I will have two MAP sensors under the dash (electronic boost gauge, and AEM FIC). I am confused on the requirements of the vacuum/boost line(s).
I understand that it's ok to run a single line through the firewall and tee both sensors off it? Does the inner diameter of the line matter? Does the length of the line matter? Does it matter which line on the IM do i tee off of (I'm thinking brake booster)?

I am not really sure if the line can be too long or to small (in diameter) to "delay" the signal to the sensors? Also, what kind of line should I be getting (silicone, rubber)?

The boost gauge sensor came with a small inline "filter", is it a good idea to use that on the line going through the firewall, before teeing into the two MAP sensors?

 

The filter is needed at least for the boost gauge unit. The brake booster line is also kinda big to tee off of. As for size of line it doesnt really matter, just tee off and use whatever size the fitting is on the map sensor and sending unit. There shouldnt be any kind of delay or anything like that. The only line I know you should be accurate on is for the wastegate get that signal directly from the turbo.

 

Cool. Is the FPR vacuum line a better line to tee off of? And what is the best way to get it through the firewall, can I use any existing grommet?

 

i like to tee off the FPR that way if the vaccum hose slips off the FPR (lowering boosted fue lpressure) you'll see it on your gauge

in your case a tib already has a vacuum line going to the interior of the car for the heater you could also use it to hook up your gauge and FIC

shorter and larger hose will give you a faster response time while longuer and smaller hose wil lbe slower

don,t t off the brake booster ,there'sa check vavle in it and it does affetc the operation of the gauge and FIC

 

^ Awesome, thanks for the info.
If I use the heater line, would changing heater settings cause a temporary change in the pressure as seen by the FIC? Should I care?

 

nah shouldn't be a problem,
but
i was thinking of that today and i'm quite sure that there's a check valve near the engine...
if you use thios vaccum line you'll need to remove it and this might cause problems to the heather control...

you'll be better with a dedicated line starting from the FPR instead

sorry for the hopes ;-)

 

Haha, that explains why boosting doesn't screw up with the heater controls.

Thanks for all the help!

 

yeah, we were going to use this for the P&P MS ECU, but those check valves... LOL Anyways, the check valve presents one problem, the other, if you follow that line out to the engine bay, is the big ass vacuum tank in there.

I can't remember everything behind it, it's been about a year.

 

Ok, I am having trouble finding a way to get the boost line through the firewall..

I know about the fender route (through the sunroof drain grommet), but it seems like that would be too long for a boost line, plus I already have a 4awg wire through that grommet..

I've been trying to drill a hole through the firewall, but it seems impossible.. I can't get the drill at the right angle, and the bit just slips off the metal.. Can anyone who did this shed some light on how to do it properly?

I also know about the grommet near the TB but has anyone actually got a boost line through that one? I can't even see the other side from underneath the dash.. and i'm afraid i'll screw up the wiring if i just drill a hole through the grommet.

 

Line length isn't really an issue - yes, shorter lines respond faster, but the time to pressurize a line isn't that long either. Every modified car has to deal with running somewhat lengthy lines to the inside of the car.

I wouldn't use a grommet that is already being used, you may run into more problems trying to force it through along with stock wiring/wiring you placed. Drill a hole in the firewall, or drill a hole in the floor and run it up through there.

You can drill into the firewall - start with a small bit and work your way up to the size you need. Just takes a little bit of time.

I have the heater lined teed off - but its teed off right at the intake manifold, so I'm guessing I don't run into problems with the check valve that way as my RRFPR has had no issues.