F355 clicking noise/abrupt minor rpm change at idle

I have a 97 355 spider that changes rpm's slightly, but abruptly, while idling. There is a definite "clicking" noise that accompanies the sudden rpm change, and it almost sounds like engine shuts off at same time, for just a split second.

Any thoughts on what this is? Serious coin to fix?

 

Are you sure it's not the AC compressor turning on ?
Have you tried to stop the fan and press the stop button ?

 

SHARK is correct... It could be 2 things.... related to the rad fans..

Noticable at idle. 1) Either the water temp gets to 190 which causes the fans to kick on OR 2) the a/c compressor kicks on which also causes the fans to kick on.

The fans draw a heavy elec load. The car will momentarily "dip" down in idle, then within a 1/2 second increase idle to compensate.

This is normal. The click is either the fans switch or the a/c compressor.

If the dip in RPM is severe, I mean really low RPM where she almost wants to die, remove the fan switch (on top of the fans) clean the connector, plug back in - good to go. But first try putting some miles on the car. Seems if cars have been sitting for a long time or garage queens will do this more on initial drive until car really warms up and gets miles on it.

 

It's not a/c unit kicking on as it happens whether stop button is depressed or not, and it starts happening immediately upon starting, before car is warmed up. Also, it's definitely more radical than the noise you get when a/c compressor goes on, and it keeps happening, at intervals of about every 15 seconds.

Since rpm dips have come down pretty low at times, I'll try cleaning fan connections. This may work esp. it does seem to get better after it's been driven for awhile.

 

Change your spark plug wires, u can buy the #7 wire first, save the cost of the whole set. It seems #7 has had alot of problems.

 

Sorry for late reply, but thanks for info on plug wire. I'll try that too.