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View Full Version : Need help now! Boost issue- not a boost leak!



soundspeedstyle
06-05-2010, 10:03 PM
Alright so I have been driving in town for awhile and it has been doing perfect 19lbs every gear everytime.
About 4 miles down the freeway I put the throttle down and my boost is stopped at 10lbs everytime. No cel. About 6 more miles my cel pops on.

Now it has been doing this repeat cylce for a long time now. And in a day or two my boost will come back and about 15miles after my boost returns the cel will go away. Then when I get on the freeway it does it all over again.

I'm selling my car tomorrow and am buying a car the same day I need to at least know what the problem is so I can tell the seller what needs to be fixed. Please help me out! Someone else has had to have this problem before I can't be the only one.

Inval1d
06-05-2010, 10:34 PM
I dont know..... N75 valve?

10kredline
06-05-2010, 10:43 PM
What are you buying?

soundspeedstyle
06-05-2010, 11:06 PM
Alright that's what I was kinda thinking too. I have a mbc that I was thinking about running and see if that fixes it. Any other ideas?

And not that it's important but full stge 3 b5 s4

soundspeedstyle
06-06-2010, 10:03 PM
So I went to o'rieleys today and narrowed their obdll scanner it said "system too lean(bank1)"
that help at all? I know the car spikes really bad but idk why it would lean out on the freeway.

urS6Plus
06-06-2010, 11:35 PM
Check your turbo.

A few guys, myself included, have seen failure in the waste gate flap. It falls off and the turbo wont boost past 10psi. Happened to 2 guys I know, and me this week.

soundspeedstyle
06-07-2010, 07:17 AM
But it will boost 20lbs. All I have to do is let it sit at idle for 15-20 mins or town drive it for ~15 mikes and I got full boost again. And the wastegate actuator wouldn't through a lean code would it? I hope it's just the n75 Friday I'm putting in a new fuel filter (old one might be clogged causing it to lean out) and a new n75.

Hopefully one or the other will fix it! I'll post the result!

In the mean time anywhere else I should be looking? Maf maybe?

Inval1d
06-07-2010, 11:03 AM
So I went to o'rieleys today and narrowed their obdll scanner it said "system too lean(bank1)"
that help at all? I know the car spikes really bad but idk why it would lean out on the freeway.


system too lean bank 1 usually means O2 sensor... edit: Maf problem.. try cleaning it maybe 0_o

Audi Skate Snow
06-07-2010, 12:19 PM
my guess is going to be your MAF dying since it will put you in limp mode

MkFree.B
06-07-2010, 02:32 PM
MAF or MBC. Those things usually dont help....did you try pulling your MBC and seeing if the same results came up? If so, MAF most likely.
Also a possible vacuum leak...but most likely not. That caused the same problem after I fixed my MAF on my car.

walky_talky20
06-07-2010, 03:05 PM
Yep, most common cause for this code is a faulty or dirty MAF.

soundspeedstyle
06-08-2010, 11:37 AM
Alright I'll try cleaning that little guy and see if that helps. The mbc isn't installed yet

soundspeedstyle
06-08-2010, 09:24 PM
Alright so the car went to the dealership today and besides a bunch of oil leaks cracking resivoir bs that isn't true.

They said all the cylinders had fualt/miss firing codes. And the system was running lean.

Idk what the problem is but I'm changingthe maf, o2 sensors, n75 and fuel filter. Othe than that I have no idea. Allthe plugs are new with ~75 miles gapped at .028

nikitynick
06-08-2010, 09:30 PM
check your wastegate lines as well, how thorough of a boost leak test did you do?