boost leak?

[ryan]

I just finished my vdo boost gauge install. Tapped into vacuum lines that runs into fuel pressure regulator. I hit 18lbs of boost at wot, than it doesn't hold. Slowly drops off. This Normal? I know in my S4 it holds boost steady until I let of the gas. What are the typical places it would leave from?

[Elevens]

I know mine tapers off from around 15-16 psi Max to around 10psi under WOT. My Tuner prefers good fueling and timing over high boost for Max performance. And by the way Welcome to the Forum whoever you are......................

[JSRS6]

Well, if I had to guess...I'd say your diverted valves. The stock ones are only designed to hold about that much in their prime. Besides that, a tune might, MIGHT, hit that.

[ryan]

I know I have stock diverter valves, so I am going to get done new ones.

By the way i'm Ryan from Washington state. I have a 03 RS6. Owned it for about 2 years now. It's chipped, although i'm not sure what tune I have. Also have Milltek exhaust and a few other minor things.

[ryan]

So I just did a quick scan after boost gauge install and I am throwing p0171 and p0174 too lean on each bank. Did done research, vacuum line leak will cause this. Maybe I have to redo my boost line?

[ttboost]

You could have a problem, but it is absolutely normal for your boost to taper off fairly quickly...tiny little turbos and run out of steam pretty quick...

[lswing]

1-find out the tune, i had to resort to receipts. 2-you can hit 18-20 with these ko4's, but they drop quick after that. Back off the boost so you dont get that big tq hit down low that feels cool, but busts up your tc and trans. Since i backed down to 16-17 max it's golden till 4,800 then drops off smooth. Close to perfect for what the turbo wants.

Update your sig for location, folks up there can check your car, if you're in town we can see if you have Revo, kinda siunds like it...

3-what ttboost said...

Edit; Revo and/or too much boost will run lean, don't ask...

[TOAvusRS6]

Your codes may be related to the airbox not being seated properly. If there is any gap at all between the MAF and the seals then I believe these codes can be thrown. Search the archives to be sure. I'll look for you as well if I can.

[ryan]

Yeah, i figured that out when i re-ran my boost line, that air box is a real pain in ass to get back in, any pointers? the air box is still sticking out 2-3 mm.

[DHall1]

Plus 1000% to #1 below.

You better get a Vagcom and start doing some data logs of 3,31,115 before you pass go. Save your money on DV for now. That is high boost if your not getting enough fuel it could be dangerous.

You really need to know specified boost/actual boost and specified 02 voltage and actual.

.02c


1-find out the tune, i had to resort to receipts. 2-you can hit 18-20 with these ko4's, but they drop quick after that. Back off the boost so you dont get that big tq hit down low that feels cool, but busts up your tc and trans. Since i backed down to 16-17 max it's golden till 4,800 then drops off smooth. Close to perfect for what the turbo wants.

Update your sig for location, folks up there can check your car, if you're in town we can see if you have Revo, kinda siunds like it...

3-what ttboost said...

Edit; Revo and/or too much boost will run lean, don't ask...

[ttboost]

Yeah, i figured that out when i re-ran my boost line, that air box is a real pain in ass to get back in, any pointers? the air box is still sticking out 2-3 mm.

What I did, and I don't necessarily recommend it, but it works for me...I unscrewed my MAF's from my airbox, wrapped a turn or 2 of black electrical tape around the base, where they seat in the plenum, and put them back in the plenum. I then just seat the airbox over them. I MAY leak a smidge (I don't think it does) between the airbox and MAF's, but that won't throw a CEL or any codes. And it now takes 15 seconds to get the airbox on and off. My car runs awesome and I don't get the annoying codes AND I will never spend $50 on stupid O-rings for the plenum...

[ttboost]

[QUOTE=lswing;246621]Back off the boost so you dont get that big tq hit down low that feels cool, but busts up your tc and trans.

I find that I can keep it at 20psi now for that cool hit...and it doesn't really seem to bother my TC anymore...stupid paddles still don't work though...

[Bigglezworth]

What I did, and I don't necessarily recommend it, but it works for me...I unscrewed my MAF's from my airbox, wrapped a turn or 2 of black electrical tape around the base, where they seat in the plenum, and put them back in the plenum. I then just seat the airbox over them. I MAY leak a smidge (I don't think it does) between the airbox and MAF's, but that won't throw a CEL or any codes. And it now takes 15 seconds to get the airbox on and off. My car runs awesome and I don't get the annoying codes AND I will never spend $50 on stupid O-rings for the plenum...
This is exactly what I do also. In fact I don't even have the metal clips on the flex connectors leading from the front ducts as I don't care if there are any small leaks in the air cleaner assembly itself. When doing a number of tests and working on odds and sods on the car, I can easily run it without the airbox assembly then.

[ttboost]

Great minds think alike, huh Tim? How you been?

[ryan]

So after spending three hours last night trying to get it so seat right, i did some measurements and it was seating just fine, but loose. I think those seals need to get replaced. So i went to autozone and took ttboost's advice and got some self sealing tape. Two wraps around each MAF, it fit perfectly. put everything back together and cleared the codes and went for a drive. Codes didn't pop again and holds 18lbs of boost no problem. Thanks for the help guys.

[lswing]

Cool, sounds good!

[Bigglezworth]

Great minds think alike, huh Tim? How you been?Still dealing with a gremlin.... In all honesty not spent a lot of time to figure it all out. It will come in time. lol

[ttboost]

Still dealing with a gremlin.... In all honesty not spent a lot of time to figure it all out. It will come in time. lol

Ha..me too. been having too much fun driving it, rather than finishing up the last couple odds and ends...