Technical The incurable Punto 'stalling issue'........

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Technical The incurable Punto 'stalling issue'........

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May 3, 2019
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Lowestoft,Suffolk
Hiya guys-n-gals.

Joined up to see if i could get some info with a hugely annoying problem. Should have done so earlier....as we have 2 Punto's in the house; and being a Petrol-head - i'm always up for some car related chat / banter....



So my sons 2008 1.2 Punto 'Dub' recently started randomly stalling. It 200% worse when hot. And if pulling up to a junction for example and depressing the clutch - will stall 50% of the time. And 100% if / when you press the brake pedal irrespective of anything else ! Will do this even stationary.

Car went into my normal garage of 30 years and a crank / RPM sensor fault was showing - so was replaced with new. No better - so they suggested a cam sensor. Genuine Magneti Marrelli item fitted. No better. Garage then says they've had enough........:bang: [Which annoyed me hugely as all work was paid for; but they pretty much just 'gave up' as this point]

Next garage thinks its fuel pump and is sure he can hear it cutting out. Takes it out, cleans it etc - refits as can't get a new unit in the same day - then decides it's not the pump after all. Tries everything they can think off - but when car is warm - even when sitting stationary - just pressing / pumping the brake pedal a few time and off the car goes. Needle just drops below 1k, carries on sweeping down until it stalls.

They then played around with the brake servo / vacuum hoses, disconnected the MAP sensor, tried a brand new MAP sensor all to no avail.

When car is cold it drives, starts and sounds faultless. Even so when warm until you nearly come to a halt. At this point we're all scratching our heads.

Their suggestion is possible internal brake servo fault causing vacuum issues.
Possible throttle body issue.
Maybe even an ECU fault.


But the car has and throws out no ECU fault codes so really unsure where to even begin ??



Suggestions welcome as my newly driving sons confidence is getting low !

Cheers all.
 

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Welcome to the forum :)

I had something similar happening on my old Seicento, was a split vacuum hose which was only apparent when the engine temperature rose and the hose became malleable enough to allow air out of the split.
A split hose somewhere would be my first thought, followed by some kind of issue with the brake servo.
I see that a garage had a fiddle with some of the hoses, but short of taking them off and leak testing them it'd be pretty hard to pin it down with just a fiddle.
 
Welcome to the forum :)

I had something similar happening on my old Seicento, was a split vacuum hose which was only apparent when the engine temperature rose and the hose became malleable enough to allow air out of the split.
A split hose somewhere would be my first thought, followed by some kind of issue with the brake servo.
I see that a garage had a fiddle with some of the hoses, but short of taking them off and leak testing them it'd be pretty hard to pin it down with just a fiddle.

Thanks for the Welcome Eklipze3k ! And the fast response.

They found a split breather hose, and a split vacuum hose. Both were replaced. Neither made any noticeable difference.

They THINK there's an internal leak in the servo. But say you can usually hear this / notice a hissing noise (Not specific to Punto's) to confirm. With this car - nothing. Both the garage owner and the supposed 'very clever' mechanic working on the car are both headed toward thinking its a servo fault - but are loathed to keep chucking our money at it 'willy nilly' when nothing seems certain / obvious as such.......

But we need to try something ?? !!
 
The car had an inner wing missing on passenger side when we bought it. Externally the brake servo isn't good and 'very' corroded. Does it have a pin-prick etc in etc no-one knows about......or infact an internal fault ? I think for what it's worth - it would be a good idea to try another one on the car, as irrespective of anything else whenever the pedal is depressed the fault occurs - so is clearly brake related in some form. And nothing else is showing up as faulty.

How do i tell if a 2008 1.2 Dub 8v has ABS or not. So i know if i'm buying the correct servo ?
 
Hi 'Shuv' and welcome on board.

You can temporarily condemn the servo by pinching the vacuum hose that comes either from the manifold for a petrol car or from the vacuum pump for a diesel engine. Be aware though that the brakes will then be VERY hard to actuate, don't let your Son drive the car in this configuration!

What engine is your car?

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)
 
Hi 'Shuv' and welcome on board.

You can temporarily condemn the servo by pinching the vacuum hose that comes either from the manifold for a petrol car or from the vacuum pump for a diesel engine. Be aware though that the brakes will then be VERY hard to actuate, don't let your Son drive the car in this configuration!

What engine is your car?

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)


Morning Bernie,

I'm positive the garage did just what you're describing. The issue being the pedal became so hard; it couldn't then be pumped a few times to get the vacuum drop and replicate the stalling fault......

The engine is my sons car is a 1.2 8V.

Cheers.
 
Just found this elsewhere on this site.........

