Technical Fiat 500 1.3 Multijet Diesel 95 BHP -Slow idle & non responsive accelerator when cold

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Technical Fiat 500 1.3 Multijet Diesel 95 BHP -Slow idle & non responsive accelerator when cold

EmmaDu

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Fiat 500 1.3 Multijet Diesel 95 BHP -Slow idle & non responsive accelerator when cold

Hi All,

Now the weather is getting cooler, my diesel 500 is letting me know about it!

When 11°C or below, upon starting up my car it will only idle at 700 rpm (instead of just over 1000) and has a non responsive accelerator for at least 30 seconds meaning I cannot drive it! It suddenly comes to life after this period and is able to be driven.

Any ideas?

Obviously an issue with something temperature dependant. The glow plugs and their connections have been checked (and all reading well), start up of the engine is clean and no usual exhaust emissions.

It's done almost 30,000 miles and is driven for a 32 mile commute each day, plus more miles at the weekend. Has recently had long drives of over 100 continuous miles and drives well once over this 'hissy fit'.

TIA
 
Re: Fiat 500 1.3 Multijet Diesel 95 BHP -Slow idle & non responsive accelerator when

This obviously isn't right and it's hard to diagnose without some tests.

But it sounds like a fueling issue and perhaps the engine is having difficulty maintaining high enough rail pressure to run smoothly when cold started.

It's like a vicious circle, with the rpm too low so the rail pressure (fuel to the injectors) is low and because the rail pressure is low there's not enough fuel to raise the rpm.

Then it sort of stutters and splutter faster and faster until it's build up a head of rpm/rail pressure and it runs ok.

Reasons for this tend to be crank speed at start up being too low or the injectors are leaking off too much fuel (returning excess fuel to the tank/pump that should be injected) or a bit of both.

Low crank speed at start up is usually battery related, when it starts to get like this quite often you can hang on to the key a second longer as it starts, this just boosts the crank speed a little and can over come the problem until you get the battery and charging system checked or use battery booster pack to see if it fires cleaning with a better crank speed.

The injectors leaking off problem needs a "leak off" test performing on the injectors.
It's quite a simple test to measure what each injector spills off when the engine is running.
They should be all very similar, within around 10% of each other.
A duff injector is usually easily spotted as it pee's out fuel a lot faster than the rest.
I local diesel specialist should be able to help with this, not all back street garages understand modern diesels and they'll be best placed to sort out refurbished or replacement injectors if needed, but first start with making sure the engine is cranking fast enough via a good or boosted battery.
 
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Re: Fiat 500 1.3 Multijet Diesel 95 BHP -Slow idle & non responsive accelerator when

Is it lumpy when it's having a hissy fit?

If so, then I'd guess that one of the injectors is not cooperating until it warms up. The ECU may be able to start the beast on three cylinders and keep it running but if one of the injectors is out, the engine will have a bit more vibration than normal.

Fuel rail pressure could be a goer but less likely at your mileage since fuel pumps and regulators are good for moon-shot mileage usually.

Are you sure the glow-plugs are good? They usually give an error when they fail but if possible (you need a special tool) remove them and make sure they glow when plugged in directly to a 12v battery.


Ralf S.
 
Re: Fiat 500 1.3 Multijet Diesel 95 BHP -Slow idle & non responsive accelerator when

Just another quick check. Is the oil level OK? When was it last changed? Low oil level or old oil that's become thick and gloopy leads to reduced lubrication which can have an adverse effect on engine speed until it warms up. Just a random thought :)
 
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