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Discussion Starter · #1 ·
It's been a week since I took my Z out from winter storage.
Juts for background information I had my PCM reconfigured two years ago by Breathless to turn fans on, delete 1 to 4 shift and tune the car with current mods.

Since driving it on the road I've notice my 1 to 4 shift light comes on both my oil and coolant temps are running at 220-225 F just for city driving at an air temp of 76 F?

No codes, fans are on and I can't figure out what's going on.
Comments please...
 

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Even with the CAGS eliminated, via computer tune or otherwise I believe the Shift light will still come on bu the solenoid will not prevent you from getting into second. I know thats the case with the CAGS eliminator but the computer programming might be different. I am sure someone will chime up.
As far as the coolant temps, I am a big fan of checking the cheapest part first and working up from there. I'd check the thermostat, probably replace it, since you said your fans were on but the coolant temp was remaining higher than normal.
Of course you said City driving so if your hitting a lot of stop and go those temps are not too drastic. I was in LA a couple days ago and hit rush hour traffic leaving, my temps increased to about the same you mentioned, I think 226 was as high as the coolant temp got before the thermostat opened. I do not have a comuter tune on my car so to get my fans on sooner I turn the AC on and the fans come on with it.
 

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I had the skip shift eleminated by computer tuning at MMS (before they went south) a few years ago. The shift light does not come on.

Zrod
 

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I can only relate my experience with my car. I have a computer tune and my fans are set to go on at 193F and off at 183F. I live in hot, humid Texas. My coolant never goes above 190F. I run at about 187F most the time. My oil runs at 199F to 220F. If your tune is working, you should be able to hear the second (large) fan when it comes on. If their coming on at the programed temps. check your thermo as stated before and check the cavity in front of the spoiler for blockage.

Chas.
 

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Discussion Starter · #5 ·
The thermostat was the first thing I thought of but I installed a 160 F thermostat two years ago so it can't be shot now can it? Even if the thermostat is shot why are the oil temps so high?
 

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1) PCM reprogramming to disable skip shift can be done in a couple of different ways. Depending on which of the programming variables were changed, the light can still come on. On mine, I used LS1Edit to set the "enable temperature" to 255 and the %TPS-to-disable at 1. No light, ever.

2) Check up under the Radiator shroud. Corvettes are notorious for sucking all sorts of crap up into the front of the radiator. I blow mine out at the Shop every few months and tons of debris always comes out. There's an aftermarket screen you can buy to cover over the shroud opening at the bottom that will reduce how much stuff gets up into the radiator

3) Thermostats do fail. If you know how to do it, you can pretty much tell when a thermostat opens by holding/squeezing the radiator coolant return line. But I wouldn't know how to describe it well enough to tell you if you don't already know. If you suspect the thermostat, remove it and put it in a pot of water on the stove. Turn on the Burner. Use a candy thermometer of any similar suitable instrument and watch to see what the water temperature is when the thermostat opens.

230º Temps in traffic isn't a particularly unusual complaint. The C5's radiator is marginal at best, it only takes a small change in operating conditions to make a large difference in operating temperature. My car will run all day at 192-198º, which is about what the factory T-Stat is set for, but if I turn on the A/C it'll go up by 20-30º even on the highway with plenty of airflow.

Are you sure the A/C wasn't running? Remember that turning on the defroster automatically turns on the A/C, and that when the climate control is in "Auto" it'll turn the A/C on whenever it wants, which could easily be when you think it's cool enough that it isn't necessary.
 
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