Technical Fiat punto not accelerating

[SimonUK12]

I’ve just bought a 61 plate fiat punto evo which runs fantastic most of the time. However, there is no acceleration after coming to a stop at a roundabout or sliproad. Always after motorway driving. This is sporadic and doesn’t happen all the time. Engine still ticks over but nothing from the foot pedal. I have also noticed the occasional idle revving.

Once I restart the car and revv it, everything is fine and the car runs perfectly.

- new fuel filter fitted
- switched away from supermarket diesel
- DPF deep cleaned
- no engine warning lights

Today I did get a ‘check glow plugs’ indicator.

Have had previous indicators of “hill start unavailable” and “esc unavailable” twice now too. But they go off once the car is restarted.

The team at the garage affiliated with the dealer are trying to help as much as possible but with no dash lights or error code it’s proving difficult.

I’ve only had the car less than three months.

This has all happened over about 3000 miles, whilst I have been trying to drive it as much as possible after each potential fix.

Any advice would be great.

 

[Mike1alike]

Is it a diesel engine?
Considering this

I have also noticed the occasional idle revving.

I'd say you either have a vacuum leak or the idle air control valve is faulty. Also, the MAP sensor could be defective and doesn't do an accurate reading. Like when you press the accelerator the admission pressure modifies and more fuel should be injected. If MAP sensor doesn't do that corect reading, no command for more fuel is given.
Do you have turbo on the engine?

 

[SimonUK12]

Is it a diesel engine?
Considering this

I'd say you either have a vacuum leak or the idle air control valve is faulty. Also, the MAP sensor could be defective and doesn't do an accurate reading. Like when you press the accelerator the admission pressure modifies and more fuel should be injected. If MAP sensor doesn't do that corect reading, no command for more fuel is given.
Do you have turbo on the engine?

Thanks Mike,

Yes it is a Diesel engine and I understand it has turbo. Will ask the garage to check out the MAP and air control valve. My worry was a vacuum leak but I was hoping not the case with losing power only after coming to a stop at junction/ roundabout/ sliproad. Drives beautifully on the motorway which is exactly what I need it for- for work.

 

[SimonUK12]

Put a new air filter on and fuel injector additive cleaner. Have thrashed it with work motorway driving this month with work (3000 miles in 4 weeks). Ran perfectly until today. Then lost power again and idle revving recommenced. Considering fuel injector additive again as appeared to do the trick last time

 

[Mike1alike]

Does the car revs by itself on idle? Like to 2000 RPM or so, repeatedly? If so, I've had this problem last summer on my Punto (petrol engine) and it turned out to be the IACV (idle air control valve or stepper motor) and the fix was a new IACV.