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View Poll Results: Which of the following applies to you?
I have a 2014 delivered 1.2 500/Panda and I'm experiencing this issue 22 46.81%
I have a 2014 delivered 1.2 500/Panda and I'm NOT experiencing this issue 6 12.77%
I have a 2013 or earlier delivered 1.2 500/Panda and I'm experiencing this issue 11 23.40%
I have a 2013 or earlier delivered 1.2 500/Panda and I'm NOT experiencing this issue 8 17.02%
Voters: 47. You may not vote on this poll

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Old 09-07-2014   #31
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Re: 2014 Fiat 500 1.2 acceleration issues

Quote Originally Posted by jrkitching View Post
Photos of any problem cars with missing bolts would be helpful.
Really helpful...I'd forgot all about the missing bolt theory that I'd read somewhere...i expect that it'll be (or not as the case maybe!) under the heat protection cover at the front?

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Last edited by deef1; 09-07-2014 at 12:17.
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Old 09-07-2014   #32
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Re: 2014 Fiat 500 1.2 acceleration issues

I should mention that another colleague at work also has a 14 plate Panda 1.2, no issues with that either. It's his mums but he drives it occasionally and would very happily tell me if anything was wrong with it
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Old 11-07-2014   #33
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Re: 2014 Fiat 500 1.2 acceleration issues

I've just been reading up on some of these thread about the acceleration issues.

The Mrs 1.2 Panda Lounge (built Feb 14) has this flat spot issue.
The 63 plate 500S loaner (built ??) I have at the moment doesn't.

What I have noticed if you sit with the Panda idling, releasing or drepressing the clutch increases the RPM.

With the 500S, the clutch action has no effect on idle speed.

I know modern cars will often adjust idle when it detects a raising clutch to prevent a stall, my 2.0D Jag did this, but it seems Fiat efforts to do this seem to have caused an issue.

This is just a guess, (as I do drive her 1.2 and seem to drive around the problem) the flat spot - sudden take off appears to be a problem if you input a little too much throttle when raising the clutch.
Raising the clutch without throttle input to get the car rolling, then accelerating doesn't appear produce the same effects.

As I understand it, the throttle bypass would be controlling idle and is being signalled via the clutch switch to open up more when the pedal is raised, so opening the throttle body to allow more air in while the bypass is wide open controlling engine speed may be bogging the engine down due to more air entering that it's fueling for.

That is until the signal to inject more fuel (as the driver has control now and has the pedal down) comes into play, hence the sudden take off as it suddenly gives fuel/air control back to the driver and it's all wide or near wide open as the driver is trying to compensate.

Basically, the car's ECU is trying to control the initial pull away, but driver input is buggering it up!

Now I'm wondering, as the clutch switch is either a closed or open signal (depending on the pedals position) disconnecting it should not produce a DTC, the ECU would just think it's in open (clutch up postion) position and allow the driver control over the fuel/air via the accelerator pedal when pulling away.

This would then stop the ECU- clutch switch adjusting the idle/air/fueling when the clutch pedal is raised and may stop the problem.

If I get the chance before I have to hand back this loaner, I'm going to check what is attached to the clutch pedal and compare it to the Mrs's Panda.
I might have a go, if I can find it at disconnecting whatever clutch switch on her Panda, see if it makes a difference.
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Last edited by Goudrons; 11-07-2014 at 08:22.
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Old 11-07-2014   #34
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Re: 2014 Fiat 500 1.2 acceleration issues

You might not be far off with this theory. The other night I removed the air filter box to get a better look at these supposedly missing bolts.
When I put it back on I forgot to refit the small hose on the back of the air filter box, which I'm assuming looking at it, is the idle air bypass. The pull off performance was a hell of a lot smoother and the acceleration was significantly better. So much so that I knew something had been disturbed, when I checked found I'd missed the hose off. I've had to re-attach as I wouldn't want to drive with it disconnected, but It did make me check that the spigot on the air filter box wasn't clogged (unfortunately clear so not the problem).
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Old 11-07-2014   #35
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Re: 2014 Fiat 500 1.2 acceleration issues

Check for a collapsed hose perhaps? They also crack nicely too
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Old 11-07-2014   #36
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Re: 2014 Fiat 500 1.2 acceleration issues

Quote Originally Posted by 306maxi View Post
Check for a collapsed hose perhaps? They also crack nicely too
Hope not its only a couple of months old (panda by the way). Collapsing hose is a thought though.
How low do you think the pressure in the air filter box drops by when you open the throttle? could this be stalling the air flow to the Idle bypass?
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Old 11-07-2014   #37
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Re: 2014 Fiat 500 1.2 acceleration issues

Right, just been out to the carpark (luckily, the Mrs works at the same place as me, Joy eh!)

