Punto 1.2l 8v SOHC vibrating on idle

[Chrisdmrf]

Mk 2 Punto 1.2l 8v SOHC vibrating on idle

Apologies if this has been posted before. Last night I think I clipped a pot hole (it sounded that way), since then the car has a rough idle, runs poorly and is making a metallic rattle under load.
I have:

1. Checked timing
2. Checked leads
3. Visually checked lifters

While I was under the car I also noticed it is blowing from the exhaust at the 1st connection (between CAT / Downpipe and 1st section) and also from 2 month old back box (seam).

I obviously need to sort the exhaust leaks but would this be the cause of the issue or am I looking at HG failure?>

Any suggestions would be appreciated, thanks in advance

 

[fingers99]

Re: Mk 2 Punto 1.2l 8v SOHC vibrating on idle

My guesws is it's related to the pothole.So, check out and fix the exhaust first.

It's very rare that a blown HG gives rise to noise, only sure way to tell is a compression test.

Not sure what "visually checking lifters" implies -- they're not hydraulic on the 8v engines, you need to check the clearances with a feeler guage.

 

[Chrisdmrf]

Re: Mk 2 Punto 1.2l 8v SOHC vibrating on idle

thanks for replying, going to change plugs and leads too

 

[Chrisdmrf]

***UPDATE***

Changed plugs and leads - slight improvement but still "Chugging" on idle and rattles when revved. Coils seem ok, no discernible difference when unplugging coil packs.
yesterday I visually checked the timing, if it were out by one or two teeth would that make a major difference?
Failing that am I looking at valve failure? HG failure?

I really need to get this going as I use it to get to work.

 

[fingers99]

One or two teeth will make a lot of difference.

Valve failure extremely unlikely.

You may have a coil pack on the way out.

Code read?

 

[Bushboy]

Could be a number of things (exhaust wont help...)... but you say disconnecting the coils made no difference?

If you disconnected one and it made no difference then it is ****ed. You would notice a massive difference if both were working and you disconnected one as it will effectively kill 2 cylinders, giving symptoms you describe.

 

[Chrisdmrf]

One or two teeth will make a lot of difference.

Valve failure extremely unlikely.

You may have a coil pack on the way out.

Code read?

Could be a number of things (exhaust wont help...)... but you say disconnecting the coils made no difference?

If you disconnected one and it made no difference then it is ****ed. You would notice a massive difference if both were working and you disconnected one as it will effectively kill 2 cylinders, giving symptoms you describe.

I retried coils and found one was definitely shot, engine died straight away, replaced both coils and there is progress. Engine much better at idle, much smoother.
Took for a test run, not good. Still sounds like it's missing one cylinder, and a rattle when under load, also very smoky but has been sat for a week.
Going to re check the timing in case any other ideas before I rip the head out?

http://youtu.be/KDME_5c9f68

Rechecked timing - OK
New Coils
New Leads
New Plugs

Thoughts:

Blocked injector?
Stuck / worn / Bent Valve?
Hole in Exhaust (Pinhole as above)?

 

[Chrisdmrf]

OK, problem found. Process of elimination got me to the point of suspect HG failure.
Head off and sure enough HG burnt out between 3 & 4. Thanks to those that helped