Hi have a 2001 1.2 sporting and it has a misfire on number 3 cylinder . Now i have changed the coil and plugs leads but its still the same . Done a compression test and they are all healthy and even . When i take off number 3 plug lead i can see and hear it sparking onto the cylinder head so i know thats fine . Now i have checked to see how many wires go to the coil just to confirm that the ecu does or does not fire each one of the 4 coils separately . 3 wire plug into the coil which leads me to believe the ecu has only 2 live wires going to the coil so i am thinking maybe the ecu is firing the injector late . The head gasket was changed before i bought the car which leads me to believe somebody though it was the head gasket . Also the oil light has come on and wont switch off even after i disconnected the wire going to the switch . Can anybody shed some light on this or have had a similar experience to this

put a vacuum guage on the inlet side see if shes steady at 18 on tickover
check by moving spark plug to another hole that its not breaking down under load
can you replace the ht leads for the same reason ie breaking down under load
the oil light nearly got me last year when i thought it was a faulty switch but turned out there was a hairline crack in the pickup pipe
try a new sender first
(have you still got the 130tc? love them always did) even though the fuse boxes were made of cheese

Yes still got the 130tc and have being driving it around for the summer . Shortly it will come off the road for the winter .
I think the puntos ecu is gone . The cyclinder is sparking , it has compression and fuel is being injected into the engine . I have taken the plug out and its wet . So i reckon the fuel injector is injecting either too early or late .

Hi, i know this is a very old post but did you finally sorted this out? I have exackly the same problem on cyl no4.

Thanks in advance
Panagiotis

ok1gr said:

Hi, i know this is a very old post but did you finally sorted this out? I have exackly the same problem on cyl no4.

Thanks in advance
Panagiotis

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Are the cylinder pressures ok..?

ok1gr said:

Hi, i know this is a very old post but did you finally sorted this out? I have exackly the same problem on cyl no4.

Thanks in advance
Panagiotis

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Have you tried new HT leads.? No.4 lead is the one that always fails shortly after splugs have been fitted. Usually due to the mechanic not unplugging HT lead from ign coil before pulling lead off the spark plug. It over stresses the lead.

Hi, thanks for your replies.
Yes i did run a compression test (twice with other equipment), both cold and hot. Every cylinder was on 180-190psi within 5 strokes. Cranksensor off, plugs off, Throttle wide open.
I also run an idle compression test (read it somewhere). Same compression on all cylinders 90-100psi with engine running, i got one plug off each time.
I tried another ht lead, nothing
i swapped the spark plugs between cyl 1 and 4. Misfire didn't move
i swapped the injectors between cylinders 1 and 4 no difference.
The coil is new and i have strong arc on every ht lead.
I also studied how the coil works. Since it only have 3 contacts It seams that each time 2 spark plugs fire simultaneously. The cylinder that needs to fire and onether one. Seams to me same logic like early alfa romeo twin spark motors. Anyway i swapped the ht leads on the coil side between 1 and 4 (those who spark at the same time) still no difference, so coil is definattely ok.
At last i swapped injector wiring between 3 and 4. I know that it wouldn't inject at the correct time but i considered that the vacuum would take the fuel in the cylinder at next cycle and since the rpms are steady there would be no problem.
And AGAIN ONLY cylinder no4 will missfire.


Let me elaborate the missfire a bit more.
When on the road it seams that power is ok or almost ok. (I just purchased this punto so i'm not familliar with it's performance)
When on idle it missfires. I get no obd error messages, lambda works ok, fuels rich on idle (lambda intergrator on 0.9)
When i unplug ht lead no4 it has very little or almost always no difference. Same rpm, same rough idle.
But if i have it for a short run without ht lead no4 it's awfull and much worse.


Sorry for the long post, i'm waiting forward for your suggestions.

