Hi guys,
Usually it is a pretty simple job. Take the old battery out , put the new one in, connect everything and off you go.
Not so with our Falcon (AU Falcon Futura 4.0 automatic).
It only took five minutes to replace the old battery with the new one and after starting the engine, everything seemed to be normal. I put in the security code for the radio that I had to find first, I executed the throttle position calibration in order to re-train the automatic transmission and everything seemed to be fine.
Things changed when I put a gear in.
The moment I put any gear in (doesn’t matter which one), the idle drops so low that the engine nearly stalls and then goes back up to about 550 rpm.
It just drops for a very short time.
The same thing happens, when I approach a red traffic light. The idle drops so low while the car slows down so the engine nearly stalls.
But the most ridiculous part is, that it even happens when you slightly turn the steering wheel when stationary. I tested in my garage.
The moment you slowly and slightly turn the steering wheel to any side, the idle is steady at roughly 550 rpm (even when the power steering pressure switch closes).
But the rpm drops very low for a short time (engine nearly stalls), the moment you turn the steering wheel back to the centre position. The rpm actually drops at the moment, when the power steering pressure switch opens again (no more power assistance).
I remember from other cars, that the
ECU (ECC) needs to “re-train” itself for about 20 km after the power was disconnected which usually resets the
ECU.
I had a look in my maintenance book and I noticed that the power steering pressure switch gives an input signal to the
ECU and so does the transmission with a input “gear select” signal.
The
ECU then gives an output signal to the Idle air control valve at the air intake in order to adjust the idle airflow to keep the idle as steady as possible the moment I select a gear or turn the steering wheel.
It seems that the
ECU is a little bit slow with regulating and adjusting the
IAC Valve the moment the input parameter change. That’s why the idle drops and just before the engine stalls the
ECU realises that it has to adjust the
IAC valve so the engine doesn’t stall.
The issue only appears in gear. In N or P everything is fine. I can turn the steering wheel and back and the idle is perfect.
That is the weirdest thing the Falcon has done so far and just because I replaced the battery.
However, to keep a long story short I was wondering if anybody has experienced the same with their AU Falcon and if so what can I do, to fix that?
I hope it is just a slow learning
ECU (EEC) and after about 100 km it has fixed itself. But I doubt that.
So I would be more than happy for any information because I don’t want to go to a dealer or mechanic who would charge me just for the diagnosis and then tells me that it is going to be very expensive to fix it.
I love the AU but those little things are actually driving me nuts and I am pretty sure that you can replace the battery from any 70’s Falcon without having such annoying problems.
Can’t wait to get some feedback…..thanks guys
The Moose