so the past 2 times I've driven on the interstate for a hour or more, the car has gone into limp mode, no cel or anything, just won't boost more than 4lbs... usually goes back to normal when I cut the car off and let it sit for awhile.

I'm not really good with vagcom, but I tried to scan it and nothing came up... its very annoying, I don't know whats wrong

 

That sucks dude!

 

my guess is some sensor is throwing weird readings at the ecu.. maybe IAT sensor?!

 

I wonder if you can clean that sensor, or if it would just have to be replaced...[>:]

 

you can clean it.. takes all of 5 mins.

I pulled mine out and cleaned it with electronic/maf cleaner.

it gets greasey.

 

i had the same problem, check egt, maf reading and requested boost vs actual boost, one of those 3 will let you know right away what happening when you hit limp.

my issues with limp was a faulty EGT sensor that was giving wack readings and when boosting higher than 17 psi (k03) i would hit limp when it skiped into overboost.

 

wierd problem, anymore symptoms you can give?

 

none, it comes out of nowhere. and only does it after i've been driving a hour or more on the highway.

 

Boost/exhaust leak? What's that valve that collapses on the 225's? Forgot the name of it....
I'm sure (like anything else with our wonderful cars) if it continues you will eventually throw a code.

 

I beleive you are thinking of the Turbo inlet pipe, but his issue is with a bad sensor reading.

as i stated i had the same problem and it was happening in the same manner, when you on highway cruising then u are in vacuum, when car goes into boost it climbs way to fast for the n75/mbc to keep up and then throws you into limp.

it may help to go to tex get the blocks for EGT, MAF and Requested boost vs Actual boost. and log that on your VAG just log and drive, i would also suggest that today while you drive keep an eye on your boost guage and see the relationship between boost generated to get you into limp.

otherwise, take it to a shop for a pressure leak test.