Simple question:

Can the CTS be bad and cause issues yet read what seems to be a correct temp on the scanner? Is it normal for the CTS while fully warmed up to read about 185-195 yet the engine temp gauge read 220-230? I know they are 2 different sensors and the engine temp gauge is by the headers but is 40 or so degrees too much of a difference?

 

If one of the issues you are talking about is hard starts...Yes. It happened to me but it wasn't the sensor itself. It was the ECM. Everything was reading about 25* too cold. Check the voltage at the plug. It should get 5 volts.

 

my problem is cold start erratic idle, surges, stalls if i snap the throttle ect. then its a hard start after the stall

 

Discription of a bad Oxygen sensor.

 

yeah but im talking cold start in open loop so isnt the o2 sensor out of the picture? when the car warms up and goes into closed loop it runs great

 

Any codes?

If as you state the engine runs fine when in closed loop and the O2 is working then that would also indicate
the CTS ( at least when warm ) is working correctly.
Maybe it is reading wrong when cold?
Meter the CTS terminals when cold to see if the ohm figure relates to what they should be
http://www.chevythunder.com/cts_diagnostics.htm
http://www.chevythunder.com/cts_diagnostic_pg2.htm

 

My past experience ( assuming a correctly functioning CTS ) is that the gauge reading is usually the more inaccurate of the two , esp with age.
Only way to confirm true temp at the sender location is with a heat gun or a mech temp gauge connected temporarily

 

No codes temp matches mat when cold on scanner.

 

hmm maybe its something with the IAC, however it was a brand new OEM...

 

How about compared to ambient temperature when cold? If it's reading warmer then ambient that could make for hard starts.

 

ambient temp this morning was about 55

 

How does that compare to the temperature on the scanner?

 

spot on

 

Doesn't sound like your problem is your CTS then does it...I would go thru the adjustment of the tps and iac again and see what happens. It might just need to be cleaned out. They can build up a lot of carbon.

 

That was my opinion also. So as a last resort, I changed the O2 sensor ($20.00 Part) and my problems were solved. At first start up good idle, no stalling, no hesitation and runs great Cold & Hot. I should have changed that part years ago but kept looking elsewhere to no avail.

 

wow, makes no sense but thats what im gonna do next....


would your car work good in closed loop when warmed up as well before you changed the o2?

 

When it warmed up it was allright in a sense. I was running rich, gas mileage went south and it did stall with the A/C on when in reverse. Otherwise it was good but not great. Like you I chased a lot of things before I said what to H--- and changed the O2 sensor which was 10 years old.

 

im gonna give it a shot

 

the o2 sensor was new last april, when the car was put together, but shortly after i had a injector get stuck open and melted the cat..... big mess... needless to say maybe the o2 got fouled