Need help after I replaced the battery...

[Swedishmoose]

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

[XRGhia]

Just drive it and let it run - it'll go back to normal eventually...

[JimStone]

ECU Relearn sequence

Disconnect battery, depress brake pedal.

Reconnect battery, then:

2 min idle in park, A/C off
2 min idle in park, A/C on
2 min idle in Drive, A/C on
2 min idle in Drive, A/C off
5 - 10 min drive under varying throttle

This is required for the ECU to learn load and no load 0% throttle conditions; just driving and letting it sort itself out can easily find you stalled in the middle of an intersection with a truck bearing down on you.

[Dave_Obsession]

Last time I did mine it took around 100kms to re-learn itself...everything will be fine!

[Bushbasher]

What everyone has said, she'll be right. I had the same thing with my Fairlane when I did the battery swap even after I did the relearn sequence. It went away before too long after a couple of trips out.

Bushbasher

[Swedishmoose]

Hi guys...

wow, thanks for all the replies.....thats why I like this forum so much. I will try the relearn process for the ECU that Jim Stone mentioned and let her run for a bit.
i did about 20ks before I posted it and it didn't really make a difference. that's why I was worried.


Oh..by the way....does the brake pedal has to be depressed while reconnecting the battery?

thanks again

The Moose

[Bushbasher]

Don't know where the brake pedal thing comes from, I've never heard that one before. It's a bit hard to be in the car and under the bonnet at the same time, haha.

Bushbasher

[Swedishmoose]

Hi there,

well, i could ask someone to depress the pedal while I re-connect the battery.

It could be that it is just part of the sequence so the depressed brake pedal "prepares" the ECU for the learning procedure that follows.

I am not sure how a depressed brake pedal would have an influence on the ECU when the battery is disconnected.
So I assume that Jim Stone meant that depressing the brake pedal and re-connecting the battery should happen simultaneously....

Not sure..

The Moose

[robbyj]

iv even actually stalled mine twice while the ECU was relearning. Slowly turning a corner stalled it twice. Its not fun but it will re-learn

I'v head of people intentionally letting the ECU reset and re learn itself, and training it by flogging it basically.. so it learns to be more powerful? urban legend? hoon truth? who knows

[TheInterceptor]

Isn't the "depress the brake pedal" thing to get rid of the residual power in the system after the battery is disconnected? Problem is the brake switch isnt active without ign on...so hitting the horn would do that job after you disconnect the bat.

[AU Mont]

ive never done a re-learning process although ive heard about 50 different methods. However all my falcons drive spot on with a a day or 2 max, with minor dips in the idle in the meantime.

Alot of the time it finds the correct idle within 5mins after a reset

[mik]

i`ve never bothered with the relearn thing, to be honest, the times i`ve had the battery disconnected and reconnected, it did`nt even seem to run any different, other than the need for the radio code.

[JimStone]

Ford factory specified process to depress brake pedal - check with your nearest Ford Master Technician who did the pre launch AU specific training. Process is designated to bleed residual power from capacitors, etc in CPU rather than wait for an hour for system bleed off residual power.

Appologies for not being clear and skipping some basic steps in earlier post.

Sequence is -

Disconnect battery.
turn ign on.
Depress brake pedal.
Release brake pedal.
Turn ign off.
Reconnect battery.
Start engine.
Idle for 2 minutes in park, A/C off
Idle for 2 minutes in park, A/C on
Idle for 2 minutes in Drive, A/C on
Idle for 2 minutes in Drive, A/C off
Drive for 5 - 10 min under varying throttle %.


Your call to follow or not, I don't really care.

[auIILTD]

Originally Posted by JimStone

Sequence is -

Disconnect battery.
turn ign on.
Depress brake pedal.
Release brake pedal.
Turn ign off.
Reconnect battery.
Start engine.
Idle for 2 minutes in park, A/C off
Idle for 2 minutes in park, A/C on
Idle for 2 minutes in Drive, A/C on
Idle for 2 minutes in Drive, A/C off
Drive for 5 - 10 min under varying throttle %.


Your call to follow or not, I don't really care.

As someone that tunes and resets KAMS (Keep alive memory) on regular basis, the above is actually a double reset of KAMS. The way that I reset KAMs is to disconnect battery, foot on brake pedal for 2 minutes then reconnect battery. That is it. I can guarantee that is all that is required. Leaving the battery disconnected for 5 minutes will do the same thing which is what has happened to our OP.

