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Old 16-09-2019   #1
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Talking Rough Idle / Misfire - When car is warm?

Hey guys I have a grande punto tjet 1.4 2009.

I have noticed that when my car is warm (upto temperature) there is a feeling of a shudder, grumble underneath me when the car is sitting stationary and idling.

Now it is not a fierce shudder that makes you feel if car is shaking apart, but it is definately there. It does it to a steady pace - so it fades in and out doing it at a constant tempo that you can guess when it is going to do it, its not random in and out all over timings, but as soon as you drive away it goes.

Added info: (not sure if linked but just providing)

1) When i start the car up from cold the rev counter / needle is high at about 1100 revs for about 30 secs and then levels out to about 800 revs. I have the most MINOR HAIRLINE of cracks in one of the air hoses attached on the engine cover - So not sure if that is causing high initial revs

2) When you can feel the shudder, everything else is normal, the rev needle isn't fluctuating or anything you can just feel. If it wasn't doing this shudder / grumble you woundlt think anything is wrong with the car.


thanks in advance
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Old 16-09-2019   #2
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Re: Rough Idle / Misfire - When car is warm?

Any (small) leak at the lambda sensors or at exhaust flex pipe ?
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Old 16-09-2019   #3
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Red face Re: Rough Idle / Misfire - When car is warm?

Quote Originally Posted by Bernievarian View Post
Any (small) leak at the lambda sensors or at exhaust flex pipe ?
Not too sure,as i have never checked to see if they are blowing but 02 sensor or on the exhaust. So if it was this would cause the juddering feeling when car is upto temp?
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Old 16-09-2019   #4
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Re: Rough Idle / Misfire - When car is warm?

"1) When i start the car up from cold the rev counter / needle is high at about 1100 revs for about 30 secs and then levels out to about 800 revs. I have the most MINOR HAIRLINE of cracks in one of the air hoses attached on the engine cover - So not sure if that is causing high initial revs"

Higher RPM when cold is normal.

Could your judder be worn engine mount?
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Old 17-09-2019   #5
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Re: Rough Idle / Misfire - When car is warm?

Quote Originally Posted by SRafferty View Post
"1) When i start the car up from cold the rev counter / needle is high at about 1100 revs for about 30 secs and then levels out to about 800 revs. I have the most MINOR HAIRLINE of cracks in one of the air hoses attached on the engine cover - So not sure if that is causing high initial revs"

Higher RPM when cold is normal.

Could your judder be worn engine mount?
Hey rafferty. Thanks for input. I'll give this a check but I doubt it is. If it is its going to be one of those it looks fine but could it still be bad type of things lol. Is there anything other than a visual check that you can do to check if the mounts are worn?
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Old 19-08-2021   #6
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Re: Rough Idle / Misfire - When car is warm?

Hi there.

I came across this post when searching for the exact same problem in my 2009 Alfa Mito which I believe uses the same 1.4tb (120hp) Fiat engine as the one in your car.

Did you ever get to the bottom of what was causing the rough/lumpy idle? Mine also only happens when the car is up to temperature, and only noticeable when stationary.
Switching on the air con seems to stop it happening.

Any help would be appreciated! Thanks
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Old 19-08-2021   #7
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Re: Rough Idle / Misfire - When car is warm?

Sound like an airleak on the vacuum hoses or blocked pcv hose or crack on it. Very usual! If you're not familiar with any of this stuff, then take it to a garage or have a mechanic friend to fix it for you.

If you intend to fix it by yourself, then there's plenty of guides online and then open the bonnet....

There are hoses that are attached on the air filter box just above the throttle body. Just check and/or replace all of them. Then there's brake booster hose and evap.
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Last edited by eeeno; 19-08-2021 at 17:21.
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Old 20-08-2021   #8
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Re: Rough Idle / Misfire - When car is warm?

Thanks for this!

You're the second person to have said it's likely to be a vacuum leak.
It seems to happen more after the engine has had a bit of boost from the turbo/higher revs..

I'm not particularly mechanically minded but I'll take a pop at it.
Off to YouTube I go.

Thanks again for your input
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Old 20-08-2021   #9
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Re: Rough Idle / Misfire - When car is warm?

Hey Pal,

Apologies for not getting back, in regards to judder, I had a few things that to check, so before this post, I noticed my timing belt was loose. Innthe end changed that (a whole saga with it but was a great learning curve, done a thread in it hear "timing belt too loose or too tight" search for). This seem to solve.my issue, but then I noticed a slight judder alittle while back, but I just left it as car wasn't being used and decide to inspect when had.more time. Last week I happened to be doing my service, oil , gearbox oil and spak plugs etc. As I was changing one of the plugs I noticed one was loose, didn't take anything to undo and I'm thinking this maybe the issue, car is running how it should at the moment .

BUT I do have some light cracking on some breather hoses, that I need to change and I think I have a worn engine mount. So I'm gnasee how I get on, but if it comes back it will be surely a possible leak or mount.
Quote Originally Posted by mdotp View Post
Hi there.

I came across this post when searching for the exact same problem in my 2009 Alfa Mito which I believe uses the same 1.4tb (120hp) Fiat engine as the one in your car.

Did you ever get to the bottom of what was causing the rough/lumpy idle? Mine also only happens when the car is up to temperature, and only noticeable when stationary.
Switching on the air con seems to stop it happening.

Any help would be appreciated! Thanks
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