Low boost past 4k RPM

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Sep 17, 2007 | 03:33 PM

saturnal

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Low boost past 4k RPM

Really weird problem here. My 2000 A6 2.7T recently started having problems maintaining full boost above 4K RPM. For a few days it was like hitting a brick wall. Afterwards, I could accelerate past 4k, but the boost would be noticeably lower. The car also starts to stutter at 1500RPM, especially when the engine is cold. No SES light. Ran VAG on the car while driving around and wastegate operation was at 95% while running in the high-boost setting for my APR chip. That was the only thing that sounded odd. Up to 4k RPM the car runs perfectly.

I also chacked the hoses for the throttle body boot and all the hoses to the diverter valves. No rips/tears or any loose fittings. Anyone have any ideas????

Alex
2000 A6 2.7TQM

Sep 17, 2007 | 03:41 PM

4Driver4

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Pressure test for boost leaks.

Sep 17, 2007 | 07:56 PM

saturnal

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How could boost leak exactly at 4k RPM, every time? Wouldn't it be variable?

Sep 17, 2007 | 08:54 PM

Mike2kS4

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You just got some good advice, follow it before doing anything else.

Sep 17, 2007 | 08:56 PM

visintainer [vis]

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check your intercooler/hoses

Sep 17, 2007 | 10:16 PM

2fst4u2c

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maybe limping? if there's a boost leak, it'll show up no matter what you're running it at...

check AWE FAQ for a list of "DIY pressure tester" and you'll be straight, but make sure you don't hit it with a air supply that runs pneumatic tools unless you can regulate it down to like 15 psi...

the pneumatic air is normally like 100 psi, I don't think that'll help at all.

If you hear a leak, fix it, re-test and then test drive.

If that doesn't work, then you know you can rule out boost leaks...

Sep 18, 2007 | 06:00 AM

haggard69er

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check tbb and vac line. had the same problem.

tbb was torn. could hold 15psi up to 4k, past = the brick wall as you said. also right after i fixed torn tbb, my vac line blew up(the braided one). when i popped my hood it looked like a birds nest next to my y pipe. i also have the same symtomes with the blown vac line and a semi popped off ic hose.