Technical Juddering 2 - 3k rpm

[Sumilidon]

I had a quick search but struggled to find anything that met the situation exactly.

Basically, under heavy acceleration between 2k and 3k rpm, my 2002 1.2 8v Punto is juddering quite badly as though it is missing.

From general searching I am under the impression it is one or more of the following
* Spark plugs
* HT Leads
* Coil
* ECU

As it only judders between these 2 - 3k rpm I would expect the sparks and leads to consistantly judder - but I may be wrong. ECUs are alien to me.

It continues to judder even if the engine is warmed up. No warning lights

Any suggestions as one goes to an auto electrician, the other a mechanic.

 

[red]

Have you had the plugs out yet to see whether they all look the same? The coils each supply two cylinders. The ECU drives the coils and there is a known fault where defective coil overloads the ECU, damaging its output circuitry. Don't despair yet though as a faulty ECU output would almost certainly be apparent as misfire at any rpm.

red

 

[Sumilidon]

I'll be honest with you, I wouldn't know what I'm looking for with sparks.

The car needs a full service so figured while there, get the sparks, leads and coils done as well. Just ticked 60,000 miles so worthwhile.

Outside of 3k rpm the car revs just like it used to so better sooner than later before more damage caused.

Thanks

 

[red]

If you can take the plugs out, have a look at the colour of the tip. It should be a light brown. White/burnt/damaged can indicate overheating or weak mixture. Black can indicate rich mixture (poor combustion, carbon deposits). Oily deposits can indicate worn parts (piston rings for instance). If you look in a Haynes manual (any car), there are some useful pictures of spark plugs at the back.

You'll need a plug spanner or a socket set with a plug socket. If you do have a go, try to avoid dropping any muck down the hole (cleaning loose debris away first is recommended but can be difficult). When refitting plugs be careful not to cross-thread (you should be able to screw in by hand to start with) and don't go too mad when tightening (the head is aluminium).

red.