Hello from Canada! Need vacuum advice for P11 running 54C with AEM standalone and MAP instead of MAF

Hi guys,

This is my first post, so go easy on me. :p
I've recently joined a GTi-R Facebook group as well so maybe some of you are on that page.

The issue I'm having is that no one seems to agree on anything when it comes to the GTi-R's complex vacuum system and I'm not sure how my own should be set up given my situation. Some say to leave it mostly stock, while others insist it's better to remove as much clutter as possible to make it easier to find leaks.

Here are the specs:
54C
block bored 0.20" over
87mm Wiseco 9.1:1 pistons
ARP rod bolts
ACL bearings
Cometic Pro full gasket kit
New OEM water pump, oil pump, thermostat

AEM EMS4
AEM pencil coils with 4 channel driver
GM 3 bar map sensor
AEM UEGO O2 sensor/gauge
GReddy 720CC injectors
Walbro pump
Large FMIC
3" stainless catless exhaust

The rest is standard, including the head, turbo, exhaust manifold, etc.

Right now the MAP is plumbed into the box just behind the intake plenum, but I'm not sure the readings are too great. It seems jumpy. I've considered the 4-1 vacuum mod across the nipples on the ITBs, but my tuner said to hold off so we could try it the way it is now. Do you guys see anything in the pics that could cause me problems? It feels as though there are an awful lot of hoses going to nowhere or missing altogether. I've looked at a few threads on here about vacuum but given that my situation is a little different I thought it might be wiser to ask directly. Sorry my engine bay looks like shit, I just thought I'd getting it actually running correctly before beautification. :p

Cheers for any insight you can provide. (Not quite visible in the photos is the BOV which is currently venting to atmosphere due to the hose being too old and short.)

I should also mention, we'll be doing an alpha-n dyno tune so that MAP sensor won't be QUITE as crucial, as the tune will be based mostly off the TPS.

When you say jumpy do you mean its idling rough ?

nomad wrote:When you say jumpy do you mean its idling rough ?

It's hard to explain really - it's more something we noticed when we were trying to give it a bit of a street tune before it went off to the dyno. The fuel map is just insane. One box will need double the fuel of the one beside it just for the car to not go full lean, even at really low RPMs. Fuel maps are supposed to look pretty smooth but I'm assuming the readings from the MAP are so erratic that the ECU is constantly getting wacky signals to contend with. The idle is actually pretty decent, but my start up needs work.

o2G2o wrote:

I hope, it help a bit:






I think, the endless rubber pipe is to the carbon canister (my car is a RHD, so strange to identify some parts):



http://www.gtir-motorsport-club.com/t628-vacuum-canister-thingy?highlight=canister
http://www.gtir-motorsport-club.com/t2613-charcoal-filter

As I know, it's connected the black box rear of the throttle bodies.
Try to plumb it, I hope it helps!