Basically partners Fiat Pinto Mk2 2002 has a slight problem. It seems to pulse slightly on idle and struggles on hill starts with slight hesitation. Now we know it’s not the coils as these were replaced two weeks after we bought the car. Engine management light is not illuminated either. Any ideas? Could it be fuel filter related?

A Pinto?
Lactose intolerance.

Is it a bit depressed?

What colour is it?

Stupid autospell on mobile. Fiat Punto.

If I remember correctly they are VERY sensitive to the correct spark plugs. Wrong ones and it can wreck the coil or at least not run right.

Failing that it could be something like the MAF or MAP depending on which it has.

Could be lots of things. Why do you suspect fuel filter?

pulse slightly on idle

Likes its vibrating, or is it temporarily cutting out, or is it constantly increasing and decreasing the engine speed when at idle?

Same when warm and cold? In the dry and damp? When up to speed it’s fine?

struggles on hill starts with slight hesitation

Can you elaborate a bit please.

I’d guess 10p of someone elses money that its either a sensor: lambda / air flow, or coils.

1.2 , 8 valve ?

If so , throttle potentiometer used to be a common fault . Can be bought as a spare part with out replacing the complete throttle body . Can be checked in live data using diagnostic equipment .

There are special tools to replace it , but can be done without using them if you’re carfull .

It’s a 1.2 16 valve Elx Automatic. Basically when it idled it sort of struggles ever so slightly but is fine under load. Hot or cold engine not really a factor. Just does it at idle and with car facing up or down hill. Revs don’t increase or decrease its like something is stopping fuel getting through. Or like if your in too high a gear going uphill in a manual car that type of kidder but not as bad.

Now we know it’s not the coils as these were replaced two weeks after we bought the car.

New does not = definitely working

Learnt from bitter experience…more than once (slow learner).

Not saying that might be the issue mind.

sounds similar to the problem we had (different car though), replacing the temperature sender unit sorted it.

At full tilt – it’s ok? On the motorway / accelerating hard? If it is ok I doubt it’s fuel related (you havent put diesel in there?).

I’m guessing you couldnt borrow an ODB2 reader from someone you know? Some pending failures dont always light up the engine management light but do register.

BTW – I hadnt in anyway imagined it would be an auto – is it exactly the same in neutral as “D” when idling?

BTW 2 – I thought I had a daft user name!

It’s not as bad in neutral and it’s a bit sluggish under hard acceleration.

When and how many miles ago was it last serviced

Did you change the plugs

Were the leads changed with the coil.

If the answer to any of those is no thats where i would start.

HT leads as above are a good cheap fault finder, and also should be part of a service regime so you’re not losing anything by replacing them.

Check/replace sparks. Again if you haven’t changed them in a year or 2 then just replace them and call it a service.

Check the crank sensor is fitted securely. (lhs of engine bay as you look under the bonnet, down below the plastic timing belt cover down the bottom of the engine, goes onto the crankshaft pulley, wire comes out towards the radiator).

Vacuum hoses (plastic cover near the lhs wiper arm pivot – nearside of car) can split or fall off connections.

I’ll have a think and see if i can remember anything else obvious on mine.

Another thing to check for is burst or perished vacuum pipes, these can lead to a discrepancy in manifold pressure and the engine ca surge as more fuel is delivered, then dies back, then surges, then dies back etc…etc..