2.0 FSI Poor idle when cold

[MEL744]

Do you know how to conduct the lambda aging tests? Haven't found anything that detailed on how to start them - have a day off tomorrow so might try and work that out. Will make a plot of all the lambda values and fuel trim values tomorrow too. If you could get your hands on one of those TFSI Caddys that would be great. Even though the sensor set up is not exactly the same it will give us a good benchmark for how sensors should react and values change with time.

[saabman]

couldnt get my hands on the TFSi caddy today but hopefully one day next week

have you got logs of Groups 32, 33 and 36 at idle?

I was looking at your graphs to day and it seems that

[saabman]

Not really sure about the aging tests. I believe you select the the appropriate mb and click the basic settings button then something like press the brake and accelerator.

[saabman]

Hmm I shouldnt post from my phone late at night

If you are able to get some logs maybe 32 33 and 36 at idle for about 30 seconds (after the engine has warmed up) and around 2000rpm for about 30 seconds.

It seems to take about 10seconds for the long term fuel adaption to change im hoping by doing at a fixed load just varying the rpm will reduce the noise from accelration etc.

Have you done a compression or leak down test?

I keep reading about the dirty intake as a posibility and from what I can gather it seesm to be caused by crud preventing the valves from closeing - if thats the case a leak down test will show a leaking valve - I didnt think to do it when I had nats car here

[MEL744]

Managed to get the data for 32, 33 and 36 at idle and holding the rpms relatively constantly at 2000rpm on a warm engine. Also worked out the aging test (you go to basic settings select lambda aging, press the on button then hold the brake and accelerator simultaneously until it completes) - this came back as B1S1 OK. I also went in to generic mode and had a look at the current through the B1S1 sensor as well as some other values when driving around (35 mins) you can view that here (includes cold start). Looks like long term fuel trim stays constant for both tests. Haven't conducted a leak down or compression test since I don't have the tools for it.

2000 rpm plots

Idle plots

[saabman]

I dont have access to the idle plots but the 2000 rpm plots are fine

The 2000 rpm plots look good the constant 7% partial throttle trim while the idle is only around .5% is interesting it seems tio indicate leaning out as the throttle opens maybe a that from what i've read points to MAF issues but I believe we only have a MAP sensor mine was mounted rather low on the manifold and full of oil. I cleaned mine out with brake/parts cleaner. only one torx screw holds it in but there is not much room between it and the radiator, just fiddly not impossible. I seem to recall pulling something else off to make it a bit easier to get to. Cleaning it didnt help the engine running at all. I didnt have any before and after logs -haveing said that maybe I do, Ill have to dig a bit deeper.

I bought a cheap leak down tester of ebay - it is very dodgey and doenst really work properly. basically it hooks up to an air compressor and pumps air into through the sparkplug hole and gives you a measurement of air leaking out of the cylinder. The advantage over a compression test is you can pinpoint where you are loosing compression. If you have a way to pump air in to your cylinders you can do it as well. The idea is you pump air in and listen to the oil filler (remove the cap first) intake manifold and exhaust. if you can hear air escaping through the intake it means you have an intake valve not closing through the oil filler you have leaky rings (a bit going past the rings is normal)

The kit just gives some guages and regulator so you can determine the amount of leakage so you can compare cylinders. the cheap one dosent work properly so that bit doesnt work but its great for getting regulated air into the cylinder and have a listen. I didnt even give it a thought to put it on nats car when I had it here i used to use it a fair bit when i had a couple of air cooled vws on the road, thats a whole another story...

I did some scans on the wifes Amarok and been a diesel i couldnt see anything worth logging. I ll have another go at TFSi at work tomorrow.

[MEL744]

Changed the sharing for the idle plots, so you should be able to access those now. Regarding the MAF sensor, I could be misunderstanding your description of the MAP sensor location, but here's a photo of the intake pipe I got from the wreckers. It seems to be a typical location for a MAF sensor?

From that it sounds like a leakdown test would definitely be worthwhile, will you be able to try the test any time soon? Otherwise I might buy one, but probably won't have time to try it out for a while.

[saabman]

No that looks like intake air temp sensor 1 location.

I’ve just been looking in the elsawin for a location of theMAP sensor but there is no images for it. It’s G71. From memory it was on the intake manifold below the throttle body.

I’ll try and get Nat to do a day trip and visit her dad if she can do that I’ll put the tester on it.

[MEL744]

Yep just been on the parts website and found that sensor is air temp. Also found the location of G71. Number 13 on this diagram - listed as: 13 - Intake manifold pressure sender -G71- with intake air temperature sender -G42-. Furthermore, found out the design of the HPFP is very similar to that of the troublesome GTI one... definitely something to keep in mind for maintenance. Diagrams of that here.

[saabman]

Yep that’s the sensor - because it sits so low in the manifold it’s a good candidate for filling up with oil deposited from the crank case ventilation.

I wonder how we could test for the potential of a dodgey fuel pump - low pressure under load perhaps?