Technical newbie with a lumpy rough running fiat 500 lounge 2014

[Scalex]

Hi folks,
I've had a Panda 1.2 2005 for the last 10 years, and never had a problem, so buying my daughter (ok she co-funded it) a fiat 500 2014 Lounge 1.2 seemed like a good idea...

Problem is that since the cold weather, it's been playing up and still has a problem, so could really do with some help. I've read the post about a lumpy 500 at idle. My 500 symptoms seem similar but it also is lumpy/hesistant especially at lower speeds.

Car has done 60000 miles

About a month ago:
Car starts fine, sounds ok.
However, after the car has been driven about 1/2 mile, sudden loss of power, can hardly keep going and very juddery. After about 1/2 mile further, problem goes away and car starts to run much better, but still not perfect
Given the car is 9 years old, and winter is on us it made sense to get a new battery fitted which I did.
This seemed to really help, but still some loss of power, but not as bad.
Connected an OBD II scanner, cleared all codes, then went out. Got Fault P0300 and P0304 - cylinder 4. Great news I thought. We know where the problem is.
So, reading online, possibilities are spark plugs or coil pack. To be safe, I changed the spark plugs and coil pack at the same time yesterday.
Today, my daughter took the car for a long drive, 70 miles round trip. No sudden loss of power, but still very lumpy. No fault codes.
Car drives much better at speed - 50mph plus. but stutters on slowdown.
At idle it seems to have a stutter every few seconds

So car has had new battery, new coil pack, new spark plugs (all from euro car parts, not 2nd hand)

I've just added Wynns Injector cleaner and will see if this helps, but what are the next steps?

one question - Should I need to adjust the spark plug gap?

My thoughts:
Dirty injectors?

Will reading anything else from the ODB II port help at all? I've just got a generic bluetooth device and phone app, but it can monitor in real-time.

All thoughts appreciated.

I'm an amateur - not professional mechanic - be kind

Cheers

CB

 

[steveras57]

If you have read my posts you will have seen i have had a similar experience! my problems revolved around a very lumpy idle! the car ran fine but the idle was just "wrong" though the taco showed a steady 750 rpm you could feel the "lumpyness" through the seat drove me nuts!.

I did what you have IE-plugs/ leads/ coil pack did nothing! so replacement throttle body/ map sensor/ etc etc Still nothing!- two tankfuls of the highest octane fuel with concentrated injector cleaner had no effect!.

In the end i bought a used manifold with all components on it and just at random decided to swap the injector rail over( in the end i didnt because its difficult to separate the "quick release fitting" without breaking it!) but i did swap all the injectors over!.
The second i started it afterwards i knew it was cured!- ticked over lovely with no vibes through the seat!.

I know this is not exactly your issue but i would urge you to try changing the injectors as my experience showed that trying to clean them often does not work!.
Id go with swapping the one for cylinder number 4 first! but a full set with the rail is not expensive used!(loads on e-bay for around £30 ) so id by a complete rail so you have a full set of injectors if you need to do them all!.
Hope this helps
best of luck with it!
also might be worth popping the air filter box off and seeing if the throttle body needs a clean!

 

[Scalex]

If you have read my posts you will have seen i have had a similar experience! my problems revolved around a very lumpy idle! the car ran fine but the idle was just "wrong" though the taco showed a steady 750 rpm you could feel the "lumpyness" through the seat drove me nuts!.

I did what you have IE-plugs/ leads/ coil pack did nothing! so replacement throttle body/ map sensor/ etc etc Still nothing!- two tankfuls of the highest octane fuel with concentrated injector cleaner had no effect!.

In the end i bought a used manifold with all components on it and just at random decided to swap the injector rail over( in the end i didnt because its difficult to separate the "quick release fitting" without breaking it!) but i did swap all the injectors over!.
The second i started it afterwards i knew it was cured!- ticked over lovely with no vibes through the seat!.

