Technical Fiat Punto Mk2 Petrol 1.2 16V not starting

[crankshaft]

I've only ever had one coil pack go bad, it was on an '02 Punto 1.2 8v and that only started acting up when the engine had got properly hot. Symptoms were as you're describing. I know the one you have is only six years old and that it would be bad luck......

I can try to get a second hand coil pack to test. I would be surprised after testing that all spark plugs have spark, that it is the coil pack, but temperatures probably play a role too.
I forgot to mention but the car is burning a lot more fuel, like 2 to 3 times more.

 

[varesecrazy]

Good it now runs....

But it's a weird thing you made a change with a sprayed fuel..

Sounds FUELLING related, rather than a major mechanical fault

Yes it will be an exhaust sensor putting on that Yellow light.. That is what it's function is

On a perfect young motor, it takes a few seconds to extinguish as the motor starts to run efficiently

 

[crankshaft]

I scanned the for fault codes with Multiecuscan

So the misfire is on cylinder 4... ok that's something new... I was expecting cylinder #1.

 

[AndyRKett]

Go back to the start. 1 what condition are the spark plugs in, HT leads; potentially consider replacing the coil packs ( they’re pretty cheap)

Do you have good fuel, you’ve not accidentally put diesel in the tank ?

Servicing, when was the oil last changed, air filter,

Timing, has the cambelt slipped a tooth, I just bought a timing tools set for my car with the same engine got about £20 off eBay,

The flashing light means the ECU is detecting a misfire, often this relates to the coils, but given the difficulty in getting it started I suspect there is a timing issue.

Forget about the carbon deposits nonsense, firstly it’s not a thing and secondly after driving 100 miles you’d expect it to have sorted itself out by now

 

[crankshaft]

Go back to the start. 1 what condition are the spark plugs in, HT leads; potentially consider replacing the coil packs ( they’re pretty cheap)

I just changed the spark plugs, that's how this ordeal begun. The spark plugs I always use are NGK DCPR8E-N.
I conducted some tests, recommend in this thread, to see if the HT leads were OK. Putting one of the old spark plugs against the engine's metal, I could see a spark jumping 5 millimeters in the spark plug for all 4 HT leads. Also tested the resistance of the HT leads many many times, across different days. Always got the same values: 3.7 KΩ, 3 KΩ, 2.2 KΩ, 2 KΩ. I also tried shaking them, while measuring, to see if the Ohms value would change (simulating a problem/degradation in the wire).
About the coil packs, is there no sure way to test them? I would assume that because I could see a spark on all 4 HT Leads the coil pack was OK, but I can see that this test would not account for the frequency that the coil needs to strike sparks, and a fault is possible. I looked up new coil pack prices for my engine online, and at the rate my car is burning fuel, and given the current fuel prices, I already burned through half the price of a coil pack yesterday It is definitely worth checking.

Do you have good fuel, you’ve not accidentally put diesel in the tank ?

No diesel in the tank. I never tried it, but I think the diesel nozzles, at the gas station, are different and won't fit in my car.
Yesterday, I had to put 12 liters of petrol (unleaded 95 petrol), because the car was burning fuel too fast. I had to do it at 2 different gas stations, 6 litters each time. The car went pretty low on fuel, because I wasn't planning for it to burn fuel so fast, so I assuming is not a fuel quality problem.

Servicing, when was the oil last changed, air filter,

Oil, oil filter, air filter were changed 6 months ago, the air filter looks new still.

Timing, has the cambelt slipped a tooth, I just bought a timing tools set for my car with the same engine got about £20 off eBay,

The flashing light means the ECU is detecting a misfire, often this relates to the coils, but given the difficulty in getting it started I suspect there is a timing issue.

I can try to look into a timing tool set. Is not a job I ever did before, and it is a bit intimidating to me.
The timing belt, the tensioner, and water pump were changed some 4 months ago. Unless the service was, maybe, incorrectly done. But when I picked up the car I didn't had any engine symptoms. The timing belt kit was from SKF.

Forget about the carbon deposits nonsense, firstly it’s not a thing and secondly after driving 100 miles you’d expect it to have sorted itself out by now

I see your point.
But you don't think the reason the car didn't start before was because of the deposits that got lose? And in the mean time they burned off? Why would the car start easy now and wouldn't start at all before?

 

[crankshaft]

Started the car this morning. It starts just fine in a cold morning.

Going back to the rough idle which started all this, did you hear any different noises? A stuck inlet valve can sound like a chuffing noise from the air filter and a burned exhaust valve more of a spitting noise from the exhaust. You may not have a compression tester, but if you get some sort of stick/rod with a bit of rubbery stuff that will cover the plug hole you will fairly easily tell if one cylinder is different from the rest. Won't solve your starting problem, but...

I can hear a sound from the exhaust pipe, is hard to describe it, but that noise is also audible at a different tone in the engine itself.
I read online that there is a test you can do in the tail pipe, with a paper, to see if the exhaust pipe is also sucking in air.

I did the test on the exhaust pipe, by holding a cloth I could see the cloth was being sucked in by the tailpipe.
This was hard to see to "the naked eye", I had to use the slow motion camera on my phone, and in the slow motion video is quite evident that air is being sucked in through the exhaust pipe.

I am sharing the videos that I took here:

Video in normal speed



Video in slow speed




This means there is a problem with the valves right? Given the miss fire on cylinder #4, I am guessing that's where the problem is no?

 

[boguing]

It's certainly an indication that something's not right but there's lot else going on in an exhaust system than just waste gas coming out. I'd rule out the easy things first.

Having said that, you didn't respond to my suggestion of a diy compression tester. A stick or rod a bit bigger than the plug hole with a bit of something rubbery stuck on the end will definitely tell you if you're not get equal compression on each cylinder.

 

[jackwhoo]

I can try to get a second hand coil pack to test. I would be surprised after testing that all spark plugs have spark, that it is the coil pack, but temperatures probably play a role too.
I forgot to mention but the car is burning a lot more fuel, like 2 to 3 times more.

Yes try a different coil pack

Yes it will use loads more fuel if it is misfiring

If it misfires/shakes more under load (high gear accelerator pressed down) that is indicative of a weak spark .

Edit-

Your mes screen shot shows no signal from pre cat lambda sensor.......
That could be significant . Does the error come back if erased?

 

[crankshaft]

Edit-

Your mes screen shot shows no signal from pre cat lambda sensor.......
That could be significant . Does the error come back if erased?

I ereased it, and it didn't come back.
It was the first time I saw that error, and the car had no faults when I was having that "non starting issue".

 

[George1982]

I have not checked for intake air leakes, besides visually inspecting it.
But I feel the car vibrating a lot when driving at higher speed, with the engine at high RPMs, I thought that would point to something else other that a vacuum leak?

A small leak should disappear in load,not a huge one