The whole 2 minute this and 2 minutes that is another way to reset KAMs without disconnecting the battery.

There is absolutely no need to reset KAMs again - this will just prolong the bad behaviour. KAMs where reset when the battery was changed, causing the bad behaviour, so resetting them again I do not believe will assist the situation.

The reason that our ECUs have adaptive learning is to compensate for engine changes as it gets older and wears. Over the period from the last reset of KAMs, the ECU has adapted the fuelling of the car to keep it running at it's optimum. Resetting the KAMs has lost all of that learning, so as mentioned above, it just needs to lean again.

Also though, bear in mind that the car when started runs in open loop mode for 45 to 90 seconds. This means that the learnt memory is not taken into account during this time.

Hope this helps a little.

Hope it sorts itself out Swedishmoose.

Stu

[rowan194]

Originally Posted by JimStone

Idle for 2 minutes in park, A/C off
Idle for 2 minutes in park, A/C on
Idle for 2 minutes in Drive, A/C on
Idle for 2 minutes in Drive, A/C off

As well as A/C, I also put on headlights and rear demister. High electrical/mechanical load basically, otherwise the engine starts shuddering when it's idling in drive, with the demister on, and the A/C kicks in. (this behaviour is usually why I retrain in the first place)

[saber]

Originally Posted by mik

i`ve never bothered with the relearn thing, to be honest, the times i`ve had the battery disconnected and reconnected, it did`nt even seem to run any different, other than the need for the radio code.

Same here..if anything, the car ran slightly better after disconnecting the battery. Never had any low idle/rough running issue after a battery disconnect in either folks AUI and AUIII Falcons. Just disconnect and reconnect battery, plug in radio code, and drive.

[Mr Hardware]

Originally Posted by JimStone

check with your nearest Ford Master Technician who did the pre launch AU specific training.

they'd all be retired by now surely!!!!!

[supershifty]

AuIILTD, with the procedure described in your post - Do you depress the brake pedal for 2 mins with the ignition in the on or acc position, or doesn't it matter?

Cheers!

[auIILTD]

Originally Posted by supershifty

AuIILTD, with the procedure described in your post - Do you depress the brake pedal for 2 mins with the ignition in the on or acc position, or doesn't it matter?

Cheers!

Hi shifty. No, it does not matter about the key position. I forgot to mention that I usually turn the lights on high beam whilst battery is disconnected as well. The ECU has permenant power from the battery regardless of key position, so the idea of the brake pedal and lights (which also work regardless of key position IIRC) is to assist in draining any charge held in capacitors, and hence wiping the keep alive memory. This just makes the process quicker. Disconnecting the battery for 5 minutes does the same thing.

Stu

[Swedishmoose]

Hi guys,


well, first of all thank you for all the posts and the info. I wrote everything down and will disappear in the garage on the weekend. I was quite busy so I couldn't reply earlier and retrain the Falcon.

I will kepp you updated in case something goes wrong or some unusual behaviour of the Falcon appears..

Thanks again guys and have a great weekend...


Cheers...

The Moose

[auIILTD]

Cheers Moose. DO not reset the ECU memory again. Just drive it an let it learn again.

Cheers
Stu

[4ford]

My experiences are the same as MIK at post #12.

I've owned my AUII6 for some 9 years and several battery changes!

Cheers

[Swedishmoose]

Hi guys...

here is a quick update...

The driveability has improved a bit, especially when approaching roundabouts and traffic lights.

However, the idle is still dropping a lot when the steering wheel is moved while stationary and the car is in gear.

When the power steering is active (power steering pressure switch closed), the ECU is managing the idle quite well. But once I turn the steering wheel back to the centre position and the power steering pressure switch opens, the idle drops and the car nearly stalls.

The ECU can't handle the situation, when the power stearing is active and then becomes inactive again. It's even worse with demister and high beam on.

On top of it, the situation is worse once the Falcon has reached its operational temperature.
At first start in the morning when cold, it was actually not too bad (even the steering wheel was moved the idle was ok).

Well, I hope it will improve because otherwise I have no clue what that could be.


What do you guys think?


