Technical 75SX Reving like Herby gone bananas!

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Technical 75SX Reving like Herby gone bananas!

marzocchi

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Jan 26, 2006
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Hi can any body help? I've got a Punto 75 SX that every now and then (mainly on a cold morning) will begin to rev on it own accord. For example on aproaching a set of lights at slow speed it will speed up reving up to 3000-4000 revs, once I hold the clutch down it will then rev up and down like it's about to start a race!!! It's embarrassing! What is causing it and how do I fix it? Any help would be great. So far all that seems to cure it as a quick fix is giving it a thrashing down the motor way on the way to work!!!
 

bennett

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Mar 13, 2006
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Crewe
Im having same trouble with mine, and i still don't know why it does it
 

pid119

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Jan 17, 2006
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OLDHAM
i had this on my old 1.6 sporting it turned out to be the lambda sensor
 

bennett

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Mar 13, 2006
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Crewe
Where is the lambda sensor in the engine, and how easy would it be to replace yourself?

How much mulah are we talkin aswell?
 

mattiewoo

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Mar 30, 2006
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hi, does the injector light come on on the dash? if not then i doubt its your lambda sensor, which is located in the exhaust down pipe, (looks like a 22mm bolt with wires coming out of it) your problem sounds like a faulty ar dirty throttle position sensor or AIT(air intake temperature) sensor which is located on the throttle body on the side of the butterfly get some carb cleaner and give it a squirt in 3 second bursts while revving the engine to about 4000rpm, hope this helps.
 

bennett

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Mar 13, 2006
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Crewe
Do you mean when i turn the ignition or when i get the problem? the ignition light it comes on when you start the car i havent noticed if it does it when i get the problem of the revs
 
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Aug 2, 2005
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You're all wrong lol. Only kidding but i have just solved this problem on my 75. There is a temperature sensor you will need to replace on the opposite end of the engine to the timing belt. Its called the Coolant remperature sensor and has two wires coming out of it unlike the temperature sensor for the clock inside the car which has one and is situated beside the timing belt on the back of the engine also. This temperature sensor talks only to the ECU to let it know when the engine is hot to fuel extra so that the fuel does not evaporate etc... It looks like this and the end of mine (i think) was damaged when my engine over-heated due to my fan not working without my knowledge lol
DSC00917.JPG


Hope this helps, below is the thread where i posted about mine :)

https://www.fiatforum.com/showthread.php?t=57269

Jordan
 
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marzocchi

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Jan 26, 2006
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Cheers for the help I'll give that a go once this bloody weather changes! Also my injecter light comes on when I start the car and it goes on and off whilst driving! Is this related?

Thanks for your help :slayer:
 
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Well that depends. When you start teh car your injector light should come on and stay on for about 3 seconds, whilst it pressurises and fills each one, tehn go off, tehn you should start teh car. It wont do much if any damage not waiting apart from it might take a couple more turns to start. My injector light was coming on and off becuase my fuel wasnt getting to the injectors as they were sensing a pressure drop but my temperature sensor was saying there wasnt anythign wrong as it was still giving a miniaml reading, so it probably is related. Mine would come on and off whilst driving - does yours do it whilst you are drivign too?

Jordan
 
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marzocchi

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Jan 26, 2006
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Yeah mine does it when driving. It goes off before I start the car, it will then come on for about 3 minutes than go off after steady town driving but it will then re-appear once on the motorway and reving higher!

I changed the Lambda sensor on mine the other day hoping this would cure it. The car was instantly tighter! zippier and better on fuel. However the random reving up and down between 3000-4000 revs when sat in traffic has come back with vengence! and the injector light still comes on and off when driving!!!

Any ideas would be great.
 
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