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View Full Version : Car not boosting right, any ideas?



sixfiveoh
08-04-2007, 03:05 PM
Okay, so after taking my car to the shop and them telling my turbo was blown, I wanted a few second opinions, since I pretty much could tell by driving it that I still had a turbo. I went up to a forum members house today and we vag'd it and logged it, the vag gave me this code

17956 n75 solenoid valve partially open

Then we hooked it up and logged it and made some runs. On idle, the pressure was fine, but when I hit WOT, I wasn't pushing as much as the car was requesting. Should be around 1600mbar, I believe and my car was only hitting 1400mbar.

Any ideas? Internal boost leak? Bad valve? Maybe need a new DV?

aytheory
08-04-2007, 03:08 PM
http://wiki.ross-tech.com/index.php/17956/P1548/005448

aytheory
08-04-2007, 03:09 PM
http://wiki.ross-tech.com/index.php/Category:Fault_Codes

sixfiveoh
08-04-2007, 03:10 PM
Hmm... I wonder if a faulty connection could have been cause when my friend was screwing around with my wiring when installing a turbo timer? How can if it's the valve or not?

aytheory
08-04-2007, 03:13 PM
just replace it with someone else's valve takes like 10 mins and you don't have to pay like 75 dollars to see if it is a faulty valve

sixfiveoh
08-04-2007, 03:52 PM
The N75 is the bypass valve, right? That's the same thing as a diverter valve, right? I'm planning on upgrading my diverter anyways, is now a good time?

dukez
08-04-2007, 03:57 PM
No its not.

sixfiveoh
08-04-2007, 04:01 PM
The Boost Pressure Controle Valve isn't the bypass valve?

speedydragon
08-04-2007, 04:12 PM
go with a stronger n75 valve, like the n75J race valve ^^ adds 1-2psi

sixfiveoh
08-04-2007, 04:15 PM
Where can I buy it? I hope it's the valve that's bad... how can I be sure it's that and not a faulty connection?

pinky
08-04-2007, 05:18 PM
n75 controls the wastegate

speedydragon
08-04-2007, 05:20 PM
Where can I buy it? I hope it's the valve that's bad... how can I be sure it's that and not a faulty connection?

I believe you can buy it at the local vw dealer. if not, you can buy it here http://www.ecstuning.com/stage/n75-info.html

sixfiveoh
08-04-2007, 05:22 PM
I'm thinking about ordering it from ECS, but check out this thread... the guy said he took it out again because the boost was "too extreme"

http://fastaudi.net/cgi-bin/forum/forum.pl?board=general;action=display;num=10438122 78

Sounds like a good thing, but COULD there be any negative effects on the turbo?

aytheory
08-04-2007, 05:27 PM
not sure - but if i can recall correctly - dbw cars which is yours can benefit from a upgrade N75 - ndbw can't - the DV is not the same as a N75.

go buy it from mike at purems.com or joe @ axismotorsport - two of the best - screw ecs they can suck me

sixfiveoh
08-04-2007, 05:31 PM
Alright, sounds like I could benefit from it whether my N75 is faulty or not, so might as well go with it... any way I can determine if the problem is a short circuit tho?

sixfiveoh
08-04-2007, 05:33 PM
So this
http://www.purems.com/products/product.php/II=1710
just looks like an OEM replacement as compared to the ECS one tho, right? Or will I feel pretty much equal gains with both? The guy in the thread I posted said the ECS race valve gave him 4psi over stock...

speedydragon
08-04-2007, 05:40 PM
So this
http://www.purems.com/products/product.php/II=1710
just looks like an OEM replacement as compared to the ECS one tho, right? Or will I feel pretty much equal gains with both?

the problem with that, is that you don't know which version it is. There are many versions of the n75 valve, like n75h, n75k, n75j and w/e else there are. Some of them will make you go into limp mode, especially if you're gonna go get chipped.

sixfiveoh
08-04-2007, 05:41 PM
So you're telling me I'm better off going with this? http://www.ecstuning.com/stage/n75-info.html? What valve is that, N75 what? I can't go to the dealership and say "I want the N75 RACCCCCCCCCCCE please" will they know what I mean? haha

speedydragon
08-04-2007, 06:32 PM
haha..i think you should be looking for the n75j vlave. i believe the "k" valve will make you go into limp mode when you're chipped.

sixfiveoh
08-04-2007, 06:48 PM
So the ECS one will be fine, correct?

speedydragon
08-04-2007, 07:58 PM
So the ECS one will be fine, correct?

now that I've read the advertisement, I'm not sure :| you can call them up and ask or just wait til monday and go to vw dealer.

sixfiveoh
08-04-2007, 08:02 PM
You think it'll cause me to go into limp mode when chipped? Because their little chart thing says it's compatible on a 1999-2002 A4 chipped...

sixfiveoh
08-04-2007, 08:08 PM
Okay, here check it out...

1.8T N75 Valves

1.8t N75 valve (version C): The N75 valve controls the wastegate of your turbo. This is a direct replacement for your OEM stock 1.8t N75 valve. This valve is from a 1.8T AWD motor and is the smoothest boost delivery of all the valves.

1.8t N75 valve (version J): This is the N75 valve from an Audi TT 225. The installation of this valve may cure surging issues and regulate boost pressures with possible boost level gains! More Power! A perfect balance of power delivery and increased boost levels!

1.8t N75 valve (version H): Want extra PSI? Just with the installation of this valve you can increase the whole turbo boost range by up to 3 PSI. More pounds of boost will give you additional HP due to the characteristics of this valve. This is also known as N75 RACE valve!

From http://www.tyrolsport.com/vwperformance.htm

Dunno which to go with...