(I posted this in the tech section, but figured since its a B5 I should repost here too)

99.5 a4 1.8t. I've had to replace a lot, but things are getting better. I just replaced my ABS mod with one I got in the Junkyard for $25 (dif model # but fit), the ABS light is still on but at least the "brake" light isn't flashing anymore. I have a PC-16 file and the car feels like its running good, no more stuttering or dying at 4500 rpms but is still only boosting at 9psi when it should be at least 18psi. My check engine light is giving me a code P1565, I replaced the throttle body and put in a new ECU cleared the codes with OBDII and I'm still getting the same P1565 code. So now the old ECU with PC-16 flash is back in. I DON'T have Vag-com, someone mentioned a TB alignment? I took it to a shop for $50 to have a guy plug in his Vag-com but he said it wouldn't communicate with it, not sure if he knew to do the alignment or not.

Long story short... car runs good, boosting at half (limp mode?), P1565 code (idle problem), I'm guessing the Idle problem is why I'm only boosting at 9psi.. Just looking for Ideas on what to do next. Anyone in south jersey area with a Vag-com I could swing by?

 

p16 is hammer for a k04 right?

so you have a k04?

9 psi is not limp, 5 psi is.....

idle problems are probably a bad vac issue somewhere...

 

I heard with a chip when the car goes into a limp mode it'll only boost half of what it should.. I don't have any crazy psi spikes or anything tho, I thought with vac leaks you'll have spikes? Yea k04

 

So I just took it back out again.. It looked like I was around 6psi in first gear, and 7-9 in second and third.. maybe this is a boost leak?

 

PC-16 is the K04 file for DBC.

If you were hitting limp mode your max boost would be whatever pressure the wastegate spring is set at.

You can build a boost leak tester from hardware store components (I got them from Lowes). It's a very useful tool, just like VAG-COM... Don't know why you're having communication issues though.

 

Ok so I found a leak in the line going from n75 to the turbo. Replaced the line and continued the boost leak test. My car is now boosting at 6psi in all gears, but my main Intercooler line keeps popping off from the turbo to the intercooler at 7psi.. Do I need better clamps or something?

 

Which intercooler do you have? I've popped plenty of IC hoses off. You really NEED T-bolt clamps that are cranked down on to prevent boost leaks. I had to find out the hard way.