"If the engine will tick over happily when stationary, but then dies if the brakes are pressed, this points at an air leak in the servo. The hose from engine to servo is probably ok as this would cause running problems all the time. Likely the servo diaphragm is split, or might just be the valving. You need a diagram of the inner workings, or a servo rebuild specialist, or a complete rebuild kit if you are competent to rebuild it yourself."

I've now orded a servo. Will update :)
 
Morning Bernie,

I'm positive the garage did just what you're describing. The issue being the pedal became so hard; it couldn't then be pumped a few times to get the vacuum drop and replicate the stalling fault......

The engine is my sons car is a 1.2 8V.

Cheers.


seems pretty obvious then that the servo is leaky... Hard pedal was expected too!

BRs, Bernie
 
seems pretty obvious then that the servo is leaky... Hard pedal was expected too!

BRs, Bernie

So: current / original servo has smoke ‘leak through it’ when smoke tested. This looked suspect.

So supposed tested, warranted servo bought with thought of replacing. This was smoke tested too before fitting and again leaked. Suspect replacement unit is the first thought of course...

So to be sure - I then bring my wife’s perfectly working 13 plate 1.4 Punto in to the garage today - and lo and behold : when we smoke test her servo....it also “leaks’ back into the cabin.

So all 3 servos show this trait. Which in itself is very unusual on any car I gather !!!!???? But is of course happening with all 3 Punto servos.

Garage has suggested ABS pump or throttle body. But Is truthfully flummoxed.

Not sure throttle body has any effect on a car stalling when brake is applied - so my brain says a logical step would be to try a new ABS pump.

Thoughts please !!
 
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This is a huge longshot but here goes,

You mentioned earlier that the clutch pedal gets or got to hard to press, at this point, did you try opening the slave bleeder to see if the pedal would then drop to the floor?

I actually don't have a manual Punto but if the clutch is using the fluid from the brake master cylinder, maybe there is a blockage or air in the line,

Also if all three of your Punto's servos have the same traits as one another, you might be able to rule them out, since your wife's Punto is going well,

Have you tried pumping the the brake pedal before you turn the car on? Does it get hard to press after 3 or 4 goes?

Then maybe bleed brakes all round, make sure no air or blockage in each line,

Or if the car is driveable and the clutch and gear changing are working well, the abs pump might be the problem, have you tried unplugging the abs module and the battery for a while? Try to do a kinda soft reset,

Like I said, bit of a longshot
 
Also maybe someone on the forum has done a leak test on their servo,
I actually haven't,
So anyone, let us know your results....
 
This is a huge longshot but here goes,

You mentioned earlier that the clutch pedal gets or got to hard to press, at this point, did you try opening the slave bleeder to see if the pedal would then drop to the floor?

I actually don't have a manual Punto but if the clutch is using the fluid from the brake master cylinder, maybe there is a blockage or air in the line,

Also if all three of your Punto's servos have the same traits as one another, you might be able to rule them out, since your wife's Punto is going well,

Have you tried pumping the the brake pedal before you turn the car on? Does it get hard to press after 3 or 4 goes?

Then maybe bleed brakes all round, make sure no air or blockage in each line,

Or if the car is driveable and the clutch and gear changing are working well, the abs pump might be the problem, have you tried unplugging the abs module and the battery for a while? Try to do a kinda soft reset,

Like I said, bit of a longshot


Firstly - THANKS for your thoughts. All shared knowledge and experience at this point is awesome !

I said brake pedal (as expected) got hard [Not clutch pedal] when vacuum pipe was disconnected in order to test. All i meant was - unfortunately at this point brakes were so hard pedal-wise; it was impossible to pump them at tickover and get the car to stall. Which it was doing with servo connected.

***I've just been out to car and pumped pedal a few times with car off. And yes - brake pedal did get rock-hard after those few pumps.

Soft-reset sounds a good idea. I'll disconnect ABS module and battery and leave off Sat night. Might be interesting for sure !

Thanks again buddy.

***Where in the World are you ???
 
If all 3 are doing the same thing then in all honesty it seems like a inconclusive test, I would swap it but then again I'd be doing it myself and not paying garage prices ;)

My son is 17 and on minimum wage (£6.15) an hour.

As much as i don't want him to think cars run for free - i also don't want him to chuck £££££ at a seriously un-diagnosed problem if we can at least get some sort of direction to head in.

Garage have been awesome so far helping him out. But they are flummoxed and so am i. May well have to start 'chucking bits on' soon though......

So its either going to have to be servo (Which to me is 'unlikely' seeing as all 3 give same results from smoke test), throttle body: Not sure why it might be this - and why it would effect the car when the brake is pressed at tickover ?, or ABS pump. Which would be my initial first try right now......


Cheers my friend.
 
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