Technical Revs dropping leading to stall

[WildFeraligatr]

Morning gang - hope you're all well and looking forward to the festive period

I've got a problem with my 2012 model - partner was driving it the other day and told me the oil pressure light came on (yellow) and then the engine cut out. I checked the oil (which was low, in fairness), topped it off and took it for a drive myself. I've noticed that every so often the revs just start dropping - seemed to happen most at idle but when it happened to my partner he said he was driving along around 20mph or so.

- I suspect the oil pressure light came on due to the low revs + low oil so not worried about this - the light hasn't come back on since I've topped off the oil even when revs drop.
- Spark plugs and air filter are both around 6 months old.
- Car has an electronic throttle rather than cable (not sure any of the newer models have a cable!) - I did notice the throttle seems a little stiffer when compared to my '08 Fiat 500 but that could just be differences in the models.
- When the revs dropped when I was driving, I hit the accelerator a bit and it settled back to normal (around 800RPM) so suspect the electronic throttle is okay.
- No engine codes or lights other than the yellow oil pressure light that came on. Car started back up okay after that and seems to be starting okay now.
- Battery is only a few months old, aux belt was replaced in the last year

My suspicion is the fuel pump is on its way out, but I'm going to give the MAP sensor and throttle body a clean as well just to be certain. Just posting here to see if there's anything I've missed at all?

 

[Mike1alike]

Yeap, sounds like throttle body is the issue or the point to start with. It's like it doesn't open enough for idle. Dirt, oxidation take their toll.
It doesn't sound at all like a fuel pump/pressure issue. That acts up on load, on higher revs.
So do clean the throttle body but do a thorough job, like here:

How to clean the potentiometer inside Throttle body

Hi Everybody. I would like to share my experience about the cleaning of the potentiometer inside of the Throttle body. I made this because I fight with bad idle after a big refurbishment and I thought I can try this as well. I had an other...

www.fiatforum.com

 

[koalar]

Take the map off and post a picture before you do anything else

 

[WildFeraligatr]

Yeap, sounds like throttle body is the issue or the point to start with. It's like it doesn't open enough for idle. Dirt, oxidation take their toll.
It doesn't sound at all like a fuel pump/pressure issue. That acts up on load, on higher revs.
So do clean the throttle body but do a thorough job, like here:

How to clean the potentiometer inside Throttle body

Hi Everybody. I would like to share my experience about the cleaning of the potentiometer inside of the Throttle body. I made this because I fight with bad idle after a big refurbishment and I thought I can try this as well. I had an other...

www.fiatforum.com

Will do - and as Koalar said I'll pop the MAP sensor out and send a pic.

The weird thing is that this only happens intermittently - it's not constantly running at 500RPM at idle - is this common with throttle body issues?

 

[Mike1alike]

It kind of is.
Besides the procedure described in the post I put above, I'll do more if possible. Like check if you can take electronic stuff apart from throttle body so nothing gets destroyed and wash the rest of throttle body with warm water + citric acid + laundry detergent. I did that to my cabled TB and the result was amazing. The spring area cleaned like never before (and I tried to clean it with all kind of sprays and stuff) and the throttle flap moves so much easier and smoother. I think that would benefit even more a fly-by TB because on that the flap is moved by that little electric motor so cleaning it like that would totally decrease the load put on that little motor.

 

[koalar]

Will do - and as Koalar said I'll pop the MAP sensor out and send a pic.

The weird thing is that this only happens intermittently - it's not constantly running at 500RPM at idle - is this common with throttle body issues?

Running at 650 instead of 750 is common and

Don't think I seen onr as low as 500

Does the revs rise if you switch all the electrics off, blower and so on

Theirs loads of things it could be, it's a process of test and elimination

2012 are you sure it's a 169 old shape it's right on the cross over of the newer more rounded


Not that it makes much difference as the 1.2L use the same engine

 

[WildFeraligatr]

Running at 650 instead of 750 is common and

Don't think I seen onr as low as 500

Does the revs rise if you switch all the electrics off, blower and so on

Theirs loads of things it could be, it's a process of test and elimination

2012 are you sure it's a 169 old shape it's right on the cross over of the newer more rounded


Not that it makes much difference as the 1.2L use the same engine

It's not constantly running that low - it runs normally at 800 or so, then drops to about 500 - I suspect it will keep dropping and the engine will cut out eventually, but each time I've noticed it I pushed on the throttle a bit and it went back to normal after a bit of revving.

