Technical Stop Start Story

[UFI]

Is the car clever enough to monitor temperatures and disengage SS until the turbo has cooled down? Apparently, but I don't really want to find out.

I've never seen turbo temp as a S/S parameter. In fact, few if any ECU's directly monitor turbo temps.

 

[306maxi]

I really don't feel that turbo's and start and stop are an issue, turbo tech has moved on since the 80's and 90's. Plus you're going to coast coming up to lights which will give the turbo time to spool down.

 

[Mick F]

Just a small update to my "story".

New battery arrived this morning.
It should have arrived yesterday, but the delivery driver couldn't find us.
Satnav?

Any road up, it's now on charge and when fully up, I'll let it rest for a couple of hours then fit it and go for a ride.

The car hasn't been driven for nearly 48hrs and the the old battery is now reading 11.7volts.

Fingers crossed for the new battery,
Mick.

You can all uncross your fingers.

Stop/Start works perfectly!

New battery was actually charged ok on delivery, so it took just over an hour for the battery charger to register "charged". I let it rest an hour, then removed the old battery, cleaned up the tray area, dropped the new one in and tightened the strap.

I took the old battery indoors and connected up the charger, then connected up the new battery and reset the date/time, then went and had a cup of tea.

Maybe two hours after connecting up, I started the car ....... WOW! ...... the engine nearly took off and bust into life with a flourish!

First time at traffic lights is only half a mile from home and nothing happened, but the next junction at 5miles the S/S came in but I wasn't long enough stopped to test it out. Later, I found a quiet spot and tested it.

Easily 2.5mins, maybe more, and when it started automatically, the ventilation fan came on quite full. We have the ACC set to 24degC. Maybe the S/S aborted due to the ACC taking precedence.

Old battery is STILL on charge and nowhere near being right even after maybe three hours.

Whatever ............ this is a success story.

Thanks guys, you can all relax now.
Mick.

 

[AndyRKett]

You leave it in gear with your foot on clutch at a red light?
My mrs. does that- in her car I just sit there and say nothing.
If it's my car she's driving she knows not to by now, but usually forgets and I have to gently remind her she's wearing my clutch out.

As jrkitching points out it will wear the thrust bearing but not the clutch, also this isn't a long term car for us and will be updated n a year or so's time in the mean time it's covered under waranty, so I'm really not worried, especially as most of our driving is long distance and rural.
I'm more worried about my missus plowing it into something like she did the last one

 

[UFI]

I really don't feel that turbo's and start and stop are an issue, turbo tech has moved on since the 80's and 90's. Plus you're going to coast coming up to lights which will give the turbo time to spool down.

My mechanic is still doing well replacing turbos at low miles on city driven cars. By the mid 80's most turbos were intercooled and running synthetic oils. I don't know that the tech has changed much since.

 

[AndyRKett]

My mechanic is still doing well replacing turbos at low miles on city driven cars. By the mid 80's most turbos were intercooled and running synthetic oils. I don't know that the tech has changed much since.

Higher engineering tolerances, better materials, computer modelling and design, electronic management and control, variable geometry, and electronic bypass valves, turbo technology has moved on a lot since the 80s

The essence of how a turbo works might not have changed much, but there is little in common between a modern turbo and their 80s counter part

 

[jrkitching]

You can all uncross your fingers.

Told you .

The car hasn't been driven for nearly 48hrs and the the old battery is now reading 11.7volts.

Says it all really.

You might require sophisticated equipment to test a S/S battery on the spot, but if you don't mind waiting 48hrs, a cheap digital voltmeter may be all you need.

Amazing that so many independent folks had tested your old battery and said it was fine, even though some of them would have had a vested interest in selling you a new one.

 

[Mick F]

Yep, that's another one to chalk up!
You should keep a log.

I have been thinking today to go back to the two places who tested the old battery for me and trying to explain ............... but I think they wouldn't understand.

Thanks for letting me harp on about this. I get a bit obsessive and single-minded about things.

Thanks and regards,
Mick.

 

[Mick F]

PS:
I may take a stopwatch next time out and turn various things on and off over a series of tests .................. but that's being a bit TOO obsessive.

Ta,
Mick

 

[jrkitching]

Thanks for letting me harp on about this. I get a bit obsessive and single-minded about things.

You're not the only one on this forum .

It keeps things interesting .

 

[UFI]

Higher engineering tolerances, better materials, computer modelling and design, electronic management and control, variable geometry, and electronic bypass valves, turbo technology has moved on a lot since the 80s

The essence of how a turbo works might not have changed much, but there is little in common between a modern turbo and their 80s counter part

90% of the development of the turbo has been to reduce lag, therefore it works harder more of the time. In the 80's you were lucky to see any boost before 2500rpm. Most cars now produce boost from just above idle.

