Technical Punto 1.2 8V not firing on Cylinders 1 & 2.

[armysurplusspecial]

Hi all, newbie to the forum so thanks for having me...

My childminder has a 2003 Punto 1.2 8V, nice little car, had it a couple of years.

She called me Friday to say the car had starting juddering and making a "knocking noise"

First impressions- engine misfiring, no change in tone when i pull the plug lead on cylinders 1 or 2- both not firing. if i pull 3 or 4 it cuts out.

The knocking noise sounds like severe detonation/ pinking when you try and blip the throttle.

i went over yesterday, changed the plugs (not been changed in years- No1 was so rusty i had to hammer on a 13mm 12pt socket to get it out..) and changed the plug leads (yes they are in the correct order). We have a spark at all 4 plugs but still 1 & 2 cylinders not firing. This would rule out coil packs in my opinion as they are paired with 1 & 4 and 2 & 3.

I am going back over today to do a compression check on the car, to rule out head gasket between cylinders 1 & 2. i will also check the cam, make sure that's not wiped out.

Anyone any other ideas? Could the ECU be playing up? I need a new one anyways as the ignition key is so thin it's close to snapping, so was going to fit a complete lock set and ECU.

Any advice would be appreciated.

 

[Ziggy122]

A - check the resistance of all the injectors across there 2 pins
B - Check for a 12v feed to each injector - They all share the 12v feed with the coils as well, looking for a break starving 1 and 2
C - If you can test the pulses of the injectors to ensure there actually firing

But its odd that that 1 and 2 aint firing

Also
What were your compression results?
Have you swapped the coils around so 2 and 3 are swapped over / 1 and 4, to ensure its not the rare failure of just 1 side of the coils' - it does happen, but rare

Ziggy

 

[armysurplusspecial]

Hi Ziggy, thanks for the reply.

A. What should the resistance be?

B. Will do.

C. I assume with a test light? or the old fashioned screwdriver to ear??

i have not done the compression test yet... i'm heading over in an hour to do that.

i swapped the coils over as you said, although 1 & 2 use the same side of the 2 different coils... so if 1 side was gone on both..! i did try a new coil pack however, it made no difference. i can hear the spark as i pull the plugs, i have also pulled each lead and put a plug in to see if it's sparking, it is.

There is fuel in the rail... i removed the plug and pushed in the shrader type valve, fuel rushed out under pressure.

 

[Ziggy122]

Auto-data states 14.5Ohms

You can check to see if the injectors are firing with screwdriver test

i'd also tbh pull the injectors / injector rail out and see them all firing into plastic bottles - to check they A - firing and B - good spray pattern

I have to stress though - punto injectors DONT normally fail....
But it could happen

btw compression i'd like to see 160psi -200psi dry
And with little change on wet test

Ziggy

 

[armysurplusspecial]

Looks like a head gasket/ mechanical issue....

Cyl 1 = 25 psi
Cyl 2 = 25 psi
Cyl 3 = 170 psi
Cyl 4 = 175 psi

Are the heads on the 8v clearance heads, ie unlikely to have bent valves if there was a belt slip or something similar?

 

[Ziggy122]

Looks like a head gasket/ mechanical issue....

Cyl 1 = 25 psi
Cyl 2 = 25 psi
Cyl 3 = 170 psi
Cyl 4 = 175 psi

Are the heads on the 8v clearance heads, ie unlikely to have bent valves if there was a belt slip or something similar?

Wow, thats low...
Thats a clear blow between cylinders so yes its a HG time

I bet your will find a nice burn through in there

the 8v engines are FIRE engines, which means they dont bend valves on cambelt snapping
Or they shouldn't

The only thing is they are fussy about the phlonic-wheel for the crank sensor
it has a tiny pip in it, for fitting, if its not the correct way - the engine never runs

But it sounds like you've got a days work ahead of you

Ziggy

 

[armysurplusspecial]

Yes i will have a busy couple of days! i will take the head off this week and get it skimmed, i will hopefully replace it at the weekend on my weekend off...

i will put a new coolant pump, thermostat on as well to be safe... as well as the normal belt and tensioner etc etc.

Thank you for your help and advice Ziggy, much appreciated.

 

[Ziggy122]

Yes i will have a busy couple of days! i will take the head off this week and get it skimmed, i will hopefully replace it at the weekend on my weekend off...

i will put a new coolant pump, thermostat on as well to be safe... as well as the normal belt and tensioner etc etc.

Thank you for your help and advice Ziggy, much appreciated.

FYI - Avoid cheap thermostats, they have been causing issues amongst members here including me

People have settled with either a genuine fiat unit - or gates
I had the original back in after a couple of QH's and one from halfrauds

Somereason punto's are fussy and i dont understand its physically possible

ziggy

 

[varesecrazy]

Hi,
head gasket can be changed for @£10;


bolts can be torqued twice.. (re-useable)

gasket is @a tenner delivered,
no other seals require replacement..

BUT the thermostat IS well worth changing,

LOTS of info / how to's on here.., as HG's are a common reason for posting..!!

for reference I disconnect fuel lines and Exhaust lower pipe,
and leave BOTH manifolds in situ,
Charlie

 

[armysurplusspecial]

A quick question for you all, do i need to strip the head for a skim? cam/ valves etc??

 

[varesecrazy]

yes - but if checked for flat there's little need,
I've never needed to..,
Charlie

 

[Ziggy122]

ask you local machine shop if they require the cams out or not

Just bear in mind, the bucket and shims need to be kept in the same order as they come out
Otherwise its a full reshim job afterwards

Ziggy

 

[flisko]

ask you local machine shop if they require the cams out or not

Just bear in mind, the bucket and shims need to be kept in the same order as they come out
Otherwise its a full reshim job afterwards

Ziggy

what is that

 

[Ziggy122]

what is that

Whats what?
Bucket and shims?
Tally ho?
Peanut butter jelly?

Ziggy