Very rich hmmmmmmmm, better check for vacumn leaks and 02 problems.

 

The .56Vdc value is ONLY valid for base idle of 450rpm; .78Vdc at normal idle of 600-700rpm is quite normal.

 

Had a friend chasing an intermittent for almost a year before he found it to be the CTS, seemed the computer would correct for it before it through a code.

 

Rick...is there a way to check the CTS??

 

I'm not quite sure, but the FSM says "There should be 5 volts present at the sensor connector, if measured with a Digital voltage ohm meter". To me there's a problem though because it's (The CTS) is a thermistor, as the engine warms up the sensor resistance becomes less, and the voltage drops. The CTS has caused havoc with alot of members, if it's scewed it can cause either a rich condition, or possibly a lean. But like I said, my friend chased an intermittent for one year, and he's alot smarter than I am. There are trouble shooting trees in the FSM, only problem there is catching something that only happens intermittently, or something the computer can correct for before a code is thrown.

Wish I could be more help with that. But your symptoms lead me to post about it, especially the rich condition. Mick could probably explain this better, but you don't have a cold start injector, that ended in 89. So, the CTS sends it's signal to the ECM, which compensates the AFR, low temps, it adds more fuel, if it's intermittent or bad, (voltage not dropping properly) you'll have a rich condition. Like any intermittent their hard to catch.

 

Thanks for the reply Rick...when my vette comes out in the spring and the problem that I have becomes more of a problem; I will replace the CTS . At least I have more options now than I had before.
Thanks again to all that replied!!!!

 

I think the same, is a possibility. I don't know about being able to explain it any better, and also agree w/possible intermittent failures and codes. Additionally I think the OP needs to change the injector constant to match the size of the injector instead of rigging the FP that low to comp. the BLM....MO
My thoughts were because the 727/730 ecm's prportional fuel control uses 2 tables for basic fueling in Open Loop (aside from pulse width, battery voltage etc.). Both of these are based on 'look up' from coolant temp., to deliver an added amount of fuel for various temps. Colder temps -40c will have the most amount of fuel added to net approx. 10.1 afr as it heads toward 90c it begins to taper down (less fuel added). If the CTS were funked up, and let's say continued (regardless of real motor temp) to give a lower reading to the ecm, than real operating temp., it could be giving a motor that is operating @120* the same fueling that was being added at say 40c. (we are only talking about Open Loop, colder or cold weather start/running). Compounded with interminttent failure, the car would still be going into closed loop, and not just stuck in open loop, and yet doing funky things on warm up. This is what Rick is referring to.
I don't have my FSM here in front of me now, but I know they have it measured and tested w/ohm readings. I don't usually use a vohm anymore, every time my car is running I have the laptop on, w/a scan program tts or the like, and just watch the operation of all sensors. When they are looking sluggish to that point etc.I usually swap them out. I have watched bad 02's this way that wouldn't barely move let alone go over the cross over, and throw the tune rich, etc. etc........and never throw a code, maybe I didn't wait long enough....yeah it's possible.
As I mentioned earlier, I would be looking all of it over.....
did I mention change the injector constant for that to 24# so you can put the fuel pressure back to were it should be ?...don't remember.