2.0 FSI Poor idle when cold

[MEL744]

Yep was thinking it would show up under load - didn't think it would be related to this issue, more of something I have been curious about for a long time. If the follower wears through completely (from research) you would tend to get check engine lights related to low fuel pressure and metal fragments throughout the top of the engine. As for what causes it no one is entirely sure, could be improper hardness of the camshaft or follower from a certain batch - it may not even affect these oddball engines. I guess next time I have the intake manifold off might check it out for peace of mind.

[saabman]

Checking it wont hurt. I went through some logs today at lunch time and found some logs of fuel pressure and form what I could see I dont think I have an issue wiyth the pump the actual pressure follows the specified pressure beautifully, I figgured if there was an issue the pressure would be down but now typing about it I wonder if the pressure regulator is able to compensate for for the wear to a point ???

closed loop systems keep you guessing.

In looking at the logs I had a few good warm starts and cold bad starts and it was interesting to note that on a warm start the engine rpm increases straight to 1200rpm or so then drops straight back down to around 800. this occurs before any valid readings are coming from the O2 sensors.
on a bad start the rpm rises to 1200 and sits there until the o2 sensors start giving some feedback than 10 seconds later the idle drops to 800rpm.

its like the parameters for open loop operation are good for warm start but waaayyy out for cold start and once it goes to closed loop mode it compensates and brings it all back into line.

If we could get our hands on the med9.5 Funktionsrahmen even in German I think would help towards understanding the cold start/open loop parameters.

[saabman]

I came accross this document http://contiman.free.fr/reprog/repro...eur%201.8t.pdf its specifically about the MED7 but has lots of info about the maps and im hoping there is enough similarities between the 7 and 9.5 to make some sense of whats happening.

Its pretty full on so will take some time for me to digest it..

[saabman]

Yep was thinking it would show up under load - didn't think it would be related to this issue, more of something I have been curious about for a long time. If the follower wears through completely (from research) you would tend to get check engine lights related to low fuel pressure and metal fragments throughout the top of the engine. As for what causes it no one is entirely sure, could be improper hardness of the camshaft or follower from a certain batch - it may not even affect these oddball engines. I guess next time I have the intake manifold off might check it out for peace of mind.

my guess would be improper hardening of the follower.

[MEL744]

I agree we definitely need to understand how the ECU is making its decisions. Made a quick log today of the operation of the O2 sensor heater and resistance. The first set are cold, the second set are from a 'hot' normal start. Surprisingly, the B1S1 heater is not activated until about 20 seconds after cold start, and the resistance stays at 510 ohms until 10 seconds after the heaters are activated, when it begins to fall. After it stabilises around 300 ohms the car begins to idle normally. I thought the resistance was supposed to be much lower (around 10 ohms?). None of the post cat sensor heaters appear to be activated, but they do momentarily come on at random points during the normal idle after hot start. I am beginning to think the idle idle warming is activated when the difference between the air temp and coolant temp is below a certain threshold but it doesn't explain why if you restart the car the problem goes away. There is also this value called temperature adaption factor 1, 2 and 3 on measuring block 104. On a cold start all 3 values are set to 28.9%, haven't logged it on a warm start. Any idea on what this is? Was thinking maybe something to do with air temp but could also be calculated some other way.

[saabman]

I had a bit of a look around last night for info on that adaption factor - no idea...

The heater resistance Im assuming thats MB41 :1 from the label file it says "Range: 0.0...500.0 Ohms"

so anything could be right

I agree that it seems to be the idle warm up for the cats is activated the rich mixture and extreme retarded timing from what I understand is what it should be doing but why??

I remeber reading somewhere with some of the diesels if the starter doesnt turn the engine fast enough the car wont start and the fix is to replace the starter. but the reason it doesnt start though is the fuel map below something like 200rpm is for no fuel - so of course the engine wont start, so another fix is to change the map so it delivers fuel at a lower rpm.

something i often experienced working on my air cooled VWs was a symptom wasn't necessarily caused by a single fault but a number of things which on their own wouldn't be a major problem, the compounded effect was enough to push it over the edge and bring you to a stand still.

when I started looking at Nats car I found one spark plug so loose I didnt think I had the right pliug spanner i undid it with my fingers and the plugs were the wrong ones, the purge valve was stuck open, the MAP sensor was full of oil and the PCV pipe between the rocker cover and manifold was so stiff it leaked at nearly every joint. rectiying all those things has made NO noticeable change.

ive got a copy of a ecu file you can open in winOLS if you want to try you hand at finding maps

[saabman]

Ive been doing some hunting around the web and purusing various forums and the general consensus for the cause of this issue is the build up on the intake manifold but NO one that I have found yet has quantified the statements. it usually goes my car idles bad the responses are sounds like the N80 valve, have you replaced your coil packs, made an offering of a virgin leopard goat to lucas or cleaned the valves. thats usually where the threads stop.

