Technical Intermittent misfire with no fault codes

[Janeylou]

Hi
My other half has a 2014 500 1.2 which has developed an intermittent misfire which causes the eml to flash and the triangle light to illuminate.
It's done it twice now and there is no said pattern to it.its happened at a roundabout and going downhill.
normally the car runs perfectly with no faults .if you switch off and restart,it's perfect again.
Very strange.its had new leads and coil pack and plugs,a crank sensor but it's happened again today with no fault codes recorded.
Naturally she's loosing faith in what is her pride and joy.

Anybody else come across this or similar?

 

[John202020]

Next time it happens see if the light actually flashes a code? like say 3 short, pause etc?
Its odd there's no code however are you using Fiat specific software to read the system not a generic code reader?

 

[varesecrazy]

Hi
My other half has a 2014 500 1.2 which has developed an intermittent misfire which causes the eml to flash and the triangle light to illuminate.
It's done it twice now and there is no said pattern to it.its happened at a roundabout and going downhill.
normally the car runs perfectly with no faults .if you switch off and restart,it's perfect again.
Very strange.its had new leads and coil pack and plugs,a crank sensor but it's happened again today with no fault codes recorded.
Naturally she's loosing faith in what is her pride and joy.

Anybody else come across this or similar?

Hi.
How frustrating..

If it is the original bettery.. then that could be contributing.

Our (non.stop:start) panda stopped completely.. no codes (on full FIAT Diagnostic kit..)

So a new battery was fitted.. zero issues in the years since.

Modern vehicles need a perfect electrical supply.. a tired battery can have problems meeting that need.

Charlie

 

[wardpaa]

Check earthing strap to battery and strap underneath battery tray.
As there are no recorded p codes it could be fuel delivery related (pump/relay) so worth checking that too.
It's difficult to pin point intermittent faults like these as you can end up changing parts unnecessarily.

 

[Janeylou]

Hi again,
Thanks for the suggestions.
It's had 3 different code readers on it, a basic handheld job, a pc based more professional reader and a specific fiat reader but all show no codes recorded and no pending faults either.
Battery seems ok ,it has no problems starting even after leaving lights ,blower etc on for a little while.we are thinking of replacing it anyway as it is the original and we live up a Welsh mountain so may be prudent!
Earths have been cleaned and checked today.
Car started from cold instantly this morning and sounds fine.it is frustrating as you can't fix what you can't see.

 

[John202020]

Faulty ecu ? It's the only reason I can think of why it's not registering fault codes?

 

[Goudrons]

Faulty ecu ? It's the only reason I can think of why it's not registering fault codes?

It depends on what is happening with what.

Some faults need to occur three or more times in one drive cycle before they get logged and then may only soft code/pend for them to then clear again on restart.

This makes intermittent problems like this a nightmare to diagnose, particularly if the drive cycle is short (short trips) as it's not repeating enough to record the fault properly.

You could drive around and log the codes, but you'll probably just pick up the misfire (the flashing EML) rather than what's causing it.

The yellow warning triangle is a generic warning, it relates to the following: Oil Change Request, Engine Oil Pressure Sensor Failure, External Light Failure, Fuel Cut-Off Not Available, Parking Sensor Failure, DST System Failure.
I would hazard a guess the misfire is interrupting one of the above's circuits, perhaps the power to the DST (electric power steering) .


You are probably best to try and find a proper diagnostic expert that can run the car around and log all the sensors (and knows what to look for).

A dealer will only do what you have already done and then move on to swapping out parts in hope (and charging you for them) until they hit the right one.

 

[Eklipze3k]

Check earthing strap to battery and strap underneath battery tray.
As there are no recorded p codes it could be fuel delivery related (pump/relay) so worth checking that too.
It's difficult to pin point intermittent faults like these as you can end up changing parts unnecessarily.

Bad earth was going to be my suggestion too, definitely worth checking as it'll cost you nothing.

 

[varesecrazy]

Bad earth was going to be my suggestion too, definitely worth checking as it'll cost you nothing.

To be honest.. my money is stil on the battery..

but the main earth breaking down is also a common occurence..
No end of terminal cleaning will fix an internal cable fracture..

 

[varesecrazy]

Battery seems ok ,it has no problems starting even after leaving lights ,blower etc on for a little while.we are thinking of replacing it anyway as it is the original and we live up a Welsh mountain so may be prudent!
Earths have been cleaned and checked today.
[/QUOTE]
Janeylou

If you are on MY mountain.. I would offer a push..

Have a read of GRANDE PUNTO FAQs for lots more electrical gremlin info.. yellow triangle related

Charlie . Abertillery

 

[John202020]

But the main earth breaking down is also a common occurence..
No end of terminal cleaning will fix an internal fracture

If replacing with non OEM its 250mm long with 8mm holes in at each end. Think I got 25mm2 size for £3 on Ebay

 

[Janeylou]

Thanks to you all, update at the moment car runs perfect with no repeat of the misfire.it regularly does short runs,15 mile or so but has done a couple of 200+mile runs since the first occurance of the misfire.
I agree a dealer would go for the suck it and see approach as nothing is showing up as a fault.
Wouldn't it be nice to get back to good old plugs and points days that you could actually repair!
The earth lead makes sense and for what it'll cost will be done.