Technical Flashing amber engine management light and p0300

[eddie95]

Hi all,

I have a 2005 Punto 1.2 8v facelift model.

When I bought this car, whenever it was cranked, after the engine would turn over, it would make a cough sound. I assumed this was the starter teeth not catching onto the starter ring on the flywheel properly.

Anyway, there I was on the motorway, when after about 70 mph, the check engine light flashes, and as soon as I slow down, it disappears. I plugged in my OBD device into the car and found the code p0300. There was no other code telling me what specific cylinder had misfired, just that there was random misfire. When the light was flashing, I couldn't notice misfire as the car was running perfectly fine, so I didn't think much of it.

About a week later, I went on the motorway again and the same thing occurred with the flashing light, but as I pulled into my drive and tried cranking the car again, it made a horrible noise as though the flywheel starter ring and starter teeth were grinding against each other and wouldn't start. So I replaced both the starter motor and the flywheel completely.

It was now cranking fine with no cough sound as mentioned before. As I went on the motorway again, I tried keeping my speed low enough to stop the engine light from flashing, but on a slope, I went faster than anticipated. Next morning, when I tried starting the car, there was a very minor cough noise when the engine turned over. Fast forward a couple of days and the starter motor has completely died.

Could it be possible that this misfire issue is affecting the flywheel which effects the starter as the crankshaft is connected to the flywheel. And I am assuming when misfiring, that the crankshaft experiences power strokes from the pistons which it was not designed to do.

A quick note if it will help:

There was a small oil leak at the valve rocker cover, so I had that replaced. Could it be the valves or not enough pressure causing the problem?

Any help is greatly appreciated.

Thanks

Eddie.

 

[Ziggy122]

Sounds like you wasted your time to me personally with a flywheel and starter change

Why?
Punto's are nutorious for misfiring

Usually because
The HT leads are always past it
The spark plugs have never been changed
Coil packs are prone to causing a misfire
Lack of ignition maintenance causes the ECU to burn out

My advise for the random misfire
Start by replacing the HT leads and spark plugs and monitor the situation

p0300 is Random misfire detected, ie its not always the same cylinder, its say 3 cylinders but there not doing it consistently, only missing once every so often

Ziggy

 

[eddie95]

Thanks for the reply. The thing is, my car didn't want to start whatsoever, and my mechanic told me the flywheel had worn teeth.

So does the misfire have no effect on the flywheel?

And I will be changing the leads and spark plugs.

 

[eddie95]

Also, why would it misfire at around 70mph and never under that speed?

 

[Ziggy122]

Also, why would it misfire at around 70mph and never under that speed?

Replicate the engine speed at over 70mph in a different gear

for example, if your doing 3.5k @ 70mph in 5th

replicate 3.5k in 2, 3 , 4th and see if the misfire occours then

------

The flywheel is a energy store so to speak
It not only stores engine, but helps the engine turn over at a more consistant speed between power strokes

The teeth on the flywheel and starter motor aren't touching when the engine is running

So either your starter was draggin the whole time - which aint ideal really
or there are other issues

Very rarely hear a car having to have a new single mass flywheel because the starters chewed it tbh....

-----

Something pondering in the back of my mind, it MAY be engine load based causing the misfire, which is usually a coil based problem - deterioating with age

So keep that in mind
You may need new coils too

ITs all a total DIY task as well, coils are 3 plugs, and 4 allen key bolts
5mins each to change

Ht's with airbox off is a case of remove 1 at a time, and refit matching new

Spark plugs, a little more time consuming as cylinder 2 and 3 can be a little tricky - you will most certainly need a long extension bar for your socket if you tackle this yourself

Ziggy

 

[eddie95]

Thanks for the reply and advice. I really appreciate it. I will give them things a try that you mentioned and respond with my results.

Regards

Eddie.

 

[oscar52]

I have the flashing engine management light on mine.


Cant recall where I saw the info - could even have been here! - but it apparently does flash at about 70 due to the Lambda sensor picking up unburnt fuel - does the same if you accelerate hard in lower gears. Its a "normal" thing in those circumstances.


