General Really Driving me Mad

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General Really Driving me Mad

blue80sx

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Aug 19, 2007
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Bloody car, I thought I cracked it today by putting on a throttle body, nice steady idle at 900rpm, go to drive it this afternoon and the idle is all over the place again 1500 to 2500 and back every 2 seconds.

So far I have done the following

replaced the ECU
replaced the cambelt
replaced the plugs
replaced the leads
replaced the stepper motor
replaced the throttle body
replaced the coil
replaced the temp sensor
replaced the pressure sensor
had the wiring checked
had the injectors cleaned
put on a diagnostic twice

and still the idle speed goes up and down. I cannot seem to fix it despite being able to fix every car I have ever owned, garages cannot seem to
find a fault or tell me what is wrong with it.

Any one have any idea what I need to do to this steaming pile of crap before I do a Jeremy Clarkson and just shoot the damn thing with a 12 bore.

BTW why does a Fiat forum have an ad for a Renault running over it?




 
Have you had Lamda (oxygen) sensor checked? Don't know if it would give these symptoms or not.
 
forgot, I have changed the lambda, done so much and with a genuine Fiat part, not a universal jobbie

the ECU is an exchange so should not be that

air leaks, sprayed easy start over the inlet side of things and no increase in engine speed

timing is spot on, done properly, locked the cam etc etc

ECU reset, done loads, thrashing it to clear it. lots of that.

seems to be something to do with the stepper motor, too regular to be eg an air leak consitant from 1500 to 2500 and back to 1500 every 2 seconds and so it goes on. If I physically remove the stepper motor, but leave it connected electrically the idle is fine, rock solid which negates suggestion of any air leak, head gasket etc.

Something to do with all the Bosch crap on it telling the engine what to do. Damn those Germans
 
have you had diagnostics done mine same couldnt find fault dont know what to do next
 
yep, had two done, shows no fault one at a specialist the other at a dealer

no engine management light on BTW
 
if its a 1.2 then this is a common problem if a fiat exmainer is not used to perform what fiat call the "motorized throttle valve angular position learning procedure". the manual method to do this is switching ignition on (but engine off) for 45secs then turning it off, however this often doesnt seem to work on the 1.2. try disconnecting battery for an hour, then try the manual method. if that doesnt work then a fiat examiner is needed to force it to relearn the throttle position.

however, dont waste your time and money trying this until you have checked very carefully for vacuum leaks, and by check i mean remove each breather and vacuum hose and check every mm of it for cracks.
 
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it has a stay of execution :p

the damn thing is now working fine, and I have done nothing, played up on me Sunday evening having being working OK Sun afternoon, daughter said it was not too bad on Monday, so I have driven it myself today for 30 miles and it behaved itself all the time, in traffic on the motorway etc etc

There is always the nagging doubt it may return as suddenly as it stopped, but for the time being its fixed, I am convinced its electrical somewhere, but I will save cleaning up the earths etc until it goes again.

Thanks being for the shoulder to cry on, this one almost had me beat.

Now Dad can return to his true mission in life, restoring his V6 Alfa 75. :D

vacuum hoses all ok BTW
 
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