No one has come back and and said cleaning the valves fixed it. And no one has really said why its a problem. there has been a few possibilities like a bit of crud holding the valve open or the build up effecting the smooth flow of air into the cylinder - but these dont account for the only happens when its cold and the goes away if the engine is turned of and back on again straight away.

The valve build up I could see causing a reduction in performance but screwing the idle like we are seeing, im not convinced.
here is an interesting paper on the cause of the build up Formation of intake valve deposits in gasoline direct injection engines. - Free Online Library

[saabman]

1.4TFSI data

I got a chance to grab a log from the 1.4tfsi at work on friday, been a 2017/18 model its quiet a different beast so I think of little use. I only could get it for 10 minutes so I just grabbed what I could Dropbox - LOG-01-IDE00021_&11.CSV - Simplify your life

[MEL744]

That connection you have made to the TDI hot start issue is quite interesting and worth looking into further. I'm wonder if, given the age of the cars now, that a combination of factors are sufficient enough to throw the startup parameters outside their assumed values when the car was new. If you could send the ecu file that would be great. Also , from what I can tell, the car has not been serviced at the dealer since the 3 year warranty expired, I think I will get in touch with a friend who works at a dealer and see if he can check for any service bulletins or ECU updates (have seen this fixing similar issues on Audis).

It's quite remarkable how changing all of those things made no difference. Regarding the PCV system, I believe it is functioning correctly, but haven't tested it fully. I tried removing the oil cap and the idle became very lumpy - which apparently indicates that it is working. It is common for the PCV valve to go bad on the turbo cars, and the fix there is to buy a new valve assembly which is not too expensive. On these engines though, the valve is integrated into the rocker cover - not cheap to replace. I did find where you can buy the membrane only for a reasonable price. Membrane for valve cover VAG 06F103469D 2.0 FSI - Vanos BMW Repair kits for cars This involves prying the circular cap off, and at the moment I'm not game enough to try it, given it is obviously not designed to be serviced. Might give it a go at the wreckers and see what condition the valve is in on the car there.

The other threads on this issue are frustratingly incomplete, and I too am not convinced that carbon build up on the intake valves is to blame (or at least the sole cause). Surely if the carbon was causing enough disruption to airflow to cause misfires on idle, the problem would be evident or even exacerbated by different, more strenuous operating conditions. I cannot say I've noticed any of these, the car seems to pull well and without hesitation at wide open throttle throughout the rev range. That said, one day I will probably clean them as well as the the manifold and check the HPFP all in one go (and with the right set of hose clamp pliers this time). The data from the 1.4 TSI Caddy seems quite different and I can't say I'm too familiar with that engine. Seems like it is using a narrowband sensor for B1S1. The resistance is much lower than any of the wide or narrowband sensors on my engine.

[saabman]

Thanks for the link for the replacement diaphragm I pulled the cover off the pcv housing to have a look - it comes of quiet easy i just levered it off with a screw driver and it just pushes back on. if the diaphragm isnt obviously torn it should be good - I pulled mine out and tore it in the process it is incredibly thin.

You could probably check the operation of it by pulling the cover off and starting the engine. the manifold vacuum should pull it down. the idea of it is to limit the amount of vacuum in the crank case so you dont suck air and dirt in through the seals.

there is two ports under the diaphragm, one goes to the engine and the the other to the manifold. As the vacuum increases it pulls the diaphragm in against a spring until a seal on the bottom of the diaphragm closes of the port going to the manifold. The residual vacuum in the crankcase holds the diaphragm down until leakage/blowby reduces the vacuum and the diaphragm lifts opening up the manifold port again which sucks the gases out of the crankcase etc.

when I had the manifold off i struggled with putting those clamps on with a pair of angled needle nose pliers. I must have not been very happy with the progress as my 3 year old who had been "helping" disapeared and a short while later my wife turns up asking if i needed some help

My heaters read 510ohms - more investigation required on that one.

I dont think Nats has been near a dealer probably for the same amount of time either...
She is talking about coming down in a few weeks so I will do a leak down test then and see if it shows anything useful.

Ill try and post the ecu files tomorrow -