N75 Resistance

**Squarrl** · 10-02-2008 08:52 PM

I think my N75 might not be working since my car isnt boosting past 10psi unless i build the boost slowly on the highway then i can hold up to 20psi. I measured the resistance of my N75 which i assume is a C. I found these values.

test the impedance of the N75

here are the acceptable ranges (copied from AW):

058-906-283-C 20-30 ohm
058-906-283-F 25-35 ohm
034-906-283-H 25-45 ohm
034-906-283-J 20-40 ohm
034-906-283-K 20-40 ohm

mine is 31.5ohms would this mean its bad or is there some play to these values?

**onepoint8tee** · 10-02-2008 10:13 PM

Sounds good. But a more accurate test might be to use vag com to watch the n75 cycle.

**Squarrl** · 10-02-2008 10:27 PM

how can i do that?

**onepoint8tee** · 10-02-2008 10:40 PM

I don't know the procedure exactly, only heard of people doing it. I suppose you would find the measuring block in the engine control module that refers to boost regulation or something similar and watch for a cascading and linear change in #'s as boost is being built.

You wold also want to watch actual vs requested boost by ecu at the same time.

**Squarrl** · 10-03-2008 09:16 PM

I read that if you unplug the electrical connector on the N75 you should hold more boost... I tried this and it only held like 5psi does this mean that I have this backwards and the wastegate can hold 5psi without N75 and the N75 is working and it is another issue?

**djwimbo** · 10-04-2008 08:39 AM

Originally Posted by Squarrl

I read that if you unplug the electrical connector on the N75 you should hold more boost...

that's not how it works. Leave the N75 electrically plugged in, even if you're not using it.

You can do a setup like I have with a cheap "bleed" style MBC and the stock N75(or any N75 for that matter). With my setup I'm boosting/holding the same amount I would before on a spike. That way power delivery is a bit more smooth. Unfortunately it's a bit touchy. It'll hit 5-7psi with the most minuscule amount of pedal movement.

Back to the OP, 31ohms isn't too far out of whack, I wouldn't jump the gun on that one. If you unplug the N75 you should go into soft limp mode anyways, leave it plugged in.

If you have VAG-Com, go into "Engine", then to "Output tests" (engine not running). You should be able to go through the list until you see something that says "N75 solenoid". It should automatically start cycling when it's highlighted. Stick your head under the hood and you should hear it, or be able to feel it if you touch the valve.

**Squarrl** · 10-04-2008 04:24 PM

I have only shareware version so cant do that test :(

I am going to pressure test it again.

**djwimbo** · 10-04-2008 04:29 PM

Do you have the correct spring in your DV?
Check the rod for the wastegate, make sure it's not loose or bent or something. I'm not really sure what to tell you. All our GIAC X customers are hittin a good amount of boost, all the time.