I may have posted in the wrong forum - it's a 319 so yes the newer more rounded model.

 

[koalar]

It's not constantly running that low - it runs normally at 800 or so, then drops to about 500 - I suspect it will keep dropping and the engine will cut out eventually, but each time I've noticed it I pushed on the throttle a bit and it went back to normal after a bit of revving.

I may have posted in the wrong forum - it's a 319 so yes the newer more rounded model.

No problem you can leave it here

Off out but will reply in a couple of hours

 

[WildFeraligatr]

Afternoon gang

I'm finally off work for the holidays so able to go have a tinker

Here is the MAP sensor as requested

 

[koalar]

That's great

Looks to be a problem

Just point the nose down and spray with carb or brake cleaner, it's normally enough

With it being a cable throttle and on the right of the intake manifold if facing the engine

I would undo the bolts holding throttle body and lift it up and clean the pool of oil that "probably underneath


You don't have to remove the wires or anything

 

[WildFeraligatr]

Yep - thought it looked unusually oily. I've just taken the throttle body off and it looks reasonably clean but yes, you're right, some oil underneath.

This is making me wonder where all this oil is coming from and why it's in the intake manifold - that is normal right??

 

[WildFeraligatr]

Throttle body pics for reference

 

[koalar]

Throttle body pics for reference

Push a rag through to the the Map sensor hole

It fills up

The problem is the blow by gass arent being sucked in an burnt properly

Confirm first just disconnect the pipe and see if the problem disappears


We will sort out the reason later once it's been confirmed

 

[WildFeraligatr]

Push a rag through to the the Map sensor hole

It fills up

The problem is the blow by gass arent being sucked in an burnt properly

Confirm first just disconnect the pipe and see if the problem disappears


We will sort out the reason later once it's been confirmed

Which pipe am i taking off sorry?

 

[koalar]

Which pipe am i taking off sorry?

 

[WildFeraligatr]

View attachment 478179

Ah - i popped him off when I got the filter off - the socket it fits on to looks a bit bunged up so I'll give that a clean

 

[koalar]

The blowby gasses are sucked back into the engine to be burnt off

It controlled by vacuum

Depending on throttle opening it is either sucked in under or above the throttle body

It needs to be in good order to work properly

The breather pipe
The grommet under the air box

No leaks or blockages

I had the little pipe completely blocked before now


A quick and dirty test is to remove the pipe so the gasses aren't going back into the intake, if it's fine you know the problem is likely caused by one of the above

Of cause it's not good for the environment to vent into the atmosphere, but to test it's fine

 

[WildFeraligatr]

The blowby gasses are sucked back into the engine to be burnt off

It controlled by vacuum

Depending on throttle opening it is either sucked in under or above the throttle body

It needs to be in good order to work properly

The breather pipe
The grommet under the air box

No leaks or blockages

I had the little pipe completely blocked before now


A quick and dirty test is to remove the pipe so the gasses aren't going back into the intake, if it's fine you know the problem is likely caused by one of the above

If cause it's not good for the environment to vent into the atmosphere, but to test it's fine

Right - well I've given everything a good clean so I'll let my partner run it around for a bit and see if it happens again. If it does then I know what to try next - but it's 4pm on Christmas Eve and I fancy a bit of rest and a drink

Thanks for your help anyway and happy Christmas!

 

[Mike1alike]

This is making me wonder where all this oil is coming from and why it's in the intake manifold - that is normal right?

What happens there usually and leads to so much oil inside intake manifold is the oil channel inside rocker cover gets clogged. So improper lubrication on the upper part of the engine makes some zones there overheated and the oil that touches that burns resulting oil vapors. That is usually accompanied by wear on oil pump pickup gasket that leads to not enough oil delivery so improper lubrication again, this time not just the upper engine side but crankshaft area too. All of that has the result of oil vapors, more than on good working lubrication system engine. Oil vapors are carried inside intake manifold through the crankcase vapor gas recirculation system so intake manifold will always be a little oily. But excess oil vapors due to improper functioning lubrication system makes it very oily.

 

[koalar]

It's only vacuum that pulls the gasses in to be burnt

Any leak is like sucking on a straw with a hole in the side

Known issue fiat take attached below

99% if the time it's nothing more than a blocked pipe or a leak

There's no point in over complicating the issue

Maybe 1 in a thousand is something else