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Old 05-08-2009   #1
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Looking inside the 1.4 12v Throttle Potentiometer / Position Sensor

Point of this thread:
The throttle potentiometer is not a serviceable part as it is calibrated from the factory. But if someone wants to have a try this thread will let them know what to expect.

Here we go
So many 1.4 owners seem to be suffering from similar problems at the moment. I found my solution in a replacement Throttle Body.

My symptoms where;
Erratic Idle.
Stalling.
stuttering/light kangarooing.
car acting like it had ran out of petrol.
engine braking while holding a steady pace.
Having to give a little throttle when restarting the car.
Having to give it lots of throttle to stop it misbehaving.
ECU code light comes on. (for the first few days it never came on but gradually came on more)

At first I thought it was a fuelling problem so replaced fuel filter first then the fuel injector second. Both seemed to work but then the problems returned. So i decided to stump up and pay a garage to read the error code. It said Throttle Potentiometer.

The throttle potentiometer detects the throttle angle and from that the ECU decides the right fuel map to run, so if this where faulty you could see every one of those symptoms through the wrong fuel map suddenly being chosen.

The throttle potentiometer is a non-serviceable part, calibrated in the factory. You should never remove it as the Fiat manual states. If it fails you have to buy a new throttle body.



I was tempted to strip it down clean it and have a look inside. By this point I was getting annoyed and just wanted my car reliable, so I did not try it

I had a cunning plan though, as cunning as a fox who's just been appointed Professor of Cunning at Oxford University. Use spray paint to mark where the throttle potentiometer was. This way I could refit it in the factory position.


Bit of masking tape newspaper and old exhaust paint.



Screws out and you can see just how much movement the throttle potentiometer has.


Obviously connected to this is the butterfly valve and on the other end the throttle cable. You can see the spray paint has marked the throttle potentiometer position on the body. Nothing visibly wrong in here, I was expecting oil contamination to be honest after my other problems.


Back of the throttle potentiometer. Nothing obviously wrong to me. You can see where the contacts have worn the tracks. Notice its much heavier ware on the minimum throttle side compared to the maximum throttle side. I presume a new one would not have those marks at all.

<- Min Throttle ---|--- Max Throttle->


I was going to do a test on the throttle potentiometer by powering it with a computer PSU and using a multimeter to test the output when moving the throttle. My problem was so frustratingly intermitent I doubted anything would have been proven and just wanted my car fixed as soon as possible so didnt bother.

Tomorrow If I have time I will try the test.


In summary a very pointless thread with some nice pictures
It might be worth cleaning the contacts if you feel like having a play But! I can not guarantee that spray paint will be accurate enough to refit the throttle potentiometer perfectly.
Thanks NetEnforcer, Dan89 thanked for this post

Last edited by Adrian Bravo; 08-10-2009 at 09:58. Reason: Some engrish
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Old 11-06-2010   #2
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Re: Looking inside the 1.4 12v Throttle Potentiometer / Position Sensor

Just for searchability, this throttle potentiometer is sometimes called a throttle switch or throttle position sensor TPS .
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Old 12-06-2010   #3
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Re: Looking inside the 1.4 12v Throttle Potentiometer / Position Sensor

Are you thinking of the idle stepper motor? That also contains a switch that detects when the throttle is not pressed
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Old 14-06-2010   #4
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Re: Looking inside the 1.4 12v Throttle Potentiometer / Position Sensor

Not sure. They said my faulty part was the "throttle switch". I could see a replaced part (different colour to original one). I'll check tomorrow then definitely know what it was! I see what you mean though, maybe they replaced the idle stepper motor throttle switch, not the potentiometer throttle switch.

This thread is sure going to jump up the "throttle switch" search results list now!
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Old 27-10-2011   #5
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Re: Looking inside the 1.4 12v Throttle Potentiometer / Position Sensor

Hi guys, i have fiat brava 1.4 12v, that spray lug light appears on dashboard sometimes, and the same thing when i start car seems like going to shut down but this happens like once a week. some people says here you should clear ERG or throttle body, i dont know where they locate in that engine at all, please is anyne can help me and with picture will be more detialed
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Old 31-07-2017   #6
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Smile Re: Looking inside the 1.4 12v Throttle Potentiometer / Position Sensor

Hi,

Where can I buy only a throttle Valve Spindle? Is there any source in Ebay?
And do you know any shop sell Mono Point Injector?

I found Potentiometer in sand and black color? Are they different?


Thank you
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