A messed up maf will give all the problems the OP had except for the 2ndary air flow fault. Thats either a bad air pump, leak in the pumps plumbing, or bad combi valve. I wouldnt worry much about that one.

As for the DV vac line, on 00+ they don't hook right up to the intake mani like AEB engines. When I did mine on my 00, I taped the hose onto a wire hanger and fed it through under the intake mani in order to slide it onto the nipple. Another way to do it is gut out a pen, feed the vac line through it, and use the pen to guide it through under the intake mani. If I remember correctly, it might be easiest to remove the coolant tank and get at it from that angle.

 

i removed the coolant tank and got the line on the nipple under the manifold, but i was unable to get a hose clamp in there. how necessary is a hose clamp here? oh and its on an 01 1.8T

 

Dont worry about the hose clamp. You really don't need them for vac lines as long as it's a snug fit. I normally just use zip ties for them.

 

the only problem is that i keep getting a system lean code and after clearing the codes the engine stumbles on the next startup and i get a missfire.

 

You sure it's a misfire? Is your CEL flashing and do you have misfire codes? Post up the specific codes. 9 times out of 10 a lean code refers to a bad maf. You'd have to have a huge vac leak to get a lean code, and your idle would be way eratic.

 

it stumbled and flashed the CEL and the first time i got missfire codes on the VAG-COM. Ill run it when i get out of class and post up what i get.

Ran VAG COM and im getting multiple missfires with missfire on cylinders one and two. cleared it, got another rough idle, and a cylinder 1 missfire. cleared it again and things seemed to be running smooth. i havent driven it anywhere yet though.

 

try switching coil packs 1+2 with packs 3+4 (remember which cylinder you are switching them from/to) if the problem follows the coil pack to the new cyl, its the pack itself. if it stays in the same cylinder. its the ICM. also might as well go get some new spark plugs while you have your coil packs off.

 

i already switched the coil packs and got the same stutter this morning. Spark plugs were just changed two months ago when this problem first started. its all the same symptoms/codes as a post that just went up so i'll leave this one be..

 

I replaced all the vac lines, which fixed my instant mpg reading on the driver display, but both codes remain- btw it's easier to replace when you unhook the air intake tube from the engine, and the coolant reservoir has been loosened so you can move it around. It allows you to get a free hand under all that stuff on top. (also good for oil filters)

The problems persisted since my first posts, and now the engine is beginning to start up with more and more noises. I don't suspect turbo problems anymore, just from what I've read since. I'm going to try to replace the combination valve and double check my vac lines.

Whatever it was the car has been able to run while the problem has persisted.

 

All my vacuum lines are good; I just checked them. I was going to go about checking the control valve. I also heard some people suggest the MAF. Is that possibly the problem?