yay, clusterfuck.


I've got the s5 UIM installed on my S4 engine. The engine runs, but will not idle on it's own. I have a S5 BAC, and I was just wondering what the different connections on it were?

Air from snorkle
coolant in?
coolant out?

and then the plug.

Where is the plug? Is it the same as the S4? Where do I run the coolant? lines?

 

First of all, if it won't idle on its own you have a vacuum leak likely. These cars can idle without a BAC or the fast idle/thermowax system, although not nearly as well. The first thing you need to do is check for vacuum leaks. You probably have multiple ones. I found this pressure tester very useful for getting the vacuum leaks taken care of so your car will run:

http://www.boostpro.net/prodtester.html . Buy the universal/DSM tester (or you can fab your own similar tester from home depot stuff). you may need a reducer coupler to make it work depending on your setup. I usually hook up the air compressor and then spray soapy water around the the engine bay. Turns out in my case I had leaky blockoff plates, a leaking IAT sensor, loosely fitting vacuum leans, leaky gasket on the thermowax... one thing after another.

Now, do you still have the thermowax/fast idle system on your throttlebody? If someone has messed with those screws (they are not normally supposed to be adjusted) your car may have an unstable idle. Also, do you have the stock ECU or a standalone?

 

the connector is different on the s4 and s5 BAC one is square s4 i believe the s5 is oval if i remember correctly.

 

Im having the EXACT same problem right now.
Im almost positive I have vac leaks, so Ill be tearing it apart tomorrow.
As for the BAC plug, I extended the line about a foot to reach to the other side of the manifold and soldered in a S5 fuel injector clip.
Since it wont idle on its own, I cant really tell if its working or now, but Ill recap tomorrow after I redo all the gaskets and vac lines.

 

The car idles rock solid at 1k with the throttle only slightly cracked.

Fast idle and thermowax have been removed.

I actually bought that pressure tester already and found the biggest vacuum leak and now the engine runs...it didn't run before. If I run 7psi into the intake via that tester, it slowly leaks out, but I can't tell from where. I just assumed it was leaking through the engine.

Anyone have a picture of a BAC installed on an S5? I need to know where to run these lines.

 

Take the rear BAC coolant line and replace the front with it, so that the rear BAC coolant line now runs from the front of the motor to the BAC. It will clear the S5 intake runners then.

Run a new coolant line from back of the BAC to the where the rear coolant line was running (cold idle assist thermovalve)

Take the old large AWS/BAC hose and connect it too the bottom of the S4 intake snorkle.

And if you use a S4 Turbo BAC, or it will fit between the rail and manifold okay, you just have to adjust the air intake to the BAC (torx screw on the side of the BAC intake retainer). The bog advantage is that then you only have to extrend the BAC wires to the passengers side of the motor, as the plug is the same for S4's, whereas you need to get a S5 plug to use the S5 BAC.

 

Wow, thanks for that...my engine is already stripped of all emissions stuff, but I should be able to figure everything out from that. Right now I have the rear coolant hose just tied to the front one, I guess I should have figured that out.

I don't have a connector for the S5 BAC, which I already have. I'm going to just crimp some wires inside the connector and then put an external plug on it. I'll check the FSM or test to see which side is positive and negative. If I hook 12v up to it with no coolant, it should still open, right?

Where are you running your injector air bleeds to? How about the brake booster? After that, I think I have everything all done when it comes to vacuum...

 

Looks like youve made some progress.
I stripped my entire manifold down to pieces and RTVd every gasket surface AND recalibrated the TPS.
I still cant get my car to idle.
How did that leak tester work for you? Im at the point where I may make one out of Home Depot stuff.

 

I think it's worth it, I found my first leak with it...it's just very hard to tell exactly where it's coming out. I want to borrow a fog machine or something, that would work much better.

 

I tied the air bleeds to the little line on the S4 intake tube that is right next to the big line for the BAC/AWS. But anything between the AFM and the Throttle plates would be fine.

Brake booster to the large line of the back side of the intake runners.

This is how I have routed everything when I have done that set up in the past:

 

My Home Depot leak tester was nothing but fail so I was wondering if you could tell me which tester you ordered from that site and where you tested from.

 

Did you buy the 3" universal tester and test from the coupler on the throttle body?

 

check out this link http://howto.globalvicinity.com/gv_w...co=1&vi=1&fl=1

- I found it very helpful. Also I used my s4 BAC on the S5 intake - I just extended existing wires & left the coolant lines off.

Ramses666

 

I didn't know the S4 one worked. Wow. I might just do that.

 

I couldnt get the S4 BAC to clear everything and still connect to the snorkel.
Shaolin, which pressure tester did you order?

 

http://www.boostpro.net/prodtester.html

I got the one near the bottom.

3" diameter, tire valve, w/gauge, $20+ shipping.

I had a 3" coupler laying around and I put it over it and then wedged the coupler inside the intake. That works, but I also wrapped about 15 layers of electrical tape around the tester (no coupler) and wedged it inside the TB elbow.

As for the BAC, I was not able to get the S4 one to fit. The inlet angle was all wrong and the plug hit the fuel rail.

I had the S5 one here, I soldered some wires into the socket, and then hooked a molex plug up to that so I could still unplug it from the car if necessary. Bolted right up. The outlet is pointed right at the snorkel and a 3" piece of hose fit perfectly. (I think it was the one from the S4 BAC). The only problem is it leaked a little so I had to put a hose clamp on the bac side of that hose.

 

The S4 BAC will work but is very tight with the injectors & fuel rail. You just have to get everything turned just right. & I mean it's tight!! Mine worked out fine. However if you are having problems it is a vacuum leak more than likely. The BAC is just a crude band-aid. You will know when it's right.

Ramses666