I know this is not exactly your issue but i would urge you to try changing the injectors as my experience showed that trying to clean them often does not work!.
Id go with swapping the one for cylinder number 4 first! but a full set with the rail is not expensive used!(loads on e-bay for around £30 ) so id by a complete rail so you have a full set of injectors if you need to do them all!.
Hope this helps
best of luck with it!
also might be worth popping the air filter box off and seeing if the throttle body needs a clean!

Hi Steve, really appreciate your reply and suggestions. Definitely want to give it a try. Is changing the injectors any harder than changing the spark plugs? that was straightforward enough. Do I need a special tool? Can't find any decent youtube videos for the 1.2 8V showing how to do it.

My daughter's convinced the problem originally started after filling up at a VERY busy Asda petrol station a couple of months back. Maybe we got some bad fuel.

Cheers
Colin

 

[steveras57]

Hi Colin
Changing the injectors fairly easy for a competent DIY mechanic no special tools just a good tool kit sockets, spanners, screwdrivers,etc
only issue i had was the so called "quick release" fuel pipe -I found the plastic tabs impossible to release by hand and easy to break if you use pliers etc
Id advise leaving it connected and just flexing the pipe out of the way/ backwards to get the injectors out!.
also id get a HAYNES workshop manual online to help you understand the process! best of luck mate
Steve
ps i would have though bad fuel should have passed through the system by now? have the symptoms changed after subsequent re-fuels? by the way i found a distinct improvement in idling system when i fitted IRIDIUM sparkplugs more expensive but last longer so a good idea if you can afford them!

 

[Scalex]

I'm going to give it a try, probs next weekend.

Could an old fuel filter be the problem if the fuel tank has crud it in? My daughter reckons the symptoms are worse when the tank is less than 1/4 full.

Current OBD code showing was P0301, P0300, which I take as cylinder 1 misfire, so I'll change the injector on that one first.

Thanks for your help again, and I'll post back if/when I make any progress,

Cheers

 

[The Panda Nut]

There is no filter excepting at the fuel pump in the tank. I have similar issues periodically with our 2011 1.2 Panda 69hp. It has proved to respond to throttle body cleaning each occasion so far. Although not massively dirty just spraying with carb cleaner seems to do the trick. We suffer with oil accumulation in the manifold via the breather pipes. I also find cleaning the manifold makes a substantail difference to performance and economy. I get clean cotton rag and feed this in with a piece of plastic strip. The MAP sensor lives in the base of the manifold so I dont suppose it takes too well to the oil accuulation. It might just be worth trying this before moving on to more expensive things as there is no cost and it takes just 20 mins. Remove air box. Take care not to break the spiggot for the thinner breather pipe as you do this. Unclip wires and pipes from the the TB and disconnect its wire connector. undo the 4 screws and lift it off. Re-tighten very lightly-- finger tight+ is enough. Careful not to drop bolts or tools down the back of the engine, I lost a spanner down there a while back and its still not turned up.

 

[John202020]

You need the car hooking up to a laptop
Has the engine earth strap been replaced?
Has the cam belt been replaced correctly recently?
Lambda? is ignored for the first 30seconds or so after start?
As the car runs "fine" at first it suggests the injectors are OK?
I feel its a control( fuelling ) issue

 

[varesecrazy]

Nobody has mentioned this..

Look up the "Watchdog thread" On here..

May fit your running issues

 

[John202020]

Replaced plugs and coil pack, what about the leads? Our car had number 4 plug lead fail just after we bought it

 

[Pidge10]

Hi, I am new to the forum, I own 3 500's and I had similar problems with one of mine, I found out it was the top lambda sensor (no code on my multiscan) plus the MAF sensor was playing up.
I started with full service, then coil pack, then injectors to then replace the MAF and Lambda and the car runs like a dream now.

 

[John202020]

If you do replace the Lambda use a quality direct fit one, not a universal one