Not enough boost!!

[Ardz83]

Hi guys
I have put a boost gauge in my A4 and noticed im only boosting to 4psi max. I have checked for boost leaks and cant find anything. I unplugged the N75 valve and it actually seems faster.

Any advice would be great as to what else this could be???

Many thanks in advance
Dan

 

[Bradderz_1988]

Is it a 1.8t? If so 4 psi is actuator pressure ie the n75 unplugged. What psi are you charging the system to when checking for boost leaks?

 

[Ardz83]

Yeah as said 4psi is all im getting with the N75 plugged in and unplugged so does that kinda say the N75 is knackered?

 

[Bradderz_1988]

Yes I'd go with the n75 as it your first point of action as your symptoms are bang on for a faulty n75

 

[Ardz83]

Nice one pal. Which is the standard letter? is it C valve?

 

[Bradderz_1988]

Think F is the standard there's one on eBay - 260840680580

 

[aragorn]

Fault codes first!

It might be intentional, certain faults will cause the ECU to cut boost.

 

[Ardz83]

I have not got a vag com thing.

 

[aragorn]

Get one then, spending £10 on that is much more sensible than throwing money randomly at various parts that may or may not be faulty.

 

[Ardz83]

Replaced n75 and no joy still 4 psi!

 

[Bradderz_1988]

You need to have it scanned before anything else or check where you've plumed your gauge in.

 

[Ardz83]

Could it be the wastegate stuck? It did look abit rusty down there.

 

[Bradderz_1988]

I'd get it scanned before you even try the wastgegate as Aragon said previous certain faults will cause limp mode also get that pipework checked out as I was trying to chase what I thought was a boost leak on mine with no fault codes stored and even pressurised the system to find a small leak that only gave me 4psi at times from the vac line for the dv but sorted that and I saw 6psi after that (should off been 12-14psi and it was the wastegate plate it was just letting gases past it as it was wedge to the housing any way it landed it had worn that much I'm just surprised it lasted that long well it got 125k if it was the one from new.


here's the little fecker -

 

[aragorn]

Ardz: I've been telling you for weeks, you NEED to scan the car and find out whats actually wrong with it. Simply replacing random parts will get you nowhere and just waste your money.

If your still driving around with the MAF unplugged, then you'll certainly not get any more than 4psi.

 

[sam80quattro]

what is standard boost for an aeb?

 

[Bradderz_1988]

6-7psi iirc