Engine hunting 2.0tfsi

[Turbo jay]

Hi guys

Right noticed when I pulled up the drive after work engine was idling then started hunting,
do you think this could be a faulty pcv valve?. Also Getting fault code P0171 (system too lean blank 1)
Which I've done a search and is suggesting it could be anything from a vacuum leak,lambda sensor, or maf.
anyone had the same/similar problem? Any help appreciated.

 

[Flexiblemouse]

Sounds like a vacuum leak, unmetered air is getting in and causing the car to run lean, screwing up the MAF readings too. You need to connect a phone or tool to the ECU (assuming you have no vac/boost gauge) so you can monitor the vacuum for big fluctuations, I use an android app called torque pro.

 

[Turbo jay]

Sounds like a vacuum leak, unmetered air is getting in and causing the car to run lean, screwing up the MAF readings too. You need to connect a phone or tool to the ECU (assuming you have no vac/boost gauge) so you can monitor the vacuum for big fluctuations, I use an android app called torque pro.

Hi mate I've got the dash command app for the iPhone that's what I got the fault code from, it was late when it started to happen so ill plug it in tomorrow and do some logging on the way to work., Then check all Hoses, if it is a potential vacuum leak where is it likely to be leaking from to cause these issues?

 

[Flexiblemouse]

I would monitor the vacuum at idle for a few minutes, it should sit around 23 in/hg or so once warmed up. With a vacuum leak it will fluctuate a lot and run rough. Leave it running and check all the vacuum hoses are seated correctly, that they have clamps on and do not appear damaged. Make sure the dipstick and oil cap are on properly while you are there. Hopefully you will find something obvious, if not then it may be time to replace the hoses 1 by 1.

 

[Turbo jay]

Thread update:

Decided to change pcv after seeing no visual leaks and job done, all sorted so turns out it was a faulty pcv. took 10mins to change piece of cake.