Running rough when cold.

[Max]

Hello there!

Well I’m new on the forum but I’ve watched Eric for years now. I walked into a problem for a while now, I’ve got a Audi A4 B5 2.5 TDI and when it’s cold it runs rough it won’t stall but it runs rough, after around 1 to 2 minutes it runs smooth again and it stays like that. But what can it cause to run for a min or 2 so rough? :unsure:

Here I made a video, it could be worse at lower temps. “I stepped on the gas a few times” and you see it smoothed out. :huh:
https://www.youtube.com/watch?v=dynULXsKsXc

Timing off?
Maf sensor?
Cam sensor?
Engine will explode upcoming weeks or the world will end maybe because of this? :whistle:
I don’t know what it could be.

Thanks

-Max

Topic

[Daniel Weith]

Have you inspected the throttle body condition; it may need to be cleaned along with the MAF and the IAC.

Also, has any regular maintenance been completed lately, if so please list.

[Max]

Hi Dan,

Well I do always replace every 10.000KM the oil with 5W40 and filter, it always have used this oil in it’s life time. The timing belt have been replaced but it did it before to. New CV joints. New upper engine thermostat it also did it before and after this. New filters. And some stuff around the car like wheels and headlights but that shouldn’t cause the problem.

It got 197.000KM in the clock or 122,410 miles. It’s a 6 speed manual. The camshaft have been checked and it was stated “okay” but I will maybe replace it when the timing belt needs to be done again.

-Max

[Daniel Weith]

I would suggest taking a look at the throttle body it may need to be cleaned along with the MAF sensor and IAC.

It is also possible there is a vacuum leak due to rubber/plastic cracking and or a line detreating over time or perhaps come off.

Most use an unlit propane torch to find the leak, be sure to have a fire extinguisher handy if you use brake cleaner or other flammable spray.

Eric has a video on the procedure to diagnose a vacuum leak – http://www.ericthecarguy.com/faq/finding-and-fixing-the-causes-of-poor-mpg?start=5#VacuumLeaks

[Max]

Thanks Dan, I will get a look in to it asap! As for now it seems it’s not like the engine is going to have a breakdown soon, I hope.. :whistle:

[subhobroto]

Did you get a chance to inspect (and possibly clean) the butterfly valve? If you have not, I have been meaning to write a quick HOWTO for electronic throttle bodies that have a DC motor with encoders and can carry out idle sweeps even with the engine off.

Please let me know 🙂

[Author]

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