BAC Not working S5 Turbo
 

Alright,
I have checked the resistance of the bac = 11.9
I have put 12v and ground to the bac = clicking
I have checked the resistance of the wire for pin 3q and the bac connector = 0
I have checked the resistance of the wire for the ground for the bac connector = 0
The bac does not click when the key is turned to on,
nor does it open fully when the key is in the start position,
I have to BAC's here and both have the same result.

When I check the Voltage with the key in the on position I only get about 2mv at the bac connector. Does anybody have any ideas as to why this might be?

Thanks

I have also tried another s5 turbo ecu and still the same problem exists.

Everything was working just fine like 100%. Then the other day I went for a drive on a hot day like 23 deg C and it was a slow drive about 35mph (60kph) or so and then I came up to a stop sign and suddenly it was not idling properly it was barely staying running without my foot on the pedal everything else ran just like it should except for the idle. I tried swaping out the BAC no good. So here I am trouble shooting and cannot figure out what is going on, why the BAC Valve is not functioning properly.

It has two wires. One is black/white. Does it have batt voltage on it when the key is to ON?

Are both terminals in the plug on the harness even with each other? One pushed back a bit?

If you have 12v on the black/white wire, then I'd pull the plug off the ECU and pull the plugs off and ohm out that wire that is NOT black/white from end to end to see if it's an open wire.

If you have 12v on the B/W and the other wire rings out from end to end, and the BAC works when you put a gnd and batt voltage on it's pins, then it's a ECU problem. Why two bad ECU? got me. Not likely unless the two wires in the BAC plug are shorted together and killed the transistor in each ECU. So make sure both wires in the BAC elect plug are not shorted together (eyeball).

There should be 12 on the black/white wire. No sense looking for voltage on the other wire. Just make sure the other wire has continuity from the BAC plug to the ECU.

Ok I have 12V on the Black/white wire on the BAC plug.
The Blue wire (other one) traces back to the ecu with 0 resistance,
They are not shorted.,
Both pins do not appear to be pushed back so to my knowldge the ECU is not activiating the Solonoid, is there a reason for this?

Ok,
I have the car idling properly with the connector grounded. However I would like to have the BAC working properly to help with HOT starts. Anybody have any ideas?
If I were to open the ECU can you let me know where I should be looking for burnt circuits.

Any ideas?
I reset the TPS (properly)
I Changed the BAC plug, I checked the wires running back to ECU, all Ohm out to zero, If i check the resistance between the two pins on the BAC connector they show infinite resistance, so they do not seem to be shorting.

I am at a loss I would love to ensure the BAC is working.

Any thoughts/ideas I would love to hear them.

I've no idea on a series five ECU. I've replaced the transistor on a series four ECU before using the following article: http://www.teamfc3s.org/info/articles/idle.html

Maybe you can glean something out it. I've never seena a series five ECU but know it's internals are different.

Ok to revive a thread without an answer. I have tried three ECU's one known to be working and good... three BAC's two be known and working well. Also tested the wires and no breaks.... there must be something that is causing the ECU to not run the duty for the BAC valve... anybody with any ideas?

i'm not an expert at this but i had the same problem. what i did to fix it was cut wires at the harness of the bac and then run new wires and spliced it to the ecu. you said you checked the wires for breaks, so i'm not sure if this will fix it, but this worked for me. good luck

I used temporary backprope wires run from the ecu to the bac valve and the result was still the same. I am thinking the ecu is missing a signal that triggers the BAC valve but unlike the honda crews there is very little knowledge of our stock ECU's.