Technical Raising RPM by itself

[subalfa]

Hi Guys!

I have searched a lot about my problem but can't find the same issue.
2001 Punto 1.2 V8 issues:

- starts properly and idling normal below 1000. When I press the acc. pedal a little and hold that position the rpm is raising as if keep pressing continuously.

- every time when I press the clutch and release the acc.pedal above 2000rpm it seems the rev stuck for a second.

- in the traffic or when I can move only by meter by meter sometimes (never know when and why) the rev stuck and/or raises itself above 3000. If I press the acc.pedal in this case it raises even higher and stuck like 5000. I have to turn off in this case. If I turn the key quickly the engine continue the work without "ignition" like I wouldn't have turned it off but drop back on normal idle rev.

- also in the traffic sometimes it starts to raise the rev by itself above 3000. Before it happens the idle begins to waiving between 700-900.

The Throttle Body is clean and I have a new TPS. No Engine light at all and computer can't find any error.

At normal driving never happens anything.

Have you ever had this kind of problem? Thanks in advance.

 

[Barchetta Bloke 440]

This is the Barchetta section of the forum not Punto....

 

[subalfa]

I know and sorry about that but don't know how to remove since I posted it into the right place too.

 

[eramosa]

Sorry, but sounds like a faulty ECU. The Map (manifold absolute pressure) sensor reports total air intake volume, MAF (mass air flow) dictates fuel/air ratio for optimum burning, the TPS (throttle position) basically reports FT (full throttle) condition or not. These sensors report conditions but the ECU acts upon them.

 

[Cribus]

This will be no help at all but years ago I had an old 1.2 Punto which used to rev by itself at idle, just like a ghostly boy racer had taken control of the car. This habit caused much amusement one day when I had to pull up at some lights behind a police car. I traded the car in before I could work out what the problem was. The Barchetta has never done it so one answer would be to get a B instead, but there may be more straightforward options.

 

[subalfa]

I connected a computer to the car and the diagnostic software showed the following:
Sometimes lost the tps signal along with the rpm BUT on the dashboard the unit shows the rpm properly. The two signal disappear and come back at the same time. Are you sure it's not a sensor fault (I don't know which one but obviously not the tps since it's new)?

 

[Peter Pick-Up]

Does the 8V engine have an Idle Air Control valve ( IAC) if so, it's probably broken.
A stuck valve causes erratic idle...