Technical Engine stalling

[Mypanda12]

Hi all, hope someone can help, I have just registered on this forum to help diagnose what is wrong with my Mums fiat Panda 2009. The issue is that it appears to intermittently stall, but strangely it seems only when the temp needle is below half way, so it runs fine when engine is warm. Starting from cold is no problem but after 4-5 mins of driving is often stalls. The battery is good.

My mum took it to garage and they checked it out, said it was a cambelt issue, so they replaced that (It likely did need replacing anyway as its done over 90K miles), and said its running fine and gave it back, but the issue persists. Then my Brother took it to another garage and asked them to clean out the throttle body, as someone told him that would fix the issue, but the issue still persists. Yesterday I replaced all the spark plugs, and all the HT leads, checked the two coil packs with a multimeter (both reading within spec), but again the issue still persists. The EML is not flashing up, and a quick scan with my cheapish reader reveals no pending codes, although there is x1 stored code (PO115,Engine Coolant Temperature (ECT) Sensor Circuit Malfunction).

Anyone have any ideas ? So far we have

Replaced cambelt (garage used a cambelt kit)
Cleaned soot from inlet manifold
Replaced Spark plugs
Replaced HT spark plug leads
Checked both the coil packs primary & secondary resistances (both readings are within spec)

Thanks for any help, the garages can find nothing wrong !!

 

[koalar]

Are we talking

Cut out but restarts fine

Cuts out while diving along at speed

Or only stalling at junctions at idle

There quite I few common issues that can be checked without changing parts

The simplest first step.is to remove the MAP sensor and inspect it for oil, it's only one bolt, you can leave the electrical wire connected

Is your car cable or electronic throttle


Also post a picture of the of the old plugs

 

[Mypanda12]

Thanks for reply Kolar, I should note first that the car is in fact a Mk 2 !! (posted in wrong sub-forum)

So, yes it does restart after stalling. It appears to stall only when coming to a stop or driving slowly; its fine on the motorway at speed !
The throttle is a cable type.

 

[koalar]

Thanks for reply Kolar, I should note first that the car is in fact a Mk 2 !! (posted in wrong sub-forum)

So, yes it does restart after stalling. It appears to stall only when coming to a stop or driving slowly; its fine on the motorway at speed !

Unlikely to be the crank sensor they fail when hot

It's usually fairly random and usually difficult to restart

Its fairly easy to spot on car with a rev count as it's on zero before the engine fully stops

Start with looking at the MAP

It's on the black intake manifold

Electronic throttle left side, cable throttle right side if facing the engine

1x torch bolt

Not sure about the cable but the electronic throttle you can get to without removing the air box

 

[Mypanda12]

Thanks Koala, I will post some pics of the removed spark plugs (need to dry them with hairdryer as they been in the bin outside overnight). I will definitely take a look at the MAP sensor ? Will cleaning it suffice, or should I replace ? This stalling issue appears to only persist when the engine has not fully warmed up; for example yesterday my Brother started it and left it running for 1/2 hour, then took it for a drive and it was fine. He then left it for about 5 hours, started it and set off with the engine cold and the issue persists. We think its temperature related somehow, although who knows ???

 

[koalar]

Thanks Koala, I will post some pics of the removed spark plugs (need to dry them with hairdryer as they been in the bin outside overnight). I will definitely take a look at the MAP sensor ? Will cleaning it suffice, or should I replace ? This stalling issue appears to only persist when the engine has not fully warmed up; for example yesterday my Brother started it and left it running for 1/2 hour, then took it for a drive and it was fine. He then left it for about 5 hours, started it and set off with the engine cold and the issue persists. We think its temperature related somehow, although who knows ???

If it's oil fouled clean is fine

Point it noise down and spray with carb or brake cleaner

Push a strip of cloth through the hole to remove any excess

Depending on whether it's cable or electronic, the electronic ones require a long screwdriver or similar as it sits at the end of a long tube

 

[Mypanda12]

Thanks will do that tomorrow when its light. The throttle is the cable type, not electronic. Here is some pics of the spark plugs, do these pics reveal anything ?? Thanks again its really helpful

!

 

[koalar]

All 4 plugs are rich, it's over fueling

You have a scan tool so we can see if the ltft and stft are in the positive to see if the ECU is adding fuel

But that's latter, after we seen if the MAP improves things


Second from right looks to have a small gap, is that the camera angle

 

[Mypanda12]

All 4 plugs are rich, it's over fueling

You have a scan tool so we can see if the ltft and stft are in the positive to see if the ECU is adding fuel

But that's latter, after we seen if the MAP improves things


Second from right looks to have a small gap, is that the camera angle

Yep its the camera angle, they all have the same gap, and I agree they all look a bit sooty. The ltft & stft is lost on me but can investigate further if needed, thanks for the info. Anyhow not to dismiss your time and efforts in responding; I have read online that stalling can be caused:

"because the Engine Control Unit (ECU) receives a faulty "cold" signal, causing it to incorrectly adjust the fuel mixture (over-fueling) or trigger a safety shutdown."

and that this could be caused by either a "stuck open thermostat" (unlikely as car is not overheating), "Faulty coolant temperature sensor" (would this not enable the EML light ?), "Corroded wiring or earth strap" (possibly, will take a look at the earth strap tomorrow), "Air locks in the cooling system: That causes the gauge to fluctuate wildly (gauge is not wildly fluctuating). So my reasoning rules out 3 of those 4, leaving only the wiring issue (I really hope its not a wiring issue).

But, I will check the MAP sensor tomorrow as advised and hope it is just that. I will keep the post updated in any case !!

