Hi,

Im posting on behalf of my not too computer literate dad, he has an 07 reg gp 1.2 active and there is a noticeable issue with the accelerator when you release it. At low revs all is ok but when you are above maybe 2000 rpm or so (i might be a bit off there but if its important i can check) and release the accelerator pedal there is a very distinct and sudden slow down and drop in revs, making for very jerky gear changes etc and its noticeable to everyone in the car, not just the driver. This happens at higher revs no matter how gently you release the accelerator, there is always this sudden drop and a jerkiness to it. Any ideas what this could be? He's going to get it looked at as soon as he can but its always good to have a bit of an idea rather than going in blind.

If you release the accel pedal and press clutch very fast (so there's no rpm reduction or fuel cut engage) what is the behavior of the car?

Thanks for replying . Ill have to ask and get back to you on that one.

OK, I've just give him a quick call but it was a bad line so was hard to get my point across.

Basically, he says it happens with higher rpm and happens both when you release the accelerator eg in slow moving traffic and when changing gear, thus depressing the clutch straight after releasing the accelerator.

There is no jerk when you depress the accelerator again after changing gears and with low rpm (around 2000 or less he says) it seems smooth across the board. He says its like a sudden slow down and the rpm drops suddenly as well although that's not a particularly noticable drop, people in the car with him notice it straight away as it throws you forward slightly.

I've just remembered, he's also having a vibration noise issue which I think is down to the rubber on the air intake pipe bracket disintegrating, I've said ill have a quick look for him this weekend because a mate of mine also had that issue with his gp and the sound is seemingly the same. It couldn't be something to do with that could it, there might be some damage leading to a clogged air filter or something? Probably not but I thought I'd mention it cause i've no idea really

Ok so the problem is noticeable whenever rpm > 2000 and not accelerating with gear engaged.

So if he change gear lets say a downshift from 4th to 3rd resulting in an rpm increase from 2000 to 3000 the jerking (slow down?) is noticeable if accel pedal is not pressed until ~2000 and then it's smooth again?

You basically get the sudden slow down when you fully release the accelerator pedal unless you are below 2000 ish rpm in the lead up to doing so. This is the case whether accelerating and changing up, decelerating and changing down (although you probably wont be on the accelerator in this case anyway) or just rolling in variable speed traffic where you are on and off the accelerator. It seems independent of gear or speed.

Its usually just the one lurch with maybe a bit of an aftershock or two if you will only at the point of releasing the accelerator, never any other time and it happens no matter how gently you release the accelerator.

Apologies if im not being clear, its kind of hard for me to explain and I appreciate your time.

stanjefferson said:

I've just remembered, he's also having a vibration noise issue which I think is down to the rubber on the air intake pipe bracket disintegrating, I've said ill have a quick look for him this weekend because a mate of mine also had that issue with his gp and the sound is seemingly the same. It couldn't be something to do with that could it, there might be some damage leading to a clogged air filter or something? Probably not but I thought I'd mention it cause i've no idea really

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No I don't think it's related. Check intake hose pipe as you said it's a classic problem, inner fender, engine mounts etc.

stanjefferson said:

You basically get the sudden slow down when you fully release the accelerator pedal unless you are below 2000 ish rpm in the lead up to doing so. This is the case whether accelerating and changing up, decelerating and changing down (although you probably wont be on the accelerator in this case anyway) or just rolling in variable speed traffic where you are on and off the accelerator. It seems independent of gear or speed.

Its usually just the one lurch with maybe a bit of an aftershock or two if you will only at the point of releasing the accelerator, never any other time and it happens no matter how gently you release the accelerator.

Apologies if im not being clear, its kind of hard for me to explain and I appreciate your time.

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Ok I'm just trying to understand if it's engine problem or engine/gearbox mount problem.

No check engine light right?

cmosfxx said:

No I don't think it's related. Check intake hose pipe as you said it's a classic problem, inner fender, engine mounts etc.

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Ok, yeah, I'll have a quick look over the weekend, hopefully its a simple fix for that.

cmosfxx said:

Ok I'm just trying to understand if it's engine problem or engine/gearbox mount problem.

No check engine light right?

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Nope, nothing like that. There's no audible clunk or anything by the way but it did have a new gearbox fitted about 2 years back but the problem has only occurred in the last few weeks/months so I didn't make the connection till you said that.

No there will be no noise if mounts are gone on GP. It's not so easy to check but... test for engine play while the car is parked with handbrake engaged. Open the hood and tell someone to quickly release the clutch (not all the way we don't want the engine to stall but you can feel when to press again back) with 1st speed engaged and foot on brakes also. Then test on reverse too.

Inspect engine movement. There will be some and it's OK, check gearbox side too.

Also do this test:

If you release the accel pedal and press clutch very fast (so there's no rpm reduction or fuel cut engage) what is the behavior of the car?

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The tip is to engage clutch very fast before you get your foot of the accel.

Then inspect engine rpm.

Post results

Personally I'd check all the obvious things first like the pipes that run from the air box and the plugs and check for engine codes with an ODB reader

Try Cleaning the throttle body and then do throttle relearn (this must be done after cleaning throttle body )


https://www.fiatforum.com/grande-punto/262685-1-2-wont-idle.html

Cheers for the input guys, ill have a look at that over the course of the weekend and see what I find.

OK, had a look at the engine/gearbox movement, there definitely is some obviously but i'm not sure if its too excessive, a couple of inches either way, maybe 3 at a push. is that excessive? If you try to move the engine by hand it will only go a cm or so and doesn't move/wobble at all when idling.

He's just gone out in it now so he's going to have a look at what you said if he can, unfortunately I couldn't go with him to have a look myself so will have to maybe try to get out later tonight or tomorrow.

I've checked all the hoses/pipes etc but nothing stands out and from what I can see of the mounts there is no visible issues but obviously that doesn't tell you much. Ill have to wait until Monday to check for any engine codes showing up as I don't have an obd reader but a mate does.

Is there a guide anywhere to help with cleaning the throttle body? With it not being my car I don't want to mess about unless i'm 100% sure

I managed to sort the rattle out at least, the air intake pipe was completely out of the mount so i've popped it back in as the rubber looked ok and put a cable tie around it to stop it coming back out.

OK, this is odd, when he got back, he said it wasn't doing it at all, so Ive just been out in it myself and it seems absolutely fine. I literally could not get it to happen once and also there seems to be an improvement in terms of power at lower revs, it seems harder to stall it and the engine resistance when going downhill etc is better and I've no idea why its like this

I had a go last week and could not for the life of me get it to NOT jerk around when releasing the accelerator and this time nothing I did could get it to happen in any way. I also stalled it a couple of times last week and this time it seemed like it could set off much easier. Im very confused at this point :roll eyes:

The accelerator does seem a little harsh initially in comparison to other cars I've driven but nothing to write home about.

aaah classic fiat car! auto-fixing is one their features

If you stalled it easily then consider a MAP+throttle body cleaning

Yeah, its not the first time its fixed itself either

Ill consider that at some point, will keep an eye on it for a while just incase it changes its mind. Thanks for your help mate

Accelerator pedal check the TPS %


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I seem to be having the same problem, did you manage to sort it and what was it if so?