Hi,
I have a Fiat Punto 1.2 8v (2004) which sometimes has a really bad, rough idle.
Other than that the car runs fine, there`s no check engine light no excessive fuel consumption, starts quick, drives smooth.
The only problem is when the car is in idle and it`s RPM starts fluctuating noticably. Specially if I put some electric load on the car. Turning on the lights, using the power window.
I already tried to use various fixes with no luck. I went to two repair shops they didn`t find anything. I also went to an official Fiat Service Center. In the service senter they didn`t find the cause of the problem but reseted the ECU and said it fixed the problem. Well, it fixed for 5 minutes. After that it came back again. So I don`t really trust them anymore.
What I already tried:
- Checked the ECU for error codes with an ODB scanner (no errors)
- Reseted the ECU (by disconnecting the battery for an hour)
- Cleaned the throttle body
- Checked for vacuum leaks
- Replaced the idle air control valve (IACV) on the throttle body
- Replaced the whole throttle body form another car
- Replaced the battery
- Replaced the pre-cat lambda (O2) sensor
- Replaced the MAP sensor
- Replaced the spark plugs
- Replaced all ignition coils
I also bought an ODB scanner and checked the car with the Multiecuscan software but couldn`t find anything suspicious. I attach the Multiecuscan logs here. You can check it if you have the free Multiecuscan software. I mark the moment when the rough idle starts in the log. The image only shows the RPM but the log shows many other details as well.
View attachment Fiat Punto 1.2 8v 2004 - rough idle - multiscanecu log.csv.zip
Created a video which shows the whole problem. (turn on the captions on the video for details)
Do you have any suggestion what I should check? My next guess is the altenator because it happens more often under electric load.
I have a Fiat Punto 1.2 8v (2004) which sometimes has a really bad, rough idle.
Other than that the car runs fine, there`s no check engine light no excessive fuel consumption, starts quick, drives smooth.
The only problem is when the car is in idle and it`s RPM starts fluctuating noticably. Specially if I put some electric load on the car. Turning on the lights, using the power window.
I already tried to use various fixes with no luck. I went to two repair shops they didn`t find anything. I also went to an official Fiat Service Center. In the service senter they didn`t find the cause of the problem but reseted the ECU and said it fixed the problem. Well, it fixed for 5 minutes. After that it came back again. So I don`t really trust them anymore.
What I already tried:
- Checked the ECU for error codes with an ODB scanner (no errors)
- Reseted the ECU (by disconnecting the battery for an hour)
- Cleaned the throttle body
- Checked for vacuum leaks
- Replaced the idle air control valve (IACV) on the throttle body
- Replaced the whole throttle body form another car
- Replaced the battery
- Replaced the pre-cat lambda (O2) sensor
- Replaced the MAP sensor
- Replaced the spark plugs
- Replaced all ignition coils
I also bought an ODB scanner and checked the car with the Multiecuscan software but couldn`t find anything suspicious. I attach the Multiecuscan logs here. You can check it if you have the free Multiecuscan software. I mark the moment when the rough idle starts in the log. The image only shows the RPM but the log shows many other details as well.
View attachment Fiat Punto 1.2 8v 2004 - rough idle - multiscanecu log.csv.zip
Created a video which shows the whole problem. (turn on the captions on the video for details)
Do you have any suggestion what I should check? My next guess is the altenator because it happens more often under electric load.
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