Cheers

The Moose

[smally289]

OK, got my flame suit on here, some people may not like what I'm about to say, but I am speaking from experience and offerring advice which is what the forum is all about.
I was a Ford Registered Technician during the time that the AU was released and also well before (back in the days of the XF). To restore a good idle after a battery change I find the best way is to leave the car idling in drive (no accessories on like A/C, lights etc) for 10 to 15 minutes. Pull the handbrake on and go and have a coffee if you like. You won't find this in any workshop manual or diagnostic training book but it works. As others have said, over time the PCM will relearn but this gives you a good idle straight away. I find it works best after the battery has been disconnected for 5 to 10 minutes.
Another way of changing the battery and not loosing radio codes or idle quality is to connect a jump pack to the battery terminals before removing the leads. Swap the battrery over, refit the leads and remove the jump pack. No loss of power to the PCM.

Flame away workshop manual geeks LOL

[4ford]

I agree entirely....

In my experience, the easy way to do this is to make up a two-core lead, only lightweight is necessary, about the same weight as the plug-in car vacuum cleaner.
On this lead, attach a cigarette lighter type plug on one end, and a couple of alligator clips on the other.
OK, so just before you disconnect the car battery, plug in the lead to the cigarette lighter plug with the other end attached to a small 12v battery.
Remember to get the terminals in the correct orientation, you probably have a negative-to-earth system, so make sure this temporary lead is wired the same.
So now you can disconnect your car battery and change it over, whilst the temporary 12v power supply keeps the PCM powered up sufficiently for there to be no ongoing effects.
When the new battery is fully installed and properly connected, you can disconnect the temporary 12v supply.
Job done, no engine idle(or any other) problems.

[rowan194]

Originally Posted by 4ford

OK, so just before you disconnect the car battery, plug in the lead to the cigarette lighter plug with the other end attached to a small 12v battery.
Remember to get the terminals in the correct orientation, you probably have a negative-to-earth system, so make sure this temporary lead is wired the same.
So now you can disconnect your car battery and change it over, whilst the temporary 12v power supply keeps the PCM powered up sufficiently for there to be no ongoing effects.

I had a quick look at the wiring diagrams for the AU, I think you'd need to have your key in the ACC position for your battery power to go beyond accessories such as the radio. In the OFF position there would be no electrical connection to the ECU and any other "always on" parts of the car.

[4ford]

OK, the PCU must be powered all the time the battery is connected, and the cigarette lighter plug is always powered with the battery connected, and there is only one battery!
The only exception to that would be if the cigarette lighter plug was only powered with the key in ACC or ON.

4ford

[rowan194]

Originally Posted by 4ford

The only exception to that would be if the cigarette lighter plug was only powered with the key in ACC or ON.

In my AUIII Fairmont the cig lighter is switched just like the radio. It is off when the key is at OFF or out, and briefly drops when the engine cranks.

[auIILTD]

Originally Posted by smally351

OK, got my flame suit on here, some people may not like what I'm about to say, but I am speaking from experience and offerring advice which is what the forum is all about.
I was a Ford Registered Technician during the time that the AU was released and also well before (back in the days of the XF). To restore a good idle after a battery change I find the best way is to leave the car idling in drive (no accessories on like A/C, lights etc) for 10 to 15 minutes. Pull the handbrake on and go and have a coffee if you like. You won't find this in any workshop manual or diagnostic training book but it works. As others have said, over time the PCM will relearn but this gives you a good idle straight away. I find it works best after the battery has been disconnected for 5 to 10 minutes.
Another way of changing the battery and not loosing radio codes or idle quality is to connect a jump pack to the battery terminals before removing the leads. Swap the battrery over, refit the leads and remove the jump pack. No loss of power to the PCM.

Flame away workshop manual geeks LOL

NO problems Moose.

Have you tried what is suggested in the quoted post? If that does not work, then you may have serious issues that may involve more investigations.

Stu

[Swedishmoose]

Originally Posted by auIILTD

NO problems Moose.

Have you tried what is suggested in the quoted post? If that does not work, then you may have serious issues that may involve more investigations.

Stu

Hi there,


yep, I did.
The only difference was that I have added another electrical load after every second minute.

I started the engine after I took off battery ground for 10 minutes and let it idle for about 2 minutes....after that I added the demsiter..than high beam etc.
After 15 minutes demister, aircon, highbeam, interior light, brake light, radio and fan were on.

Everything was fine in N and P (ECU and IAC kept idle at about 700) and when I put a gear in the idle tropped to about 500 and vibrations occured because it was obviously a little too low.
When i turned steering to left, idle was still at 500 (even with power steering pump running) and when I turned back to centre (no power steering assistance) the idle drops to 250-300 for 1-2 seconds and then goes back up to 500.

The Moose