The 63 plate 500S loaner idles smoothly, the clutch pedal has no effect on idle, whether up or down.

The 14 plate 1.2 Panda increases the idle somewhere between 200 and 250 rpm with the release of the clutch pedal.

Oddly I can actually hold the clutch pedal halfway up and keep the rpm up from around 750-800 rpm to around 1000 rpm quite easily.

On the 1.2 Panda the ECU via the clutch switch is taking control of air/fueling when the pedal reaches a certain position, then releases it when either fully up or fully down.
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Old 11-07-2014   #38
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Re: 2014 Fiat 500 1.2 acceleration issues

Quote Originally Posted by Goudrons View Post
(luckily, the Mrs works at the same place as me, Joy eh!)


On the 1.2 Panda the ECU via the clutch switch is taking control of air/fueling when the pedal reaches a certain position, then releases it when either fully up or fully down.
Where do you think its controlling the air input- at the throttle body or at what appears to be a small electric valve at the base of the inlet manifold where the bypass hose fits to?
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Old 11-07-2014   #39
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Re: 2014 Fiat 500 1.2 acceleration issues

The input comes from the clutch pedal.

That signals the PCM (engine ECU) that the clutch is in a certain position.

The PCM then opens the throttle bypass, and it's also probably adding fuel via the injectors at the same time, though without monitoring the fueling it would be hard to tell.

I guessing clogging the throttle pedal at this time is causing the issue.

Only a theory but if the main TB is opened (is it still cable operated?) and the ECU hasn't yet relinquished fueling control, there won't be enough fuel to air, so it's staved of fuel.

Funny how other manuacturers manage it, like I wrote before, my X Type diesel increased rpm with the clutch, but only in gear, but then again it would have done this with fueling alone, as there isn't a TB on a diesel.
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Last edited by Goudrons; 11-07-2014 at 14:12.
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Old 11-07-2014   #40
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Re: 2014 Fiat 500 1.2 acceleration issues

Quote Originally Posted by Goudrons View Post
I've just been reading up on some of these thread about the acceleration issues.

The Mrs 1.2 Panda Lounge (built Feb 14) has this flat spot issue.
The 63 plate 500S loaner (built ??) I have at the moment doesn't.

What I have noticed if you sit with the Panda idling, releasing or drepressing the clutch increases the RPM.

With the 500S, the clutch action has no effect on idle speed.

I know modern cars will often adjust idle when it detects a raising clutch to prevent a stall, my 2.0D Jag did this, but it seems Fiat efforts to do this seem to have caused an issue.

This is just a guess, (as I do drive her 1.2 and seem to drive around the problem) the flat spot - sudden take off appears to be a problem if you input a little too much throttle when raising the clutch.
Raising the clutch without throttle input to get the car rolling, then accelerating doesn't appear produce the same effects.

As I understand it, the throttle bypass would be controlling idle and is being signalled via the clutch switch to open up more when the pedal is raised, so opening the throttle body to allow more air in while the bypass is wide open controlling engine speed may be bogging the engine down due to more air entering that it's fueling for.

That is until the signal to inject more fuel (as the driver has control now and has the pedal down) comes into play, hence the sudden take off as it suddenly gives fuel/air control back to the driver and it's all wide or near wide open as the driver is trying to compensate.

Basically, the car's ECU is trying to control the initial pull away, but driver input is buggering it up!

Now I'm wondering, as the clutch switch is either a closed or open signal (depending on the pedals position) disconnecting it should not produce a DTC, the ECU would just think it's in open (clutch up postion) position and allow the driver control over the fuel/air via the accelerator pedal when pulling away.