No matter how slowly you're driving you're on boost. The time it takes to stop at a red light might not be enough for it to cool.

Do a google, BMW, VW, Citroen etc still fail at extremely low milages.

 

[Piccolo Nero e Bella]

You can all uncross your fingers.

Stop/Start works perfectly!

Thanks guys, you can all relax now.
Mick.

Phew!!

 

[306maxi]

Do a google, BMW, VW, Citroen etc still fail at extremely low milages.

Why do they fail though?

 

[AndyRKett]

90% of the development of the turbo has been to reduce lag, therefore it works harder more of the time. In the 80's you were lucky to see any boost before 2500rpm. Most cars now produce boost from just above idle.

Hang on one minute you say there's been no developments since the 80s the next you have a whole list of improvements...... Make your mind up

 

[jrkitching]

Why do they fail though?

Quite often because the bearings overheat once the oil circulation stops.

The only foolproof way around this (if you want to stop the engine before the turbine core has cooled down) that I can see is to fit a second, electrically operated, oil pump with a delay timer.

But that's the view of an engineer rather than the view of someone in marketing/accounting. Adding a second oil pump would also add cost.

Car manufacturers will sometimes put achieving the right headline numbers ahead of long term reliability.

 

[UFI]

Hang on one minute you say there's been no developments since the 80s the next you have a whole list of improvements...... Make your mind up

These developments are irrelevant to the discussion of reliability of S/S equipped Fiats, hence why they were left out a minute ago....until someone decided to drag VGT's into this.

Bearings still fail on hot turbos just like they did in 1975.

 

[306maxi]

Back then oil was crap and yes, if a turbo was red hot and you turned the engine off then it would coke up, a lot less likely to happen now imho.

 

[AndyRKett]

These developments are irrelevant to the discussion of reliability of S/S equipped Fiats, hence why they were left out a minute ago....until someone decided to drag VGT's into this.

Bearings still fail on hot turbos just like they did in 1975.

Maxi stated that technology had moved on so didn't see that S/S was going to be much of an issue to a modern turbo.

You stated that technology hadn't changed since the 80s....

The example given were of how technology had moved on since the 80s including VGTs but also materials, design, tolerances and electronic control.

Look see!



The improvements in materials, tolerances and design means that bearings are far less likely to fail on a modern turbo, than they are on a unit from the 80s, this is the sort of thing I suspect Maxi was getting at, VGTs was just an example of how turbo technology had moved on, where you were claiming it hadn't.

In the 80s turbos were fitted to only special cars where as now with the huge growth in demand for turbo diesel cars and manufacturers pushing down the co2 outputs of all models, virtually all cars on the forecourts today come with at least one turbo engined option. As a result of course you will see higher numbers of turbos failing, from all manufactures

 

[jrkitching]

Back then oil was crap and yes, if a turbo was red hot and you turned the engine off then it would coke up, a lot less likely to happen now imho.

Synthetic oils certainly have better temperature stability and carbonization resistance than mineral oils.

My own personal take on this:

Do I believe that the thermal cycling caused by repeatedly shutting down & restarting a car with a hot turbine will shorten its life? Yes.

Is this likely to affect owners during the projected lifespan of the car? Who knows. However much testing Fiat have done, noone can say for sure until the fleet has some real age on it. IIRC a lot of early TA's were recalled for turbo replacement.

Would I buy a turbo equipped car with S/S? No. But then I'm a conservative type who generally keeps cars a long while.

Is this relevant to the majority of new car buyers who will be trading in after three years or so? Probably not.

Should used car buyers be concerned? I would be. Second & subsequent owners are generally much more concerned about out-of-warranty repair costs than new car buyers. Interestingly Parkers guide prices for used TA's are slightly lower than for the equivalent 1.2's, despite the TA having a price premium when new.

 

[Most Easterly Pandas]

Synthetic oils certainly have better temperature stability and carbonization resistance than mineral oils.

My own personal take on this:

Do I believe that the thermal cycling caused by repeatedly shutting down & restarting a car with a hot turbine will shorten its life? Yes.

Is this likely to affect owners during the projected lifespan of the car? Who knows. However much testing Fiat have done, noone can say for sure until the fleet has some real age on it. IIRC a lot of early TA's were recalled for turbo replacement.

Would I buy a turbo equipped car with S/S? No. But then I'm a conservative type who generally keeps cars a long while.

Is this relevant to the majority of new car buyers who will be trading in after three years or so? Probably not.

Should used car buyers be concerned? I would be. Second & subsequent owners are generally much more concerned about out-of-warranty repair costs than new car buyers. Interestingly Parkers guide prices for used TA's are slightly lower than for the equivalent 1.2's, despite the TA having a price premium when new.

Couldn't have put it all better myself