Technical STILO 1.6 Throttle Problem

Currently reading:
Technical STILO 1.6 Throttle Problem


New member
Oct 2, 2007

I have a 2004 Stilo MW 1.6 with 41000 miles. My car has developed a dangerous problem whereby it randomly and occassionally fails to respond to the throttle regardless of speed. However, if the throttle is allowed to return to the highest position it then responds normally. Can be very dangerous when no accelleration occurs in busy traffic or leaving a junction. The car was connected to an independent Fiat specialist's diagnostic kit and a potentiometer problem was diagnosed. The accellerator pedal and potentiometer were replaced at a cost of £150. Problem still there. Turns out Stilos have 2 potentiometeres and second one temporarily replaced but problem still there. Car taken to main dealer - no diagnosis and £100 bill for diagnostic test even though no result! Has been off the road for a month now and is also in engine safe mode and displaying engine fault. Well out of pocket and main dealer not interested but suggests changing (expensive) parts, such as the ECU, just to see what happens. Can anyone help? Has anyone else experienced this fault? Car has FSH, has had no dramas and is well looked after. Getting desperate as affecting ability to get to work and earn money to pay for repairs!! Cheers - Flashpaddler
Bit of a bitch this one so do a search and you may unearth previous ramblings. Obviously the fly by wire communications is interrupted between the gas pedal and the throttle. As you've found, there are two potentiometers in the gas pedal, one for use and the other for reference but these hardly ever seem to be the problem as it's in a nice dry environment apart from your sweaty feet:)

Ok so the comms go to the ECU which then tells the throttle when and how far to move. This also has twin tracks or potentiometers for the same reason only these are on the receiving end. A poor contact at the throttle valve connector will break the comms and this connector would be my first port of call with contact cleaner as this is a not so nice enviroment for electrics.
throttle body removal.JPG

Intermittent faults like this one are a real pain, but with the right equipment you can see if the gas pedal or throttle position potentiometers change resistance evenly throughout their full range with no jumps or dead spots.

When the throttle valve loses the plot of what to do you often need to do a throttle learning procedure so it knows where it is. Again do a search and it's all explained
A bit confused as to why you started with a Fiat specialist garage and ended up at your main dealer :confused:

Did the Fiat garage have access to Examiner (the better ones do) ?

thank you very much for taking the time to post such a comprehensive reply, it's very much appreciated. I think I am now at the point where a new ECU is required:cry: . I took my car to our local independent Fiat specialist simply because they are very, very good. They have diagnostic kit but it is not as comprehensive as a main dealers and they don't see the same volume of cars. Therefore, when a very unusal fault appears and all other options have been exhausted they take the car to the main dealer for advanced diagnostics. I have used them for 7 years and they take superb, personal care of us and only charge £40 an hour. Anyone with an Italian car who lives in or around Lincoln should give them a try as they are excellent mechanics - they just don't have all the resources of a main dealer, but this rarely matters.(y)
Seen this several times, there are a few causes, which I will list, some are obvious and some arent.

Accelerator potentiometer, this is on the pedal and is a double pot, there are 6 wires connected to it. I have seen these connector terminals open up and make a loose connection causing this problem.

The old D4 connector, the six wires go through this now famous connector block near the battery, again an opened up connector will cause this problem.

Throttle Potentiometer, this is the unit under the bonnet, it has six wires which go directly from the ecu. By now you know what you are looking for:)

The ecu itself, does not usually cause this problem BUT if the terminals are loose then they will cause the problem, check the terminals for cleanliness and make sure they are nice and tight.

If the fault is connected to the Accelerator pot (alot of people get throttle and accelerator pots muddled up especially non fiat techs) check the aircon pressure sensor. The sensor shares the same internal voltage distributor from the ecu as the pedal pots so any short or problem due to corrosion here can effect the voltage supplied to the pedal pot and cause this error.

Hope this helps
I appreciate that this is a very old post now but I have exactly the same issue on a 2008 bravo 1.4T. Very intermittent: can be trouble-free 3 out of 5 days. Really interested to know what fixed this issue