Northern Auto Tech - ECU and Blue & Me Repairs

Technical Start/Stop weird behaviour

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Technical Start/Stop weird behaviour

deeyup said:
Pull up at the lights, motor dies as expected, then tries to start again before changing its mind and cutting power, continues to do this intil you depress the clutch. :confused:
Happened 3 times this morning, and has happened once a month since I got the car.

Anyone else seen this happen?
http://youtu.be/iGg1Hf3e-7A
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Yes, that's weird. Personally I'd disable S/S until it's fixed to protect the ring gear. Presumably you still have warranty?

RobinPJ said:
My ignorant guess is a sensor somewhere that cannot decide one thing from the other.
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Seems eminently sensible to me. I'm also wondering if a combination of electrical devices drawing just enough current to almost inhibit S/S operation could do this. I'm glad I don't have to diagnose it, though I'd start by turning the drl's off to see if it made any difference. It might be worth noting exactly what's switched on when the problem occurs to see if you can find a common factor.

Whatever the cause, I hope you get it sorted without too much hassle.
 
Yes, sensor sounds about right, maybe the clutch pedal? or one of a thousand others??

DRL's were on, climate on (with aircon off) radio on

I'll drop it in and leave it with them. I'll see if I can have a new Panda to play in for a few days. :) turning a negative into a positive.
 
Mine did the opposite yesterday, decided it was going to stop, and then changed its mind. The starter didn't engage, but fuelling and ignition was restarted just before the engine fully stopped, so it jumped back into life. I was rolling along at around 4 or 5mph out of gear, clutch pedal up, and the coolant temp was just on the second blob of the gauge.

Me thinks a bunch of thresholds were *just* over what's required to stop the engine and then it decided not.
 
bgunn said:
Mine did the opposite yesterday, decided it was going to stop, and then changed its mind. The starter didn't engage, but fuelling and ignition was restarted just before the engine fully stopped, so it jumped back into life. I was rolling along at around 4 or 5mph out of gear, clutch pedal up, and the coolant temp was just on the second blob of the gauge.

Me thinks a bunch of thresholds were *just* over what's required to stop the engine and then it decided not.
Click to expand...

I reckon you were probably at the cross over speed between motor on/off. Were you rolling down a hill?
Or maybe motor temp?
 
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Common misconception that the alternator will charge a battery up fully, it won't. All it does is replace what was lost in the start up cycle.

You need to use a smart/trickle charge to bring the battery up to full capacity - something a lot of dealers don't do during PDI and before they take the car out of transport mode..
 
bgunn said:
Common misconception that the alternator will charge a battery up fully, it won't. All it does is replace what was lost in the start up cycle.

You need to use a smart/trickle charge to bring the battery up to full capacity - something a lot of dealers don't do during PDI and before they take the car out of transport mode..
Click to expand...

Ive got 2 CTEK's running the occasional use V6 GT & S4. Will hook one up to the diddy car over the weekend(y)
 
Mine does the stop and start straight back up again, but it's fine during the warm weather months. I put it down to an outside temperature thing as whenever it's 10 degrees or less it stops playing ball. Maybe I'll try out the trickle charge trick.
 
bgunn said:
Common misconception that the alternator will charge a battery up fully, it won't.
Click to expand...

Yes it does.

Most modern alternators have smart chargers in them, which will charge until at capacity and then cut out, reducing the load on the engine.

Also, if what you say is true, what happens if the battery is fully charged and you start the car, will it not be returned to fully charged :confused:
 
Most Easterly Pandas said:
Yes it does.

Most modern alternators have smart chargers in them, which will charge until at capacity and then cut out, reducing the load on the engine.

Also, if what you say is true, what happens if the battery is fully charged and you start the car, will it not be returned to fully charged :confused:
Click to expand...

All alternators have voltage/current regulation - otherwise your battery would explode/boil dry. There's nothing 'smart' about this, it's a case of simple battery sensing - on a 'conventional' alternator, the field coils are excited by the battery voltage (which is why the battery light comes on when the alternator doesn't turn - the coils form a complete circuit with the bulb in series), and when the alternator starts turning above what's called 'excitation speed', it then is considered 'self exciting' and the battery light goes out.

An alternator will only give what's called a 'surface charge' - i.e. put back in what was taken out. You need a deep cycle trickle charge (and CTEK chargers are smarter still) to fully recharge a battery - an alternator will never do this.
 
bgunn said:
All alternators have voltage/current regulation - otherwise your battery would explode/boil dry. There's nothing 'smart' about this, it's a case of simple battery sensing - on a 'conventional' alternator, the field coils are excited by the battery voltage (which is why the battery light comes on when the alternator doesn't turn - the coils form a complete circuit with the bulb in series), and when the alternator starts turning above what's called 'excitation speed', it then is considered 'self exciting' and the battery light goes out.

An alternator will only give what's called a 'surface charge' - i.e. put back in what was taken out. You need a deep cycle trickle charge (and CTEK chargers are smarter still) to fully recharge a battery - an alternator will never do this.
Click to expand...

Smart charging alternators are more than just a regulator on an alternator. What you've described there is typical of a charging unit on a car in the 70/80 and even early 90s, most cars in 00's are far more advanced than that, and what your saying about alternators never charging the battery is simply illogical.
 
The 'smart charger' you talk about is simply the ability for the engine management to control the alternator output on demand, rather than the alternator regulator pack doing it without any outside influence. If you read how they work, it's done by the engine management feeding a PWM signal to the 'smart' alternator - the pulse width determining the charge rate. This allows the ECM to make the alternator 'charge hard' when coasting to provide a very primitive form of regenerative braking.

You're missing the point of what I'm saying, I'm not saying the alternator doesn't charge the battery, I'm saying it only provides a surface charge - it's not sufficiently deep to ensure the start/stop will work properly if the battery wasn't slow charged sufficiently in the initially.
 
The dealer had the car yesterday to try and pin down the problem.
I suggested the gear lever sensor as other symptoms have developed.

Sometimes when stopped with the motor off (start/stop turned the motor off that is) I was getting "press the clutch" on the display. This to me meant that the car wanted to re-start but thought the car was in gear so wouldn't turn the starter motor. A quick wiggle of the gear stick and it'd fire up.

They found the neutral gear sensor out of tolerance or alignment (whatever they said) and have adjusted it. No fault codes were strored on the ecu.

I have the car back and all seems fine so far. Time will tell.

They loaned me a new Panda Lounge which I really liked. If you're interested in how I got on with it, you can read about that Here
 
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