Whether that is correct or not, I don't know. (Probably is if I saw it on here)

 

[eddie95]

Hi all.

Just took the car out and went upto 4000 rpm in 2nd and 3rd gear. No engine light flashed. I then took it upto 70 in 5th which is about 3200 rpm and boom, there it was. I would have thought engine speed and the speed which the car is moving would be linked, but looks like the light comes up at certain road speeds and not engine speeds.


Any thoughts?

 

[oscar52]

3200rpm / 75mph (ish) is pretty much bang on where mine starts flashing.


Have noticed it lower speed but higher rpm (about 5500) with foot hard down

 

[Ziggy122]

Its starting to me like its an engine load based misfire

And if the code read returns the same codes, i would possibly just doing an overhaul of the ignition system.....

As for the light flashing = Misfire detected
It knows because the crank is not revolving at the correct speed that its predicting

Not because its detecting unburnt fuel..... the lambda do that by monitoring the oxygen remaining

Ziggy

 

[oscar52]

As for the light flashing = Misfire detected
It knows because the crank is not revolving at the correct speed that its predicting

Not because its detecting unburnt fuel..... the lambda do that by monitoring the oxygen remaining

Ziggy

As I said, I wasn't sure - I do know my fiat does it all the time at just over 70mph - cant find my original source though

 

[eddie95]

Hi guys.

I pulled out a spark plug and it was covered in oil. Can this be the cause?

 

[eddie95]

For clarification, the oil is in top of the plug from leaking valve cover, not actually in the spark plug.

 

[eddie95]

Hi

I have replaced the ht leads, sparks and coils. Once i started the car up, i noticed that my orange engine light was permanently on and that the engine was rough idling and increasing rpm by itself. I checked the codes and it turns out I have a p0204. I checked and it is either a faulty injector or faulty wiring. Any ideas?

 

[varesecrazy]

Hi

I have replaced the ht leads, sparks and coils. Once i started the car up, i noticed that my orange engine light was permanently on and that the engine was rough idling and increasing rpm by itself. I checked the codes and it turns out I have a p0204. I checked and it is either a faulty injector or faulty wiring. Any ideas?

SURE you've not got the plug (HT) leads in the wrong order..??

OIL around the electrics could be the reason for original misfire under load though..,
Charlie

 

[eddie95]

Hi, I followed the order I used when the initial wires were in place. But I don't see how an incorrect firing order could cause an issue with the injector though :/. What is the firing order, and could you also please state where the first cylinder is (i.e next to cambelt/alternator or next to the battery). Thanks

 

[eddie95]

 

[Ziggy122]

Hi, I followed the order I used when the initial wires were in place. But I don't see how an incorrect firing order could cause an issue with the injector though :/. What is the firing order, and could you also please state where the first cylinder is (i.e next to cambelt/alternator or next to the battery). Thanks

On the Fiat Punto Cylinder 1 is the cambelt end - cylinder 4 in the gearbox end

On the coils - as long as its wired up 2314 or 3241 you'll be fine

Each coils controls 2 cylinders
1 does 2and3
2 does 1 and 4

Since its a wasted spark sytem, if you mixed 1 up so it goes 3 then 2, it wont hurt as both sparks fire at the same time
1 Will fire on compress/power stroke
and the other will fire on exhaust/intake stroke

Since no fuel OR air in cylinder on exhaust stroke - it dont cause a bang = And been on exhaust stroke, its wasted

Ziggy

 

[eddie95]

Thanks Ziggy.

PS (noob question)

Which coil is which. i.e is the first coil pack closer to the radiator or to the front window

 

[Ziggy122]

Thanks Ziggy.

PS (noob question)

Which coil is which. i.e is the first coil pack closer to the radiator or to the front window

If i remember correctly - 1 closest to the radiator is 23 and one closest to the bulk head is 14

if you look carefully into the actual coil pack holder - you should see the firing order cast into the actual holder

Ziggy