Hi people,

Sorry for the first post being a question but I figured after looking around on the forum I'l have better luck here compared to my local garages!! Here goes,

I currently have a Fiat Grande Punto (2007) 1.2 8v which has been owned from new. Never had any issues until approx 4 months ago where the engine management light intermittently flashes on. Here's the symptoms......

* Only ever happens at speed on the Motorway when its been at the constant speed for a while
* Reader states mis-fire detected on Cylinder 4
* Car feels totally fine, no misfire at all
* Light goes out after taking foot off the accelerator, doesn't come back on after
* Comes on approx once every 3-5000 miles

Car runs totally fine all the time and even when I've not lifted off and purposely kept the engine management light flashing it runs fine.

Any ideas? I don't really want to be taking it a garage who will charge for things that really don't need doing as guesswork!

Has it had the cam belt done recently?

Andy Monty said:

Has it had the cam belt done recently?

Click to expand...

Hi there, thanks for taking the time to reply!

Nope the cambelt has never been changed and I've had a look and it's in decent condition too. Car has only done about 33k and had a full major service last September although this has only started recently. Any ideas?

There is an issue hence the warning light, the ECU has seen cyl 4 at the incorrect time. I would check plug & HT lead leaving a possible coil pack or phonic wheel issue.

Andy Monty said:

Has it had the cam belt done recently?

Click to expand...

I was thinking the same when I read the fault and symptoms too, Andy, especially given the age. Wonder if it's deteriorated enough for the timing signals to no longer be perfectly in sync... but it's worth checking the obvious stuff (plugs and leads) like T has said.

Hi again, thanks for your replies.

I failed to mention before that it currently occurs about once per month and only for that split second. Approx 1000 miles are covered in each month then with no problems so it's VERY intermittent along with the points above!

Is it really worth starting to replace things like the coil pack etc or should I wait for it to get worse or just put it down to being a temperamental thing as it runs perfectly!

As stated the light goes out immediately after releasing the accelerator and doesn't come on again for about another 1000 miles!

Thought I'd give a bit of an update. Above still occurs randomly when on long journeys at high rev's.


The car is on 50k now (from 33k when I originally posted)
Timing Belt was changed at 42k with the garage doing a full service, phonic wheel adjustment (with readouts) and clearing fault codes.



Annoying but still no solution

Have you had the codes read? I think, even though it's only brief, the ECU will still have stored the error.

The paperwork I had back from the garage said the car had these stored,

P0300 Ignition failures recognitions
P0304 Cyl 4 ignitions failure
P0301 Cyl 1 ignitions failure

Strange thing is it certainly doesn't seem to misfire! I've had my fair share of cars with coil pack issues, misfires, faulty Hugo sensors but the punto seems perfect even when it gives a little flash!

On a 300 mile motorway journey it will either do it 1-2 times or not at all.:bang:

No coolant loss, good on fuel and takes a very small amount of oil around every 3-4000 miles so nothing seems out of the ordinary. Just hate having it in the back of my mind when the missis is out on a long journey.

I bought a 2004 Panda 1.2 8v Dynamique a few months ago that has a full main dealer service history. When test driving it, I thought I detected a vague misfire, but could not be sure. As the car was otherwise in top order and with the reassuring service history. I decided to go ahead. Two weeks down the line, I got the engine light flashing for about 30 seconds. I also noticed that my fuel consumption was lower that expected for the car, even though I was carefully manageing my driving style and under acceleration the misfire was certainly more pronounced. Started reading the forum and got myself a fault code reader which returned P0300, P0302 and P0303 codes. I then renewed coil packs and HT leads (all Magnet Marelli)and Plugs (NGK) - even though the plugs looked fine with no signs of lean running or over-fuelling. Even reset the ECU as described on the forum and reset the codes. Perhaps due to the placebo effect, I thought there was some improvement, but the codes returned and the light again came on for short periods, usually when running at light throttle. I got myself some test equipment to double check that ignition systems were good - all A1 - as well as checking compression - again A1. More and more, I started to suspect the fuel system, but just to be sure, changed the oil to fully synthetic Mobil 1 New Life 0W-40 and changed the oil filter which did not look like the dealer has changed it for a long time, even though last dealer service was done only 5K ago. I was surprised how different the car felt/sounded - as if everything was a little smoother and I do believe there was a slight increase in fuel economy (I know, no logical explanation as far as misfiring is concerned!). Biggest difference came, however, when I put a bottle of Cataclean through. Idling sounded smoother and although misfire still occured, there seemed to be less of it. I decided to put another bottle through and fuel economy jumped from an average 41 mpg to 49 mpg (trip computer indicating 53 - 55 mpg) with markedly less misfiring and smoother and more powerful acceleration. On the motorway, I was able to get the trip computer up to 68 mpg with very careful driving! I am now considering sending the injectors for a clean at Injectortune, but am just first putting through some Comma Petrol Magic to see if it would not clear the last few misfirings from occurring which I believe is due to poor spray patterns and the ECU struggling to cope with intermittent variations between cylinders. I also stopped using supermarket fuel and now only fill up with Shell. At the end of the day, the message is probably that a lot of factors combine to improve things, but I would certainly recommend looking at those injectors early on.

Had the car read at the garage again this weekend and this time it's throwing up a misfire on cylinders 2&3.

The mechanic seems to think cleaning up the phonic wheel and a recalibration should hopefully sort it as in his opinion (after what I explained happens) it's a false reading.

Mine did this, I replace coil pack and Ht Leads, fixed it. Very cheap fix too.

P0300 Ignition failures recognitions
P0303 Cyl 3 ignitions failure
P0302 Cyl 2 ignitions failure

Only ever happens when doing about 60mph (96kph)

Ive change spark plugs, coil pack and HT leads and still have the problem :bang:

Any ideas

Just some feedback: No further improvement achieved. I still get the occasional MIL on and will now send those injectors for a clean as soon as I can find the time to be without the car for a few days.

More feedback overdue: Had the injectors cleaned at Injectortune (great service and speedy return). Although the spec before/after cleaning shows only a minor improvement, I am happy to say that the felt misfire is completely gone. For some reason, the MIL still comes on occasionally, even after having cleared the codes, but as the car pulls cleanly and the fuel economy is hovering around an average 48 - 50 mpg, I have decided to ignore it. Fuel economy of as high as 56 mpg (calculated, not going by the onboard computer) is regularly achieved on steady runs. As said before, it is worth having those injectors checked/cleaned.

Check fuel trims. Could be a leak or a bad fuel pump.

Did you ever do the phoenic wheel reset?

DGPunto said:

Did you ever do the phoenic wheel reset?

Click to expand...

Hi, i have linea 1.4 8v, timing belt changed 1000km ago and noticed that at speed 110km/h, rev 3500 at 5th gear, mil blinking..
Not at 4th gear same rev..
When i
But car goes ok, rev goes over 5500rpm etc.. didnt check error code yet,
Didnt notice any other thing...
Shall i go service? Any idea?
For error code and try again at high speed, i can look only at weekend...

Solved by phonic wheel reset
P0300, p0302, p0303

Great