How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask AudiDoc Your Own Question
AudiDoc
AudiDoc, Independent Audi Shop Owner
Category: Audi
Satisfied Customers: 6457
Experience:  I've been working on Audis since I was 18 and own an independent Audi repair and performance shop
14582033
Type Your Audi Question Here...
AudiDoc is online now
A new question is answered every 9 seconds

Audi A4 Avant: 01 audi a4 avant boost issues I have a boost

This answer was rated:

01 audi a4 avant boost issues I have a boost gauge and it boosts up too 14psi just fine to 3000 rpm then it drops to about 3 psi and holds sounds like waste gate opens this is a brand new turbo with 1000 miles on it I also live in the middle of no where how would I diagnose this issue

AudiDoc :

Hello, I'm Jason. I will do my best to answer your question quickly and accurately using the information you have provided.

AudiDoc :

Ok, so there are two real key pieces of equipment that would help us get through this

AudiDoc :

also, you mention 14psi....what software are you running, and did you replace with a factory turbo?

AudiDoc :

meaning Borg Warner K03

Customer:

completely stock everything oem replacment turbo

AudiDoc :

ok, good info, thanks. The 14psi part is the telling one

AudiDoc :

you're overboosting

Customer:

how do i adjut that at home

AudiDoc :

are you sure you hooked up the N75 boost solenoid back up correctly, and did you check the lines for any breaks?

AudiDoc :

it sounds like the N75 valve is not functioning, and the wastegate is just functioning off of spring pressure

AudiDoc :

the N75 is the part here with the electrical connector to it (ignore the red circle)

Full Size Image

Customer:

i did not personaly install it had a shop put it in spent alot of money getting that fixed so they installed it for free as a favor tranny went out spent alot of money with them so.they.did.me.a.favor guess not :(

AudiDoc :

ok, understood, and I'm not sure your mechanical ability or collection of tools, but this would be the first thing I'd have them check

Customer:

they are 300 miles away i am pretty good with wrenching on cars just not audi this is my first one so just check hoses and connections how.can i.tell if its bad?

AudiDoc :

The N75 valve....it's going to require a hand held vacuum pump to check connections, a multimeter to check the valve for 30 ohms across the connector.

AudiDoc :

Ideally, a way to check for boost leaks would be best

AudiDoc :

here is an excellent thread outlining exactly how this system works

Customer:

ok i have volt meter no vaccum pump would it be easier to.just replace or disconnect?

AudiDoc :

I wouldn't advise spending money on a valve on a hunch. I really don't think the valve itself is bad, but boost/intake/wastegate hose leak testing is VERY important here

AudiDoc :

either the valve may be installed backwards (you'll see the correct orientation in that link) or there is a leak

Customer:

any way to test that at home?

AudiDoc :

Test what, for leaks? Without a vacuum pump or smoke generator, nothing you can do beyond a visual check

AudiDoc :

here is another excellent post showing details of the system. It's about replacing the turbo, but there is other pertinent information as well

AudiDoc :

but please understand that visual checks are often not enough

AudiDoc :

unfortunately, there's only *so* much we can do through a computer screen, but the information should get you started

Customer:

i understand it appears to be installed correctly how would i check it with the vaccum pump and what should the readings be? 30 oms accross the plug i can do that

AudiDoc :

You need to use the vacuum pump to check integrity of the two N75 hoses, or remove them with the N75 to check for leaks or splits visually

AudiDoc :

botXXXXX XXXXXne is to use those pictures in both of those links to make sure that everything is connected properly and securely on the turbo inlet hose

AudiDoc :

but without a smoke tester or VAG-COM scan tool, any further testing will have to be left to a shop familiar with Audi

AudiDoc :

and being honest, the shop who did the installation should handle this, however I do understand the distance issue

AudiDoc :

if there are any further questions, you will receive a link in your email to respond back, as I do need to convert to email format out of live chat now

AudiDoc and other Audi Specialists are ready to help you
Customer: replied 4 years ago.

thanks ill see what happens

glad to help