2.0 FSI Poor idle when cold

[MEL744]

Just had something incredibly strange happen. Got in the car, started it up and it idled at 1200 as normal but it was smooth! My brother even noticed it. Seemed to run for a bit longer than usual (at a guess 60 seconds). This seems like how the car should be operating. The only parameters that I can think of as being slightly different are that the car has sat for 48 hours and the fuel level is very low (in the red dashes). Also its very cold in Melbourne at the moment but the car gets garaged so thats probably not related. Was going to make some logs but was in a rush so decided not to.

[MEL744]

About the PCV diaphragm, thanks for the heads up on that one, will be careful not to tear it. The struggle with angled needle nose pliers sounds very familiar... When you say 510 ohms on the heaters, is that constant and for all heaters? Also, tonight on the way home from uni I started it (with low fuel still) and sure enough it idled smooth and for longer at 1200rpm. Only put a bit of petrol in tonight so by the end of the week it will be low again and I can make some logs. Any suggestions for what might be useful to check?

[saabman]

ECU files good luck making any sense of it its for a TFSI but still a 9.5.1 so "should" be relevant" Dropbox - Bosch MED9.5 - Simplify your life
I think I found it on ecuedit.com ?

Im at a bit of a loss as to where to go as well - I had a similar experience - the day I took the car back to my daughter - it started and idled fine interestingly it was low on fuel as well I didnt have the laptop with me and was running late so couldnt check anything - but the android head unit she put in can display some very basic data and the only thing I noticed was the voltage was almost exactly 12V after the car had started normaly it is around 14V. I was wanting to investigate the battery/charging voltage a bit more but that was my last day with the car. Maybe have a look at battery voltage.

I had read about about possible issues with a full tank of fuel and issues with the purge valve - I had discounted that as I had removed the purge valve and blocked the port in the manifold, Ive since replaced the purge valve and no noticable differnce.

[saabman]

As for the Resistance thats for B1S1 and B2S1. The field for B1S2 and B2S2 is blank (MB41 and 42)
510 is out of range acording to the label file Ill need to look into this further
Data:
41 510 ohms Resistance Htg. S1 OFF .......... Htg. S2 OFF
42 510 ohms Resistance Htg. S1 OFF .......... Htg. S2 OFF

Description:

41 0 Lambda Control (Lambda Sensor Heating Bank 1)
41 1 Resistance Bank 1 Sensor 1 Range: 0.0...500.0 Ohms
41 2 Heater Condition Bank 1 Sensor 1 Range: Htg. S1 OFF/Htg. S1 ON
41 3 Resistance Bank 1 Sensor 2 Range: 0.0...0.5 kOhms
41 4 Heater Condition Bank 1 Sensor 2 Range: Htg. S2 OFF/Htg. S2 ON

42 0 Lambda Control (Lambda Sensor Heating Bank 2)
42 1 Resistance Bank 2 Sensor 1 Range: 0.0...500.0 Ohms
42 2 Heater Condition Bank 1 Sensor 1 Range: Htg. S1 OFF/Htg. S1 ON
42 3 Resistance Bank 2 Sensor 2 Range: 0.0...0.5 kOhms
42 4 Heater Condition Bank 1 Sensor 2 Range: Htg. S2 OFF/Htg. S2 ON

[MEL744]

Interesting, so your two sensor 1s are behaving the same as my single sensor 1... Will give the ECU files a go later this week hopefully. You might be onto something there with the voltage, it seemed to take a little longer to start today, but not sure - definitely going to be making some logs of that.

[saabman]

been trying to find out more about the Lambda sensor heater resistances but nothing yet BUT i did come accross a SSP which is specifically for med9.5.1 Dropbox - SSP_322.pdf - Simplify your life

[saabman]

Just been persuing through elsawin (runs heaps better in XP) and come across this Technical product information
Dropbox - VW TPI cold start idle 1200.pdf - Simplify your life

Customer statement / workshop findings
After a cold start the engine runs sporadically for about 80 seconds at an idle speed of 1200 rpm.
Technical background
The idle speed is raised to about 1200 rpm.
Production change
---
Measure
The measured value block 56 of the engine control unit shows the actual value (field 1) and the specified
value (field 2) of the idle speed.
If the engine temperature is in the specified range and the two values in measured value block 56 are
identical the engine has no complaint.

[MEL744]

I also found that SSP the other day, doesn't look like it has anything related to this issue, but still very handy to have. Today I checked the values and they match but when its running rough there is a fair bit of fluctuation (+/- 60 rpm) around 1200 rpm as you would expect. Interesting that specifies 80 seconds which is how long it goes for when the fuel is low, but when its rough the high idle is less than 40 seconds.

[saabman]

That is rather interesting - have you checked the operation of your purge valve? It’s the only thing I can think of that would have any impact dependent on the fuel level. I’m guessing with a higher fuel level there would be more vapor passing through and saturating the carbon filter and thereby creating a higher fuel load if the purge valve was either open or stuck open.

I know mine was stuck open - i could blow through it with ease and pulling it apart I could see bits of carbon holding it open. While I was waiting for a new valve to arrive I blocked the pipe to the manifold which would have eliminated any potential effect of fuel level.

[saabman]

been contemplating the technical bulletin some more and noticed it doesnt mention the specified temperature range which has me wondering which sensor is responsible for enabling that mode and why it was occurring all through summer - of a morning the engine was around 17 deg and the oil/intake/water temps were all arround this value and of an afternoon it usually around 28-30 deg not exactly what you would could call cold temps - id love to be able to understand the opperation of the ECU better and the maps involved at engine start..
MB 130-135 are all temperature related might be worth having a look there. interestingly though I noticed inlet manifold temp can be viewed but not the temp sensor on the air filter box.