Hi guys,

I seriously need your help with this one as it has me baffled and confused. Let me start at the beginning:
5 weeks ago I started replacing my timing belt (with the full kit) since my water pump was leaking. At that time I figured it would be a great idea to replace all the gaskets to keep the car running for a long time. So I pulled the heads, replaced the head , intake + exhaust manifold and valve cover gaskets. During this process I cleaned everything and even fixed the stuck manifold flaps. It took me 3 long weekends (with some help of a good friend) but the car came back together. We had to jump start the car since the battery died during this process. Car started up and ran fine.

Flash forward to last weekend - I filled my gas tank with v-power and added some Techron fuel injection cleaner (to clean off anything I might have loosened up during my cleaning process - bad idea?). I started the car up a day later and smelled gas - found the fuel supply line leaking gas. I let the car sit and bought a replacement line from Audi - which I installed 1 day later. Car would again not start and had to be jump started. By then I knew I needed a new battery (it did last 6.5 years, so not that bad). Anyhow the car barely started and started misfiring (multiple random misfires). I figured it was the combination of the car running off the alternator since battery was pretty much dead and the fact that the fuel line wasn't fully pressurized yet. after some revving up to 4k the car seemed to do fine - drove to Pep-boys and had a new Bosch battery installed.

Now the car starts up quickly but the idling is horrible when cold! It revs up and down between 900 and 1100 rpm during cold start and shakes the entire car - however no new codes are being thrown (no soft codes, no misfiring, etc - checked with VAGCOM). I also did the TBA without success (also with VAGCOM). On top of that today my power brakes were also gone until the engine warmed up. Once I reached the first bar on the temp gauge the revving issue at idle and the power brakes were fine.

I can't explain this and the car drives just fine (power is there from low to high rpm range, no codes and no misfires). I would gladly appreciate any help you might be able to offer.

 

It sounds like a vacuum issue. I would trace the vacuum lines one more time.

 

I did check the vacuum lines three times already even with the vacuum line diagram for my car. All the hoses are attached correctly and have been replaced with new lines.
So let's say this would be vacuum related, why would it only affect me when it's cold and why would it do something to my brakes (or is that just coincidence)?

edit:
I did some googling and found out that the brake vacuum uses the vacuum from the engine, so you could be on the right track... I will check very thoroughly again tomorrow morning! Thanks.

 

I think I found the "sucker"

 

Ah, the suction jet..

ECS tuning

 

Already ordered it and with shipping still half the price of what Audi charges (29$ with shipping included vs. 65$ from Audi) - fcpgroton
I hope they don't sell stuff that will break shortly after installing it .. but it can't be much worse then what I have right now.

btw:
When I called Audi they stated that the original part number was indeed 058133753B however it has been superseded by 058133753D. Not sure if that is why ECS is selling that one so dirt cheap.

 

Supposedly the original suction jet was prone to getting clogged. The updated version took care of it. ECS sells many different vendor products, and the MTC version is the cheapest. I consider myself an "edumacated" cheapskate. As an example, timing belt related product... I would order a brand name/OEM. A suction jet? Can't really say that busted suction jet pump will cause any damage to the car nor is the design of the suction jet so complicated that you need a reputable vendor... So I stick with the cheap stuff.