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Old 2 Weeks Ago   #1
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idle problems when hot

OK, so my Grande Punto runs really well, but when it is hot and I have to stop at lights, the idle is really slow and it feels like the car is miss firing. I had the machine plugged in for me and was told there are no fault codes showing, so it can't be a miss fire.
I have tried disconnecting the battery lead since then, and it has made no difference.
Does anyone know if it will have an idle speed sensor? If so, could this need replacing?
I am really in the dark here, and anything I have said is based on what other people have suggested!
Can anyone help me?
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Old 2 Weeks Ago   #2
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Re: idle problems when hot

Please search the forums before posting, thank you. Many similar threads exist already. People are just too kind to keep answering the same old stuff over and over again. Google also knows plenty of things.

Have the car serviced fully with new filters, spark plugs, oil first if it hasn't already been done. Sometimes it's a dirty map sensor with/without intake leaks on the hoses.
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Last edited by eeeno; 2 Weeks Ago at 15:28. Reason: Map sensor added
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Old 2 Weeks Ago   #3
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Re: idle problems when hot

Most problems are just neglected maintenance over time.

Combinations like (skip any 2, 3 or 4 of those, and the problems may appear):
- old spark plugs,
- old oil,
- old filters (air, oil),
- bad/clogged PCV system ("breather hoses"),
- valve clearances in 8-Valve engines (most neglected thing ever),
- old timing belt and or coolant pump, or VVT malfunction (because of dirty oil),
- fuel pump (starting with dirty inlet in the tank),
- something electrical (sensors - MAP, lambda, temperatures, bad ground - "earthing points", bad battery, bad alternator - because of improper water drain in early years of production).

Address those things folks and you should be fine. And SEARCH (multiple threads on: no power, no start, rough idle, engine stalling etc.).
Plus, the Guides section: https://www.fiatforum.com/grande-punto-guides/.
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Last edited by GrandePunto PL; 2 Weeks Ago at 20:39. Reason: ...SEARCH forums, and read the Guides.
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Old 2 Weeks Ago   #4
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Re: idle problems when hot

Quote Originally Posted by eeeno View Post
Please search the forums before posting, thank you. Many similar threads exist already. People are just too kind to keep answering the same old stuff over and over again. Google also knows plenty of things.

Have the car serviced fully with new filters, spark plugs, oil first if it hasn't already been done. Sometimes it's a dirty map sensor with/without intake leaks on the hoses.
Sorry if you think I should have looked elsewhere first. I have looked through the forum and couldn't find anything that helped. I have just bought the car, which came without any history.
As with any car I have ever bought, the first job was a full service.
I have also had a new cambelt and water pump fitted.
The only thing that came with the car was a pile of receipts for a new clutch, battery, starter motor, alternator belt and exhaust.
As the problems do not appear until it gets hot, it was not apparent on the test drive that there were any issues.
I have not owned a Fiat for about 40 years, when I had to let my 500 go.
I have bought a haynes manual, but its really no help unless you know what the problem is. Thanks .
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Old 2 Weeks Ago   #5
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Re: idle problems when hot

If nothing of the usual fixes works, it might be the air intake manifold gaskets, they need to be replaced.
Check this post, maybe you can find something that helps, my post is no. 36
https://www.fiatforum.com/punto-ii/4...ic-load-3.html
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Old 2 Weeks Ago   #6
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Question Re: idle problems when hot

Quote Originally Posted by suel View Post
I have just bought the car, which came without any history.
So you should go through the maintenance list like example one (mine) above. Step by step, of course, not everything at once.
Quote Originally Posted by suel View Post
As with any car I have ever bought, the first job was a full service.
Wanna bet it wasn't "full"? Define "full". Also, did you know that most mechanics are incompetent?

PS
Note, that Fiats (in general, all models) are little bit rough sometimes, naturally (maybe there's nothing wrong). People are oversensitive. Don't compare Fiat to other brands. Is it shaking brutally whole car at idle, or just a little bit vibration from time to time (and you feel it only on steering wheel)? Does it stall (or almost) when you start moving?
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Old 2 Weeks Ago   #7
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Re: idle problems when hot

You can try searching "low idle speed causes".

How about emissions test values from MOT, so that we could keep guessing a little more?

