MY 87 350 IROC will not idle and acts like it has 7 cylinders. It has new injectors, cap rotor,plugs,wires. I have swapped the ESC, MAF burn, MAF power. TPS is .54. The scanner says CTS is 245* so I put ih a new one. Still 245* W T F !!! Is it the ECM? what do I check next? All else is good with the scanner, no codes and everything seems to be working fine.

 

Also from what I understand the yellow wire at the CTS is supposed to have 5 volts with the CTS connected. Mine is about half that. I checked the voltage at the ECM for 5volts where the wire supplys the TPS, it has 5 volts. So is the ECM putting out 5volts to the TPS and not to the CTS? Is the CTS only seeing half of the signal it needs to show resistence on? Is this why the temp is roughly twice what it should be?

 

Is it reading 245* when the car is cold?

Let your car cool down, out of the sun. Pull the CTS connector wire. Then measure the resistance across the CTS sensor probe leads directly withe a multimeter. Its easier if its out of the car.

Then compare the resistance it has with the CTS temp/resistance chart. There is one in this thread:

https://www.thirdgen.org/techbb2/sho...ight=CTS+chart

If its in the right ballpark then its probably OK and I'd look elsewhere.

If both CTS sensors say 245 then either they are the wrong ones or you have a problem somewhere else. Are you sure the scanner is working right?

I don't have the CTS circuit in front of me, so I'm not sure on the CTS voltage measurement your asking about.