http://www.brickboard.com/FAQ/700-90...nsor_Diagnosis

With everything connected and running, the O2 sensor voltage (green wire)will swing from .1 to .9 VDC very quickly.

 

OK then the range on my meter must be wacky I will look at it.

Then I correct myself from above statement between 0 and 1.0 volt.

 

Okay guys! Thanks for the replies! I didn't think 1-12v sounded right, I was getting confused. I am getting correct sweeping voltage, so I guess the lack of continuity at 24 on the ECU isn't cause for alarm.

I have a rebuilt IAC valve on the way to correct my IAC valve problems.

In other news, a new Air Mass Meter / Mass Air Flow Sensor seems to have made my car better. No fueling codes set like before, and overall response is improved.

The old AMM / MAF checked out fine though. Kinda strange that a failing AMM would cause crazy weird stuff to happen and not fail any checks, but I guess that happens sometimes? Beats me....

 

LOL yup I had a feeling that would play in here.

 

I had the same problem on my 2000 S-40 1.9 turbo
found the problem on Idle control valve connector pins
Pins was all green due to water penetration
Cleaned pins and harness with carburetor cleaner
And cleaned valve too
Reinstalled valve back with same older gasket with silicone
Car RUNS FINE NOW
found this tip on You tube

 

Dear Sir, PIERCE who is a member of this Forum mentioned to me that my volvo 240 1990 will NOT have a fast idle at start. That once you turn it on, that's it. My idle used to be smooth but now it's rough and when you start the car the tach needle jumps up and down from 950 to 1000 and then when you put your foot on the gas to 2500 till its hot and release it is 850 even and pretty smooth. what do you suggest?