my punto has recently developed a problem, when running the car will not idle for longer than 20 seconds with out stalling and then when running it often has a lack of power - similar to a misfire.

i have checked ignition system and various sensors and found they are working correctly, but i did notice when the engine begins to stall the injector is missing a beat so to say, is this normal? or is there a problem with the injector? or a intermittant fault with a sensor somewhere?

any help welcomed

thanks

Injector missing a beat? How do you know that?

My first guess would be TDC sensor. I'd very much doubt if the injector (injectors?) are at fault.

But first do the old run the engine in the dark, bonnet up, look for blue flashes trick.

Any sign of the management warning light?

Cheers

SPD

well with the engine idleing and the air box of, you can hear the injector clicking and see fuel being sprayed into the inlet, its is doing this at a constant rate but every few seconds its stops injecting for a few "clicks". its a SPI.

i will check for sparking in a hour or so when it gets dark.

and the TDC sensor, when i turn the engine over i get a voltage, if this was at fault am i rite in saying there would be no spark? this doesnt seem to be the problem

no warning lights at all, only the injector for a few seconds after starting but that is normal....... i hope

Often the signal becomes intermittent. At that point you'll loose spark and fuel. Problem is often the wiring, which is in the line of fire of everything, but just about impossible to fix (sheilded cable, etc.).

Possibly just injectors blocked? Just an idea

is the crankshaft sensor the only sensor that could affect the injector? so if this is the problem it will be that sensor, or the wiring to and from it, the injector and the ecu

Lots of sensors will affect the injector, but the TDC sensor has the effect that, when the ECU recieves no signal, it cuts fuel and spark. Imagine an intermittent loss of signal and you have a misfire, while a permanent loss of signal gives you a dead engine.

Can't see a blocked injector suddenly unblocking itself.

The only thing that confuses me slightly is the lack of management light.

This would tend to confirm TDC sensor as the ECU is shutting down so doesn't see anything 'wrong'

If it was a missfire caused by lack of spark the o2 sensor would see unburnt fuel and flash the management light.

Cheers

SPD

hi, just to let you all know i have fixed my punto.
replaced the injector and it solved the problem, thanks for all your help