The problem I have is a tricky one . When the engine starts initially (cool), it idles fine and will slot into 1st and reverse fine , the rev counter is steady at 850 -900, as it warms up a matter of 3mns say the rev counter will jerk up and down from 900 to 1050 .You try a gear and it immediately cuts out. I f you let it idle as well without doing anything it will cut out.
If you try and keep the revs high , say 1200 and slot a gear it will also cut out , giving the impression a reasonable amount of drag from the clutch . This could be normal as the speed indicator will think that were off and running.
My theory is that the speed sensor/transmitter on the back of the gearbox is telling lies to the engine ecu, I had it tested at the local Fiat garage and they said it was ok. (not convinced).
Of course it could be faulty wiring , but again nothing showing except the diag says there is an intermittant fault in a Can line to a Microprocessor 2 , what ever that is . I'm about to clear all these faults as I have been trying different things to eliminate things.
Overall no real evidence of decent fault codes .

Is there another speed sensor feeding the rev counter or is the gearbox one the only one.
I am talking selespeed on a 07 plate Panda 1.2 8v.

I could be numerous things but anything that plays up when hot (as you say) suggests a sensor of some sort.

Check the crank position sensor as they can work ok when cold but fail when hot and do not raise a fault code on the ECU. Basically, the ECU acts as if the engine stalled so no fault raised.

It's a guess of course, but they are not costly.
https://www.ebay.co.uk/sch/i.html?_...fiat+panda+1.2+crank+position+sensor&_sacat=0

Ok , I changed that a week ago, with no result, it was a Delphi product , so should be sound . The very first fault that came up on the dash was a transmission fault , but not seen since.
Maybe should have stuck to whatever Fiat use . The Gearbox on was Magnetti Marelli , Ill check

Sorted!
Forgot to say , the crank was mistakenly diagnosed as the initial problem, more a transmission fault, talk about leading you down the garden path !
As it happened it didn’t cure the idle and intermittent starting , it was the fuel pump. Then changed that and still the idle problems.
You can work the rest out from that.

boatlon said:

Sorted!
Forgot to say , the crank was mistakenly diagnosed as the initial problem, more a transmission fault, talk about leading you down the garden path !
As it happened it didn’t cure the idle and intermittent starting , it was the fuel pump. Then changed that and still the idle problems.
You can work the rest out from that.

Click to expand...

Yes but, what was the real problem?

As I said , it was the fuel pump, the crank sensor was misdiagnosed as it started the car etc but would not idle before as well . The sensor remained in thinking it was ok , then the fuel pump was found to faulty, this was changed as it was obvious this wasn’t working properly.
Meanwhile idle problem still there, as , never thought the new sensor was at fault.

It's unusual for fuel pumps to cause a weak idle so no surprise it took a while to find. I was confused because you had said, "Then changed that (fuel pump) and still the idle problems."

Crank sensors are cheap enough to change anyway but well done for getting it sorted.

Yes , a bit unusual, the motor within the unit would run then stop , it sounded rough at the same time , a s/h one from a breaker showed up the difference. Sometimes you can think of the more complicated route when its staring you in the face !

To be fair the fuel pump would not be most people's first place to look. They are reliable and worn pumps tend to struggle when driving hard rather than going fluffy at tickover speeds.

Anyhow, glad you got it sorted.

As a question - how is the pump controlled? In the old days, they just ran full bore but today they are throttled by electronics. Is that done with the ECU or is there a separate controller?