But any DIY guy would do following:
  • check spark plugs &leads and change if necessary
  • change ignition coil if it had never been changed before and car has more than 140 miles on clock
  • blocked engine air filter, check/change
  • clean throttle body, check that air filterbox sits properly
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Old 2 Weeks Ago   #8
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Re: idle problems when hot

Thanks for your reply, I did the service myself, so I know all the basics were done, and I put a new set of ignition leads on at the same time.
The problem is noticeable as soon as it gets hot, its more than just a slight roughness at idle, which I would get used to.
I now have a problem on acceleration where it feels like its running out of petrol and then clears.
So am now looking at more of a fuel issue. will start with good clean of throttle body and see what happens.
Thanks for the advice, it is much appreciated.
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Old 2 Weeks Ago   #9
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Re: idle problems when hot

I did the service myself, and also put on a new set of ignition leads. The car is on 96,000 miles, so I also had the cam belt and water pump done.
I appreciate that all cars feel different, but its a roughness you can feel through your feet, and it has now developed into a problem when at higher revs too. It feels like its about to run out of petrol, so am thinking more a fuel problem.
Will start with a good clean of the throttle body and see what happens.
Thanks for your help, am glad of any suggestions, especially from people who know Fiat better than I do!
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Old 2 Weeks Ago   #10
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Re: idle problems when hot

What specific model/engine in your GP?

Have you used MES/AlfaOBD to pull up live running data not just codes?
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Old 2 Weeks Ago   #11
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Re: idle problems when hot

Have you considered the problem being a clogged exhaust, for example rear silencer? Very common on cars of this age. Also clogged catalyst would cause running issues that's why I would take a look at the emissions report. Also a leaky head gasket makes engine run roughly.

MES and appropriate obd equipment will pay itself back. Live data shows fuel trims, fuelrail pressure and much more. I'd clean the map sensor and see from live data if intake manifold temperature was correct. Crankshaft, camshaft sensors may cause similar problems when hot. For example difficult starting when hot.

But ECU monitors all the sensors and when there's no codes, no reason to start changing any. Good luck!
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Old 2 Weeks Ago   #12
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Re: idle problems when hot

1. Every-time you swap timing belt, check also valve clearances (all 8V petrol engines).
2. We still don't know which engine. And year ("plate" as you say in tha UK). Is this a joke/prank? This thread should be erased.
3. Throttle body? Leave it alone. It's the last thing on the long checklist of neglected things in your car. Unless it's damaged, visibly. Or totally clogged.
4. Check fuel pressure. Gasoline engine = about 3,5 bar (small drop is acceptable, let's say 0,1-0,3 bar).
5. Check the vacuum, with real mechanical gauge (stick it to the small breather hose, which goes under the throttle), old-school, no one does that anymore. Petrol 8V should do about -0,7 bar at idle (or absolute +300 mbar, and MAP sensor reading via OBD2+MES should be the same).
6. As for vacuum, intake leaks, breather hoses (PCV system), there is also EVAP system, solenoid valve can be sticky (Open or Close) or leaky (easy to bump it and it will not seat properly in place).
7. Ignition cables? OK... What about sparkplugs?
8. You are "glad"...but you don't really listen, you don't read and do what people suggest.
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Old 2 Weeks Ago   #13
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Re: idle problems when hot

Let's just try to be nice. However these "My Fiat runs poorly, any suggestions? " type of threads should be cleaned and pinned under one thread "Engine running poorly".

People are trying to help but these threads are almost identical to each other. So I understand the frustration. There could be troubleshooting wizard before opening new thread or it could suggest threads that already exist.

I think some automation could help here. People just need someone to point them to the right direction.
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Old 1 Week Ago   #14
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Re: idle problems when hot

It's a lot of manual work (cleaning, joining few threads to one...). I was one of the admins of big Renault forum and I solved these "cleanups" on daily basis. There was so.much work that we (admins) distributed load and I was for example responsible for Megane2, Megane3 and Fluence sections, other admin for Clio and Laguna sections and so on. But yes, real enthusiasts can do it also here. And in each section, common (general) issue threads were always "pinned" at the top as first
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Last edited by Rado77; 1 Week Ago at 06:53.
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Old 1 Week Ago   #15
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Re: idle problems when hot

Most newbies will just ignore pinned threads and start a new one anyway.
Moderators do nothing about it.
If you point that out, you are the bad guy.
That's how most forums in the world work (politically correct "safe spaces" - most content is garbage, but it's nice and polite).

Starting new thread without doing any research should be brutally punished.
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Last edited by GrandePunto PL; 1 Week Ago at 04:12. Reason: Politically Correct "safe space" for losers, SJWs.
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