 

[koalar]

Faulty thermostat on these is fairly common
I never know them to cause stalling
It will over fuel

You should see the car struggling to get half way, should be in the middle within about 3 miles or so along as the cabin fan is only on 1 or 2 setting



It's fairly easy to test the thermostat from cold

common problem with thermostate | FIAT Panda (Mk3)

when the weather get cold we get loads of cooling issues heaters only blowing warm P0115 error radiator fans coming on fast. gauge dropping down occationly. gauge only going up 1/4 way 90% are down to a missing rubber gasket inside the thermostat. Because the thermostat is opening and...

www.fiatforum.com

But start on the most important

 

[Mypanda12]

But start on the most important

Yep will do, thanks again

 

[Mypanda12]

Hi again. I cleaned the MAP sensor this afternoon, unfortunately It has not solved the issue, its still stalling regularly when engine is cold. I did notice that when restarting from a stall it is not instant like I originally suspected, it takes around 5-10 secs or cranking. I'm convinced its a temperature related as the appears to run fine when warmed up, and similarly if the revs are high when its cold. Would anyone consider it could be an issue with the coolant temperature sensor perhaps ?

 

[koalar]

Hi again. I cleaned the MAP sensor this afternoon, unfortunately It has not solved the issue, its still stalling regularly when engine is cold. I did notice that when restarting from a stall it is not instant like I originally suspected, it takes around 5-10 secs or cranking. I'm convinced its a temperature related as the appears to run fine when warmed up, and similarly if the revs are high when its cold. Would anyone consider it could be an issue with the coolant temperature sensor perhaps ?

Unlikely unless it a really wild reading

It runs the temperature gauge as well what's that look like

You've got a scan tool

What the live data from the throttle pedal look like. Is it steady. And smooth when pressing the pedal down

What's the coolant sensor looks like

What the actual rpm look like compared to expected

Whats the long term fuel trims look like

 

[Mypanda12]

The temperature gauge looks to be operating normally. The coolant sensor I have not yet looked at. RPM sounds normal when it is running. The scan tool I have is just a code reader and even if I did have a proper scan tool with live data readings it would be lost on me. In a nutshell Im trying to diagnose likely culprits and to change them myself rather than take it to another garage for them to not fix the issue and charge me ££££ in the process (which has happened twice now). The car does not overheat ever, and the temp gauge on dash looks normal when it is running. The thing is if I start it, go indoors, have a cup of tea and leave it running for 1/2 hour, it then drives around fine. But if I start it, warm it for a minute and then drive it will stall just up the road.

 

[koalar]

Without any data to go on

It's would be pure guessing

You might get it right fist time or 10th time

It starts to add up

The only thing we know so far is it's running very rich and it stalls when cold

Like I said earlier there's many possible causes

MAP sensor
Head gasket
Intake to cylinder head leak
Battery, already changed
ECU
Throttle pedal
Throttle body
Faulty wiring
Evap stuck open
O2 sensor
And so on

And a long list isn't very helpful to you


While cold you could try this test

Koalar random thoughts | FIAT Panda (Mk3)

Got the car here for a few day 1.2 petrol 2011 Going to post a few pictures and video of some simple and basic tests My well be a bit random as they pop into my head and might sort them into the proper order later

www.fiatforum.com

What's the car sound like when cold,.More often than not when the plug are that sorted there's been a misfire causing the fuel trims to go way positive

A cheap £5 elm327 and android phone would tell us if this was the case

 

[Mypanda12]

Thanks Koala, yes now you put it like that it starts to add up. The car sounds just fine when cold, at least to my ears, no noticeable miss firing, it purrs as it usually did; sounded even finer when the plugs were changed. I will have a look at the linked post and try to digest it. If all else fails will have to get it towed to a bonafide Fiat garage and get them to sort it. BTW what is an EVAP ?

 

[koalar]

Thanks Koala, yes now you put it like that it starts to add up. The car sounds just fine when cold, at least to my ears, no noticeable miss firing, it purrs as it usually did; sounded even finer when the plugs were changed. I will have a look at the linked post and try to digest it. If all else fails will have to get it towed to a bonafide Fiat garage and get them to sort it. BTW what is an EVAP ?

There's a charcoal canister in the back that captures the fuel vapour, there's a valve (solenoid) on the intake that should only let the vapours enter when the engine is hot and the throttle is partially open

It's not unknown for them to stick open, A bead from the canister gets sucked into it and jams


It's easy to check. I have a video on it, let's get the inlet out of the way first


Just take the air box off, at idle if you place you hand over the.throttle body, it should get sucked down really hard, the engine stop immediately and the vacuum maintained for a few seconds

 

[Mypanda12]

It's easy to check. I have a video on it, let's get the inlet out of the way first


Just take the air box off, at idle if you place you hand over the.throttle body, it should get sucked down really hard, the engine stop immediately and the vacuum maintained for a few seconds

Great will try that tomorrow, the throttle body is under the airbox, its round with the butterfly valve ? Is that correct? If I put my hand over it and engine does not stop it means there's a leak ?

 

[koalar]

Great will try that tomorrow, the throttle body is under the airbox, its round with the butterfly valve ? Is that correct? If I put my hand over it and engine does not stop it means there's a leak ?

Correct

There a video in the link if me doing the test

Obvious to be of any use it has to be while it's failing

So straight after startup

My gut say it will.not be this, it does cause idle issues, normally there's also some hunting up and down as well,

As it's free to test and quick to test it worth doing

Evap is free to test also but get this out of the way

 

[Mypanda12]

Thanks will keep you posted