Quick overboost question

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m8arx

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Hi folks, need a little bit of clarification here.

I have an AMK S3, standard apart from a badger tip, jetex cone and forge recirculating diverter valve. I have a pressure guage plumbed in, and sometimes i've noticed the car overboosts to 2 bar! Most times it sits at 0.5-0.7bar.

I have 2 questions -

1. if i electronically unplug the n75, what should the standard boost be?

2. If its more than it should be, then would it be worth screwing the bolts on the actuator rod towards the wastegate to bring it down to what it should be? The reason i mention the actuator rod is because The actuator rod was either extended or shortened when i first got the car by a company trying to diagnose a boost issue.

Cheers
 
m8arx said:
Hi folks, need a little bit of clarification here.

I have an AMK S3, standard apart from a badger tip, jetex cone and forge recirculating diverter valve. I have a pressure guage plumbed in, and sometimes i've noticed the car overboosts to 2 bar! Most times it sits at 0.5-0.7bar.

I have 2 questions -

1. if i electronically unplug the n75, what should the standard boost be?

2. If its more than it should be, then would it be worth screwing the bolts on the actuator rod towards the wastegate to bring it down to what it should be? The reason i mention the actuator rod is because The actuator rod was either extended or shortened when i first got the car by a company trying to diagnose a boost issue.

Cheers
Click to expand...
Hi with the n75 unplugged you should be seeing 7psi - 0.48 bar witch is actuator pressure.
 
Cheers s3ben, so by logic, if i get more than 7psi, i can try and adjust the actuator rod by making the end of the rod longer, and if its less than 7psi i do the poopsite with the rod.

If its 7psi with the n75 unplugged and i dont see any overboost - would this suggest a n75 problem or is there anything else that could affect it?
 
Do you have vcds or run a scan with to see if there are any faults?
 
Yes i have full vagcom and a offical hex usbII cable.

MAXIMUM LIMIT EXCEEDED was the error if i remember right
 
Ok i've took the car out a drive after disconnecting the n75 electronically - the car/boost is still the exact same. Is it worthwhile adjusting the actuator rod like i said above or am i barking up the wrong tree? I logged it with vagcom and it was peaking at around 2100mbar before dropping off
 
m8arx said:
Ok i've took the car out a drive after disconnecting the n75 electronically - the car/boost is still the exact same. Is it worthwhile adjusting the actuator rod like i said above or am i barking up the wrong tree? I logged it with vagcom and it was peaking at around 2100mbar before dropping off
Click to expand...

plumb boost direct to actuator.. that will check actuator
you may have a faulty n75 hence the over boost
 
Bill do you mean bridge the 2 hoses going into the n75 together? One from the charge oupe and one from the wastegate/actuator?
 
Sorted, hold steady at just under half a bar......confirming the n75 is gubbed.

Cheers for the help folks.
 
i've bought a replacement N75 brand new from VW (it is the correct part) and the car is still boosting to 1bar then dropping back again. I thought by bypassing the n75 and connecting the actuator straight to the charge pipe and getting 0.5-6 bar pointed towards the n75 being faulty? surely i can't have bought another faulty n75?

anyone like to suggest anything to me?

I cleared the codes before i changed it over, then took it a run, and then rescanned it with vcds and it didn't show any errors / fault codes.
 
Isn't standard boost almost 1 bar? 12psi if I remember correctly?

Then you have to take into account how accurate your gauge is.
 
the car goes just slightly over 1 bar, which is 14psi. so it probably goes to about 16psi then drops back to about 10-11psi (around 0.7-0.8 bar)
 
mine is overboosting at the mo. going to 28psi at times which is not good when its standard :(
 
not driving it on boost as i know it will cause probs. not sire for certain as im using that torque app so not sure how accurate that it. will unplug the n75 later and see if it still does it :)
 
unplugged the n75 when for a drive and it didnt really boost was very crap and very sluggish most itmy boost guage said is6psi but it didnt even feel like that. plugged it back in on the way home and it was back up to around 20+psi.
 
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