N75 Valve Question

[Mr Roboto]

Regarding the N75 which I need to replace. Is it worth investing in the ECS race N75 valve or just stick to the standard SEAT one and save about £20?

 

[DPJ]

Stick with a standard one.

 

[Mr Roboto]

I take it that a faulty N75 can cause boost hesitation without causing a fault?

If I disconnect the MAF then the cars runs fine.

MAF has been replaced 3 times to rule out a duff one.

On lite throttle I get boost hesitation which makes the DV dump loads of times then a surge of boost.

Am I going in the right direction with the N75?

 

[Mr Roboto]

Any one?

 

[Witalik]

i have got this too after my remap. when driving 100km/h en i want to accelerate with only little gas it also hesitates spool no spool kinda thing....

tomorow i get my hoses checked for leaks or anything and if that aint work i could wel be the n75 or the maf, not much else that does anything with the boost ? (wastegate)

 

[Witalik]

with mine got today to a garage, and both the TIP en the other hose on the turbo were lose and or faulty,

i got a little les hesitation now but it is still there...

so i dont know if the n75 is the only thing here that could cause this ????

 

[Mr Roboto]

Is it safe to go for a quick drive with the N75 unplugged or will this cause damage?

 

[Dani_b19]

Its fine, you'll just get a flat spot between 2500-5000 rpm, just dont do it for too long.

 

[wayne lcr]

good point mine got a bit of a flat spot it dint do it when i bought it just in the last few months any idea what it could be?

 

[wayne lcr]

and what is a n75 and were is it sorry old school lol

 

[Pabs]

Is it safe to go for a quick drive with the N75 unplugged or will this cause damage?

From my understanding, the N75 routes boost pressure to keep the wastegate CLOSED. With it disconnected, it'll never open, meaning that the pressure will always be routed to keeping the wastegate closed... thus overboosting.

The N75 bleeds off boost to the TIP in order to allow the wastegate to open.

 

[Witalik]

what is meant by getting a flat spot ?

i thought this valve is used to open the waste gate ? if it is unplugged it wont open ? if u have a mapped car would that be to much boost ?

 

[Rarpuc]

On my previous car (octavia vrs) which had the 180bhp 1.8t after a remap i got pretty awful hesitation,initially i changed the n75 for a new standard one but the problem remained i then went for the ECS race n75 and it all but solved the hesitation. it would still crop up from time to time but it was no where near as bad as it had been.

 

[paul-murphys]

With the n 75 disconnected the boost won't boost to full as wastegate will open at actuator pre set pressure. correct me if i'm wrong.

 

[Pabs]

Paul-Murphys - I think you've got it wrong - see here:
http://forums.audiworld.com/showthread.php?t=1476692

 

[ibizacupra]

From my understanding, the N75 routes boost pressure to keep the wastegate CLOSED. With it disconnected, it'll never open, meaning that the pressure will always be routed to keeping the wastegate closed... thus overboosting.

The N75 bleeds off boost to the TIP in order to allow the wastegate to open.

nope.. not quite

with N75 'electrically" disconnected all boost pressure route to actuator, which when it gets past its spring pressure of 5psi (approx) it then opens, so max boost is actuator pressure.

n75 keeps wastegate closed when its on full duty cycle maximum on, so routing most of the air to the intake pipe so the actuator does'nt see boost so does'nt open, thus being uncontrolled boost until n75 duty cycle drops down again.. (ecu controlling now for target vs actual boost request)

regards
bill

 

[Pabs]

lol - i always seem to get it the wrong way around!
So what you're saying Bill, is that the normal state, n75 is always "closed" thus pressure routing to actuator, opening this earlier than it should - so you'll never see more than 5psi of boost with N75 disconnected.

Correct? (I hope so!)

So to achieve higher boost, the N75 bleeds it off to the TIP to keep the wastegate closed.
Phew - I think I'll keep this thread bookmarked for a read when I'm not so tired!

 

[paul-murphys]

yeah thats correct thats what was trying to say, n75 builds up boost by keeping actuator closed. with it unplugged cant build up.

 

[Mr Roboto]

Some thing is conflicting with the MAF as with it disconnected the car runs perfect.

So is it wise for me to unplug the N75 for a sort drive or not?

What else can be linked to the MAF to cause my boost problem.

 

[Pabs]

Yeah mate - I think it's the way I read it confused me - the boost might build up, but the pressure through the N75->actuator DECREASES it to keep the actuator closed... (it is sent to the TIP instead).