rustbucket

iTrader: (1)

heres the deal, my car wont idle without me playing with the gas, it starts and runs for 2 seconds then dies, heres a couple concerns i have.

first of all, I did the emissions mod and it was my understanding that i was supposed to block off the plumbing to the BAC, i have it connected to the harness but no coolent going through it.

second is that my o2 sensor is not connected, for the life of me i cant find where it connects to, i think the plug broke off of the harness wire so i cant identify the connection, if someone knows exactly where the wire goes into the harness so i can hardwire it that would be fantastic.

just a little background i have an s4 car but am using the s5 core, upper and lower manifolds, the s4 throttle body, and s4 bac, s4 cas.


any thoughts would save me from more hair falling out thanks.

meteoro

spark...

coolant...

check out!

Blackfc3srx7

iTrader: (1)

Did you re check your timing? Recheck all vaccum leaks and the coolant is routed through the bac to the thermo wax for cold start. I know if you delete the thermo wax then cold starts are sometimes though but should be ok if you adjust the screw on the throttle body.

RotaryRocket88

iTrader: (7)

1. Bypass air screw
2. TPS
3. Variable resistor
4. Throttle cable (snug, but not so tight that the throttle stays open)

The O2 sensor will not affect whether the car idles, but you'll be getting crappy mileage. The wire comes off of the engine harness near the primary fuel injectors. It is underneath the UIM, so it will take some searching to find it.

Also, the BAC is not an emissions device. It's just there to supply extra air at startup and when the AC compressor or power steering pump are engaged. The water that is passed through it is just to keep the solenoid at a constant temperature. I have mine bypassed from the water pump straight to the thermowax, and haven't seen any difference.

Here is a pic of my setup. S5 UIM on an S4 block. I used my S4 TB and BAC. You can see the O2 sensor plug (green) by the heater hose on the left.
http://members.***.net/kiljaden84/S5%20manifold%202.JPG

rustbucket

iTrader: (1)

so if i have no coolent going through the bac this wont effect idle?? and neither will the o2 senser? well i cant find any more air leaks so if it is the tps would the car not keep idle at all b/c it sounds like it would but be crappy it that was the problem.

RotaryRocket88

iTrader: (7)

Nope. BAC water flow and O2 sensor won't affect it.

Bad or misadjusted TPS symptoms are usually roughness or a bouncy idle when the car is warming up or even when at the warm 750 RPM idle.

First thing to do is jack up the amount of air going into the motor at idle. Open up the air bypass screw and tighten the throttle cable. You won't be able to adjust the TPS until the car will hold an idle at operating temp. You can't do it when cold.

TPS resistance testing: http://howto.globalvicinity.com/gv_w...i=58&co=1&vi=1

Ideally, you will have 1.0 DC volts with a multimeter's positive lead connected to terminal "A" and negative on the battery ground.

******* Again, only adjust the TPS when the car is warm. *******

Chuck

iTrader: (2)

Do you have any idea how many crank and die idle problem threads are in this archive? Hint here is to run a search. Crank & dies mean there is too much unmetered air getting into the system. That means vacuum leak. Check all the vacuum lines, but don't stop there. Also check the gaskets at the Throttle Body and the intake manifolds, UIM and LIM. Vacuum leaks can also happen at the injectors when the grommets or O rings go bad. There are a lot of places to check. Its not fun and it takes a lot of time. Before you start turning this screw and cranking up that one, you might want to eliminate vacuum leaks as a possibility.