth replacing the valve and all the tubing as a precaution? The 2.0T engines have tonnes of aftermarket replacement options for their front PCV systems, including cheap 'delete' plates that seal the openings in the crankcase and the manifold, but I don't expect you'd be so lucky with a non-turbo FSI.

    The turbo engines also have a PCV tube with a check valve on the back of the engine, which is prone to splitting. I'm not sure if yours has something similar. It's odd that the engine returns to normal after misfiring at idle; I'm really just speculating here, so I hope you find an answer! A quick Google search suggests lots of Audi A4 owners have had similar issues - could be worth investigating?

  3. #3
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    Mar 2009
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    Goulburn NSW
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    Thread Starter
    I did identify a leak in the Evap purge valve and the PCV system - those plastic pipes have gone a bit stiff and dont seal. For the time being I have blocked both ports. ( my new Evap valve arrived today)

    The problem does seem to be quiet well known about but no definitive answer some have reported dirty inlet valves, PCV, Evap, EGR, temp sensor even a remap.

    I pulled the upper part of the inlet manifold of today to have a lok at the valves, getting the lower part off is a bit more trouble than I want to go to. I was able to get a flexible scope down to the valves for a look and while there is a bit of gunk the seats are clean and I cant see anything that looks like it would create an issue. Ill give then manifold a clean out and leave it at that.

    I pulled the egr valve out as well and cleaned it but again it wasnt bad or sticking.

    the thing that beats me is why the ecu is pulling the timing back to 25deg ATDC.

    I did think the manifold vacuum could have been a dodgey MAP sensor but Ive hooked up a vacuum guage and get the same readings. I need to have a lok at the cold start ecu map and see why its calling for such retarded timing.

  4. #4
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    May 2016
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    Melbourne, Victoria
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    My 2.0 FSI does exactly the same thing, unfortunately I have never found the cause. Hopefully you can get to the bottom of it!

  5. #5
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    Well after a weekend of looking into it Im none the wiser

    I planned to pull the manifold and clean the intake valves - but after pulling the upper part of the manifold and discovering to get any closer to the intake required pulling the lower part of the manifold which contains the tumble flaps and high pressure fuel rail. I did get to have a good look at the valves and they realy wernt that dirty - there was an amount of build up but nothing that I could see causing any adverse effect. I have a flexible "bore" scope I used to have a close look and could get into the cylinder through an open valve and have a lok around. Everything appears to be ok as far as I can tell.

    There was a fair bit of crud (oil + exhuast residue) inside the manifold so gave it a good degrease and clean out cleaned the MAP sensor( It was full of oil) cleaned the throttle body throughly.

    I also pulled the EGR valve out and scrubbed it clean.

    re adapted the throttle and egr valve and starting the car I Was greeted with the same crappy idle

    I did notice though looking at the throttle figures a slight anomaly, Ill put together a graph of the figgures but basically the throttle position sits at about 17% until i depress the throttle it stays put for a little bit then drops to about 12% before opening back up again. Ill have to have a closer look at what is causing that.

    Given the rate this idle thing occurs Im going to have to leave it be for the time being, ive got some other little issues to deal with before I hand it back to my daughter. lights and things nothing significant..

    while I have it im drivingto and from work every day and will continue to log everything I can in the hope i find an anomaly that will point to a failure. Its quiet frustrating as it didnt do it when she first bought the car, We know its not normal.

    Maybe its a problem on the exhaust side?? Ill have to spend some time logging the exhaust sensors.

    On a nother note the new Evap solenoid arrived on friday but I go to fit it and, nope the 2.0FSI uses a different one to every other Golf - this BLX engine must have been made just for the Australian market out of junk left in the VW factory!! the bosch units every one else use apart from fits in backwards, uses a slightly - and I mean slightly, different connector

    It appears parts and documentation for this engine in a Golf just dont exist..... I can can buy new parts for my SAAB's easier than this golf and my SAABs are older and SAAB don't even exist anymore (NEVS just own all the IP)

    My Kombis and beetles are even easier to buy stuff for....

  6. #6
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    Mar 2009
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    Goulburn NSW
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    Thread Starter
    Oh If anyone is looking for a purge vale for a 2005 2.0FSI this is the only one Ive found that looks right.

    2.0 FSI Poor idle when cold-purge-valve-jpg
    NEW Fuel Vapor Canister Purge Valve For VW Jetta Golf MK5 Passat B6 EOS 2.0FSI 987792492926 | eBay

  7. #7
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    Mar 2009
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    Goulburn NSW
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    Thread Starter
    Just a bit of an update on my investigations.

    Typically the poor idle at start up happens in the morning. And sometimes of an afternoon but not always. After thinking about the frequency of the event occurring I’ve worked out that the days it doesn’t play up of an afternoon is when I’ve been out at lunch time. So it appears that there is some factor involved in the occurrence.

    If the thecar has sat for 8hours the problem occurs, if it has sat for 5 hours it doesn’t.

    This morning I did a little experiment. I started the engine gave it a few seconds to confirm it was playing up turned the engine off and restarted. Upon restarting the problem didn’t reoccur.

    It would be great if anyone else that experiences this problem could also provide some feedback as to when they notice / do t notice the problem. If some logs could be posted would be awesome.

    I’m beginning to wonder if it is a fault in the ecu it’s self.

    Also I have an aftermarket radio installed- cheap android thing - do others that experience the problem have stock radio or aftermarket as well?

  8. #8
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    granville, sydney
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    shot in the dark, do the regular fsi's suffer from the same delaminating valve cover problem? quick video on what i'm talking about: YouTube

    cw.mkv.gtis2

  9. #9
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    Mar 2009
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    Goulburn NSW
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    Thread Starter
    It may be ... but in my case I have disconnected the crank case vent and plugged the manifold.

    I’ve been doing some more tests and if I start the car it runs rough turn it off and restart it runs fine. I have also noticed on my drive into work there is a distinct increase in the reported fuel economy between just starting and letting it run rough and restarting. It really looks like there is some issue with the ecu. I’ve found some tech documentation relating to three ecu I need to sit down and go through. I may not get a solution to this as I’ll need to get the car back to my daughter in the next we or so. She will just have to do the start/restart thing of a mornjng

  10. #10
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    Mar 2009
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    Bit of a development today!!

    I have spent enough time on the Golf and I wanted my SAAB back and my daughter wanted her Golf back so I figured she was just going to have to live with doing a quick restart if it started bad so today was the day to return it to her. (she lives 2 hours away)

    yesterdy I tided up a few loose ends and she didnt have any spare fuses so I randomy populated a few unused slots and left it at that.

    Today I go to head off to meet her and the car started with no fussing about - it should have It has done it every time the car has sat for more than 5 hours for the last 4 weeks..

    I Was running late so didnt have time to look any further into it.
    as I was driving I Was playing around pressing buttons on her android head unit and bought up the vehicle stuff - displays temp, milage, bat voltage and a few other bits and pieces. and I noticed the Battery voltage was sitting at 13.8V +/- 0.1V The interesting thing about this is the whole time I have had the car this has displayed 14.1V and varied a fair bit - I am yet to go back through the logs to check the exact range.

    As i had no diganostic tools with me the best I could do was snap a pic of the fuse box and now Ill sit down and compare the changes. Ive got a before shot then go through the circuit and see what does what.

    At the moment I am thinking along the lines of perhaps the higher Alternator voltage has been casuing issues and perhpas I have added a fuse that is in some way related to the voltage regulation of the Alternator.

    Stay tuned....

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