Back to basics.... something must have been missed.
Have you checked for an air leak.?
Remove the injector and check for debris in the gauze on the inlet side of injector. Check and compare injector resistance. Inspect the rubber o ring on the injector. Check and compare the ohms readings for all HT leads.
Check cambelt timing, make sure you use the locking pins for both cams. Need to check piston stroke on all cylinders, you could use the timing tool rods.
Did it have this fault when you bought it.? Does the engine sound noisey? Have checked the cooling system for Emmisions.? (Headgasket) cylinder leak test.?

do you get lower or higher compression, if throttle is not opened fully?

Thefox said:

Back to basics.... something must have been missed.
Have you checked for an air leak.?
Remove the injector and check for debris in the gauze on the inlet side of injector. Check and compare injector resistance. Inspect the rubber o ring on the injector. Check and compare the ohms readings for all HT leads.
Check cambelt timing, make sure you use the locking pins for both cams. Need to check piston stroke on all cylinders, you could use the timing tool rods.
Did it have this fault when you bought it.? Does the engine sound noisey? Have checked the cooling system for Emmisions.? (Headgasket) cylinder leak test.?

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I sprayed some carburator cleaner around the inlet manifold but revs did not not increase. Also keep in mind that it's running rich on idle not lean. I did not check injectors' resistances but i will. I remind you that i swap injectors between cylinders and the problems persists at cylinder4. orings are perfect, there was some debris in the inlet side of injector 4 but it wasn't the problem. I will also check resistances for all ht leads but i already swap lead no4 with another one. I don't have the timing tools but i think i can use a mirror to see the camshaft position and pointed rods like depth gauge. Don't you think so? I thought that it could not be incorrect timing since i would have missfires on all four cylinders.. Wouldn't I? It did have this fault when i bought it among with many others. In the beginning i thought it would be much easier. The engine sounds definitely noisy but this happens because there is an air induction kit installed. I think i cannot hear any valves ticking but it's not easy in this situation. After a month of owning i did not notice any coolant missing. I don't have the means to perform a cylinder leak test..


*Forgot to mention that i also measured temperature on the exhaust manifold. After about 5 to 10 minutes of idle running cylinders 1-3 are at about 190-200degrees celsius right after the head and cylinder no 4 is at 150 celsius.

flisko said:

do you get lower or higher compression, if throttle is not opened fully?

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I measured with throttle not fully opened just once, but i think it was almost the same. What are you thinking? Can you please elaborate on that?
Actually the throttle is fly by wire. I'm not sure when i press the accelerator all the way down if the throttle will be fully open.

i was just wondering if there is alot of difference in readings between throttle fully opened vs closed

After you've checked the things I've suggested I think you need to remove the cam carrier to inspect the cam lobes. It could be the cam lobe worn down. Could be an oil way blocked or the cam lobe not manufactured correctly.
Seen this on a sedici diesel before.
If it has been over fuelling on this cylinder for a long time it will have caused a lot of wear to the piston rings too.

Thefox said:

After you've checked the things I've suggested I think you need to remove the cam carrier to inspect the cam lobes. It could be the cam lobe worn down. Could be an oil way blocked or the cam lobe not manufactured correctly.
Seen this on a sedici diesel before.
If it has been over fuelling on this cylinder for a long time it will have caused a lot of wear to the piston rings too.

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Ok, i will. One more question. Do you insist to check cam timing? Could there be any posibllity that the timing is out and have problems just in one cylinder?

I would check all the basics first including cam timing yes

Thefox said:

I would check all the basics first including cam timing yes

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ok so i had the same issues with my girlfriends dads car. 1.2 16v sport. we went through the whole process of a new ecu, fuse box and key barrel which i fitted, no problems there but the fault was still in the car. he said he had new coil pack, spark plugs and ht leads fitted. so i said ill have it again for a few more hours.... changed around the sparks, cleaned them, changed the injector in 1 for 2 and still nothing. so i completely took off the lead on cylinder 2 from both ends and completely swapped it for cylinder 1. yes the lengths are a tad off now ones too short and ones too long but hay! worth a shot! so i got rid of the code and it WORK!!!!! no more issues with the car it fired up and ran with a load of power. people can you try it as well to see if it solves your issues.

good luck!