Having some fluctuating idle issues with my '96 Barchetta - I've replaced the ICV ( stepper motor ) the solenoid on the side of the throttle control plate, changed injectors, changed coils, checked for vacuum leaks all in an effort to fix the issue.

Car starts and runs fine when cold as soon as I drive idle increases to about 2,000 rpm and then fluctuated down to about 1,000 then up again surging. whine's doing this if I unplug and replug the ICV electrical connector the idle smooths out and it will run fine until I turn off car and restart - when I unplug the connector I get the injector dash warning light... but the car runs just fine.

My question is what sensor or circuit controls the ICV - I'm assuming it does;t operate all the time it's only when the car is warm or cold that the little steer motor is running...

I have replaced the Lamda sensor ( about 2000 km ago ) - also changed out the fuel pump and fuel filter

The car only has 49,000 KM so things shouldn't be worn out... it's getting frustrating. I heard of people hooking up computer to the car to read operation the ODB1 really doesn't give you ton of information unless I'm not supposed to be hooking up under the dash and maybe somewhere int he engine compartment -

Any suggestions or help would be appreciated...

DM914 said:

<SNIP>

My question is what sensor or circuit controls the ICV - I'm assuming it does;t operate all the time it's only when the car is warm or cold that the little steer motor is running...

I have replaced the Lamda sensor ( about 2000 km ago ) - also changed out the fuel pump and fuel filter

The car only has 49,000 KM so things shouldn't be worn out... it's getting frustrating. I heard of people hooking up computer to the car to read operation the ODB1 really doesn't give you ton of information unless I'm not supposed to be hooking up under the dash and maybe somewhere int he engine compartment -

Any suggestions or help would be appreciated...

Click to expand...

The main signals determining an ICV setting would be engine speed, and coolant temperature. I't suspect a faulty temperature sensor. Note that this may be a separate sensor from the one that drives the temperature gauge.

Robert G8RPI

thanks for the info - now to find out where the temp sensor is and what is a part number. I had bought a NEW ICV ( Stepper motor off Ebay ) and like a few others I think that it's a substandard part compared to the original ( expensive ) part. After mucking with all of these other fixes - I put my old ICV back on after cleaning it up and the car runs perfect.... So the $ 35.00 non oem part probably cost several hundred in replacement parts trying to fix something that was related to a poor replacement part ! live and learn