This would then stop the ECU- clutch switch adjusting the idle/air/fueling when the clutch pedal is raised and may stop the problem.

If I get the chance before I have to hand back this loaner, I'm going to check what is attached to the clutch pedal and compare it to the Mrs's Panda.
I might have a go, if I can find it at disconnecting whatever clutch switch on her Panda, see if it makes a difference.
Great post there.

I've been meaning to post about the clutch switch/idle speed as I think it might be related to the problem (if not necessarily the complete cause).

Our old 1.2 500 (59 plate) never used to change its RPM when you dipped and released the clutch. However, our 12 plate 1.2 Panda does do that, and it's exactly how you describe.

The two main changes I have found with the Panda compared to the 500 are as follows:

1. It is much easier to reverse the Panda into a space without applying any throttle; you can just bring the clutch up to the biting point and the car's revs will rise a little bit (as you say around 250rpm). On the 500 you'd have to be very disciplined with clutch control if you didn't want to stall it without applying any throttle.

2. However, the flip side is that if you try to reverse the Panda up a slight incline, it struggles and you really have to give it some welly. I really used to have to work it hard to get it up our drive in our old house, even now it has got 30k on the clock now and has never really improved in this respect. The 500 never had any issues here.

Regarding disconnecting the clutch switch; I can't confirm 100% that it doesn't produce a fault code, but our clutch switch broke off in 2012 and all it did was make gear changing rougher and the car a bit jerky if you tried cruising in gear without applying throttle. See my thread from back then:
https://www.fiatforum.com/panda-iii/...ch-switch.html
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Old 11-07-2014   #41
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Re: 2014 Fiat 500 1.2 acceleration issues

i cant believe they got the FIRE engine through euro 6

origins date back to the 1980s!
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Old 11-07-2014   #42
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Re: 2014 Fiat 500 1.2 acceleration issues

Quote Originally Posted by RobW View Post
i cant believe they got the FIRE engine through euro 6

origins date back to the 1980s!
Yeah my engine does feel a bit 'old school' I think they didn't manage with the 1.4 though, they have discontinued it anyway. I am with the Euro 5 1.4 emitting 135 g/km without S/S (with ss its 130).
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Old 12-07-2014   #43
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Re: 2014 Fiat 500 1.2 acceleration issues

Probably irrelevant, but our 2012 500 TwinAir and my 2013 MiTo JTDm both raise the revs slightly as you start to let the clutch up. It seems it's not a new idea to Fiat, but just to the 1.2 engine, particularly in the 500.

Quite why it's causing problems in the 1.2, and most importantly only some 1.2s, is baffling. And all the guess work having to be done by owners and not Fiat, is appalling.
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Old 16-07-2014   #44
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Re: 2014 Fiat 500 1.2 acceleration issues

I just had a phone call from Fiat Head Office. They wanted us to meet with a main representative at our local dealers, to discuss the car and to talk though with us how to drive it. I told them that they had already had the car back twice and they had told us that they couldn't do anything. The last remapping changed the position at which the clutch recognition came in, but since then it has continued to change and now revs up immediately the pedal comes off the floor. Now the engine sometimes tries to rev constantly when in 1st or 2nd gear, it doesn't want to idle, sometimes it surges. They wanted to have the car, but I told them that they are not having it until DVSA have had a chance, and that there were other people with the same problem and I want to get something for everyone affected not just me. I was then told they would close my file in that case.

I have been in touch with other owners who are also contacting DVSA and other motoring organizations and press. I have had some advice on the technical side and from this I have concluded that it is very unlikely that there is an easy fix, its probably back to the drawing board time.

I am also insulted by the 'we'll teach you how to drive it' bit. I have a lifetime's experience of driving a wide range of vehicles and machinery of all ages, sometimes doing recovery in very bad conditions where safely is paramount. I can adjust the way I drive to respond to the car's changing symptoms, the point is it shouldn't be necessary!
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Old 16-07-2014   #45
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Re: 2014 Fiat 500 1.2 acceleration issues

Why don't you want to let them look at it? How are they meant to sort it otherwise?
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